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[原创] Qiling框架分析实战:从 QilingLab 详解到 Qiling 源码分析
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2023-5-29 21:42 20474
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前言
最近在学习 IoT 相关漏洞利用,打算先学习一下 Qiling 框架,为后续的漏洞利用文章做铺垫。 Qiling 框架是基于 unicorn 的多架构平台模拟执行框架,提供的仿真环境很全面,能够在模拟执行的基础上提供统一的分析 API,这个A PI 包括插桩分析、快照、系统调用和API劫持等操作。在2021年JOANSIVION提供了两个QilingLab能够针对Qiling框架各种操作进行学习的程序,并提供了相应的writeup。他提供的 writeup 是 arm 架构的,因此本文以 x86_64 架构为基础,在他的文章上进行相应补充。程序下载地址放在了文末参考链接中。
时隔两年,Qiling 框架进行了很多更新与改动,我在完成 QilingLab 的过程中发现高版本的 Qiling 存在问题,因此从代码审计的角度入手,分析并提出解决方案,如果曾经分析过 QilingLab 的朋友可以直接跳到 Challenge 10 部分。本文将以最为基础的视角来陪着大家从 0 到 1 学习 Qiling 框架,希望大家看完能有所收获。
首先下载Qiling:
1 | git clone - - recurse - submodules https: / / github.com / qilingframework / qiling.git # 使用 --recurse-submodules 递归下载模块,rootfs是单独更新的项目 |
使用版本为最新版:
1 2 3 4 | > pip show qiling Name: qiling Version: 1.4 . 5 Summary: Qiling is an advanced binary emulation framework that cross - platform - architecture |
可以看到 QilingLab 提供的11个挑战如下:
1 2 3 4 5 6 7 8 9 10 11 12 13 | Welcome to QilingLab. Here is the list of challenges: Challenge 1 : Store 1337 at pointer 0x1337 . Challenge 2 : Make the 'uname' syscall return the correct values. Challenge 3 : Make '/dev/urandom' and 'getrandom' "collide" . Challenge 4 : Enter inside the "forbidden" loop. Challenge 5 : Guess every call to rand(). Challenge 6 : Avoid the infinite loop. Challenge 7 : Don 't waste time waiting for ' sleep'. Challenge 8 : Unpack the struct and write at the target address. Challenge 9 : Fix some string operation to make the iMpOsSiBlE come true. Challenge 10 : Fake the 'cmdline' line file to return the right content. Challenge 11 : Bypass CPUID / MIDR_EL1 checks. |
整体分析
运行一下程序,可以看到输出了挑战的所有题目:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 | > . / qilinglab - x86_64 Welcome to QilingLab. Here is the list of challenges: Challenge 1 : Store 1337 at pointer 0x1337 . Challenge 2 : Make the 'uname' syscall return the correct values. Challenge 3 : Make '/dev/urandom' and 'getrandom' "collide" . Challenge 4 : Enter inside the "forbidden" loop. Challenge 5 : Guess every call to rand(). Challenge 6 : Avoid the infinite loop. Challenge 7 : Don 't waste time waiting for ' sleep'. Challenge 8 : Unpack the struct and write at the target address. Challenge 9 : Fix some string operation to make the iMpOsSiBlE come true. Challenge 10 : Fake the 'cmdline' line file to return the right content. Challenge 11 : Bypass CPUID / MIDR_EL1 checks. Checking which challenge are solved... Note: Some challenges will results in segfaults and infinite loops if they aren't solved. [ 1 ] 8036 segmentation fault (core dumped) . / qilinglab - x86_64 |
先调用Qiling仿真环境运行一下:
1 2 3 4 5 6 7 | from qiling import * if __name__ = = '__main__' : path = [ "qilinglab-x86_64" ] rootfs = "rootfs/x8664_linux" ql = Qiling(path, rootfs) ql.run() |
发现报错:
1 | unicorn.unicorn.UcError: Invalid memory read (UC_ERR_READ_UNMAPPED) |
接下来进行分析无法运行的原因,按照出题人所说需要解决第一个挑战才能正常进入。首先查看一下文件信息,可以看到程序使用小端顺序,符号表未裁剪:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 | > readelf - h qilinglab - x86_64 ELF Header: Magic: 7f 45 4c 46 02 01 01 00 00 00 00 00 00 00 00 00 Class: ELF64 Data: 2 's complement, little endian Version: 1 (current) OS / ABI: UNIX - System V ABI Version: 0 Type : DYN (Shared object file ) Machine: Advanced Micro Devices X86 - 64 Version: 0x1 Entry point address: 0xa80 Start of program headers: 64 (bytes into file ) Start of section headers: 15840 (bytes into file ) Flags: 0x0 Size of this header: 64 (bytes) Size of program headers: 56 (bytes) Number of program headers: 9 Size of section headers: 64 (bytes) Number of section headers: 29 Section header string table index: 28 |
1 2 | > file - L qilinglab - x86_64 qilinglab - x86_64: ELF 64 - bit LSB shared object , x86 - 64 , version 1 (SYSV), dynamically linked, interpreter / lib64 / ld - linux - x86 - 64.so . 2 , for GNU / Linux 3.2 . 0 , BuildID[sha1] = 76164e6b494c1af9d9f746e2dc7d3663cc23525c , not stripped |
拖到IDA里看一下函数流程,main函数:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 | ; Attributes: bp - based frame ; int __cdecl main( int argc, const char * * argv, const char * * envp) public main main proc near var_10 = qword ptr - 10h var_4 = dword ptr - 4 ; __unwind { push rbp mov rbp, rsp sub rsp, 10h mov [rbp + var_4], edi mov [rbp + var_10], rsi mov eax, 0 call start mov eax, 0 leave retn ; } / / starts at 15CA main endp |
可以看到跳转到start,查看一下start伪代码:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 | unsigned __int64 start() { int v0; / / eax int i; / / [rsp + 0h ] [rbp - 20h ] int v3; / / [rsp + 4h ] [rbp - 1Ch ] int v4; / / [rsp + 4h ] [rbp - 1Ch ] int v5; / / [rsp + 4h ] [rbp - 1Ch ] int v6; / / [rsp + 4h ] [rbp - 1Ch ] int v7; / / [rsp + 4h ] [rbp - 1Ch ] int v8; / / [rsp + 4h ] [rbp - 1Ch ] int v9; / / [rsp + 4h ] [rbp - 1Ch ] int v10; / / [rsp + 4h ] [rbp - 1Ch ] int v11; / / [rsp + 4h ] [rbp - 1Ch ] int v12; / / [rsp + 4h ] [rbp - 1Ch ] char v13[ 11 ]; / / [rsp + Dh] [rbp - 13h ] BYREF char v14[ 11 ]; / / [rsp + Eh] [rbp - 12h ] BYREF char v15[ 11 ]; / / [rsp + 10h ] [rbp - 10h ] BYREF unsigned __int64 v16; / / [rsp + 18h ] [rbp - 8h ] v16 = __readfsqword( 0x28u ); / / __readfsqword指令的参数是一个偏移量, 0x28u 是一个无符号整数常量,值为 0x28 ,即 40 ,表示从FS寄存器中的偏移量为 40 的地址开始读取 64 位数据。 for ( i = 0 ; i < 11 ; + + i ) v13[i] = 0 ; printf( "Welcome to QilingLab.\nHere is the list of challenges:" ); printf( "\nChallenge 1: Store 1337 at pointer 0x1337." ); printf( "\nChallenge 2: Make the 'uname' syscall return the correct values." ); printf( "\nChallenge 3: Make '/dev/urandom' and 'getrandom' \"collide\"." ); printf( "\nChallenge 4: Enter inside the \"forbidden\" loop." ); printf( "\nChallenge 5: Guess every call to rand()." ); printf( "\nChallenge 6: Avoid the infinite loop." ); printf( "\nChallenge 7: Don't waste time waiting for 'sleep'." ); printf( "\nChallenge 8: Unpack the struct and write at the target address." ); printf( "\nChallenge 9: Fix some string operation to make the iMpOsSiBlE come true." ); printf( "\nChallenge 10: Fake the 'cmdline' line file to return the right content." ); printf( "\nChallenge 11: Bypass CPUID/MIDR_EL1 checks." ); puts( "\n" "\n" "Checking which challenge are solved...\n" "Note: Some challenges will results in segfaults and infinite loops if they aren't solved." ); challenge1(v13); v3 = checker(v13, 0LL ); challenge2(v14); v4 = checker(v13, 1LL ) + v3; challenge3(&v14[ 1 ]); v5 = checker(v13, 2LL ) + v4; challenge4(v15); v6 = checker(v13, 3LL ) + v5; challenge5(&v15[ 1 ]); v7 = checker(v13, 4LL ) + v6; challenge6(&v15[ 2 ]); v8 = checker(v13, 5LL ) + v7; challenge7(&v15[ 3 ]); v9 = checker(v13, 6LL ) + v8; challenge8(&v15[ 4 ]); v10 = checker(v13, 7LL ) + v9; challenge9(&v15[ 5 ]); v11 = checker(v13, 8LL ) + v10; challenge10(&v15[ 6 ]); v12 = checker(v13, 9LL ) + v11; challenge11(&v15[ 7 ]); v0 = checker(v13, 10LL ); printf( "\nYou solved %d/%d of the challenges\n" , (unsigned int )(v0 + v12), 11LL ); return __readfsqword( 0x28u ) ^ v16; } |
查看调用的checker函数伪代码,可以知道当检查到问题已解决时返回1:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 | __int64 __fastcall checker(__int64 a1, int a2) { __int64 result; / / rax if ( * (_BYTE * )(a2 + a1) ) ; 检查数组a1中下标为a2的元素是否为 0 ,非 0 返回 1 { printf( "\nChallenge %d: SOLVED" , (unsigned int )(a2 + 1 )); result = 1LL ; } else { printf( "\nChallenge %d: NOT SOLVED" , (unsigned int )(a2 + 1 )); result = 0LL ; } return result; } |
我们梳理一下函数逻辑:循环初始化数组v13所有元素为0,如果完成对应挑战就会改变v13对应数组的值,再用checker进行一次检查v13数组元素是否为0.再将checker返回值传递给变量,再加到下一次的检查结果上。这个过程不断重复,最后将累加起来的值输出到"\nYou solved %d/%d of the challenges\n"
。
challenge 1: 内存数据修改
拖到IDA里看一下 challenge 1 汇编代码:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 | .text: 0000000000000B8A public challenge1 .text: 0000000000000B8A challenge1 proc near ; CODE XREF: start + 123 ↓p .text: 0000000000000B8A .text: 0000000000000B8A var_18 = qword ptr - 18h ; 分配quadword类型的局部变量var_18位于[rbp - 18h ]的位置 .text: 0000000000000B8A var_C = dword ptr - 0Ch ; qword 8 字节,dword 4 字节 .text: 0000000000000B8A var_8 = qword ptr - 8 .text: 0000000000000B8A .text: 0000000000000B8A ; __unwind { .text: 0000000000000B8A push rbp .text: 0000000000000B8B mov rbp, rsp .text: 0000000000000B8E mov [rbp + var_18], rdi ; [rbp - 18h ], rdi 此处rdi值为指向v13的指针 .text: 0000000000000B92 mov [rbp + var_8], 1337h .text: 0000000000000B9A mov rax, [rbp + var_8] .text: 0000000000000B9E mov eax, [rax] ; 将内存地址 1337h 的值传递给eax .text: 0000000000000BA0 mov [rbp + var_C], eax .text: 0000000000000BA3 cmp [rbp + var_C], 539h ; cmp jnz: 不相等就跳转loc_BB3进行retn ( 539h = 1337 ) .text: 0000000000000BAA jnz short loc_BB3 .text: 0000000000000BAC mov rax, [rbp + var_18] .text: 0000000000000BB0 mov byte ptr [rax], 1 ; 将值为 1 的字节写入存储在rax所指向的内存地址中 .text: 0000000000000BB3 .text: 0000000000000BB3 loc_BB3: ; CODE XREF: challenge1 + 20 ↑j .text: 0000000000000BB3 nop .text: 0000000000000BB4 pop rbp .text: 0000000000000BB5 retn .text: 0000000000000BB5 ; } / / starts at B8A |
可以看出我们需要让内存地址1337h处的值为1337才能让cmp判断相等,rdi传入的是数组地址对应数组首个元素地址,相等后调整rdi地址处的值为1,这也符合后续被checker函数检查数组后进行的一系列操作。
1 2 3 4 5 6 | .text: 0000000000000B8E mov [rbp + var_18], rdi ... .text: 0000000000000BAC mov rax, [rbp + var_18] .text: 0000000000000BB0 mov byte ptr [rax], 1 |
challenge 1 对应的伪代码如下:
1 2 3 4 5 6 7 8 9 10 11 12 | _BYTE * __fastcall challenge1(_BYTE * a1) { _BYTE * result; / / rax result = (_BYTE * ) * (unsigned int * )((char * )&loc_1335 + 2 ); / / 标识符loc_xxxx通常用于表示一个内存地址或常量值 if ( * (_DWORD * )((char * )&loc_1335 + 2 ) = = 1337 ) { result = a1; * a1 = 1 ; } return result; } |
在Qiling中编写字节序列常用有以下方式,我选用的是pack16。
1 2 3 4 5 6 | ql.mem.write( 0x1000 , b '\x41\x42\x43' ) # 手动输入 ql.pack( ">I" , 0x12345678 ) # 函数调用将返回一个4字节的大端序字节序列,其中包含整数值 0x12345678 的二进制表示。 # ">I"参数指定了这个字节序列的格式,其中">"表示大端序,"<"表示小端序,"I"表示一个32位无符号整数。 ql.pack16( 0x1234 ) # 这个函数专门用于16位整数 |
writeup 1
根据前面的分析可以得到 challenge 1 writeup:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 | from qiling import * def challenge1(ql): ql.mem. map ( 0x1000 , 0x1000 , info = '[challenge1]' ) # 为地址范围 [0x1000, 0x2000) 映射了一块内存,第一个参数0x1000是映射的起始地址,第二个参数0x1000是映射的大小,映射的大小必须是页大小的倍数,这里的页大小是 Qiling模拟器的默认页大小,4096字节。info是对这部分内存做的一个标记,后续Qiling如果想接着使用的话就可以用这个标记来定位。 ql.mem.write( 0x1337 , ql.pack16( 1337 )) # 将整数值 1337 转换为一个16位字节序列写入内存地址 0x1337 所指定的内存位置,小端输入 if __name__ = = '__main__' : path = [ "qilinglab-x86_64" ] rootfs = "rootfs/x8664_linux" ql = Qiling(path, rootfs) challenge1(ql) ql.run() |
运行上面的脚本,可以看到 challenge 1 已经解决:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 | Challenge 11 : Bypass CPUID / MIDR_EL1 checks. Checking which challenge are solved... [ = ] write(fd = 0x1 , buf = 0x55555575a260 , count = 0x54 ) = 0x54 Note: Some challenges will results in segfaults and infinite loops if they aren't solved. [ = ] write(fd = 0x1 , buf = 0x55555575a260 , count = 0x5a ) = 0x5a [ = ] write(fd = 0x1 , buf = 0x55555575a260 , count = 0x1 ) = 0x1 [ = ] uname(buf = 0x80000000db70 ) = 0x0 Challenge 1 : SOLVED [ = ] write(fd = 0x1 , buf = 0x55555575a260 , count = 0x14 ) = 0x14 [ = ] openat(fd = 0xffffff9c , path = 0x555555555698 , flags = 0x0 , mode = 0x0 ) = - 0x2 (ENOENT) [ = ] read(fd = 0xffffffff , buf = 0x80000000dce0 , length = 0x20 ) = - 0x9 (EBADF) [ = ] read(fd = 0xffffffff , buf = 0x80000000dcdf , length = 0x1 ) = - 0x9 (EBADF) [ = ] close(fd = 0xffffffff ) = - 0x1 (EPERM) [ = ] getrandom(buf = 0x80000000dd00 , buflen = 0x20 , flags = 0x1 ) = 0x20 Challenge 2 : NOT SOLVED [ = ] write(fd = 0x1 , buf = 0x55555575a260 , count = 0x18 ) = 0x18 Challenge 3 : NOT SOLVED [ = ] write(fd = 0x1 , buf = 0x55555575a260 , count = 0x18 ) = 0x18 [ = ] time() = 0x64704df9 Challenge 4 : NOT SOLVED [ = ] write(fd = 0x1 , buf = 0x55555575a260 , count = 0x18 ) = 0x18 |
如果我们想使用Qiling进行远程调试的话,应该怎么做?
我们在使用qemu配合IDA进行远程调试时,需要使用下面的qemu-arm-static:
1 | sudo chroot . / . / qemu - arm - static - g 12345 . / bin / httpd |
查了一下qiling文档,调试qiling的仿真程序需要在脚本中添加下面的代码:
1 | ql.debugger = 'gdb:0.0.0.0:12345' |
接着设置一下IDA的gdb debugger,断点在入口函数处,
运行添加dbg后的脚本:
运行后报错:
1 | ValueError: '/home/ubuntu/Desktop/qilinglab/qilinglab-x86_64' does not start with '/home/ubuntu/Desktop/qilinglab/rootfs/x8664_linux' |
Qiling对于报错的提示都挺好的,这里需要将qilinglab-x86_64放置到指定的rootfs目录(我这里是使用的rootfs/x8664_linux作为rootfs目录)下运行,复制后更改一下程序运行的路径,更改后的代码如下:
1 2 3 4 5 6 7 8 9 10 11 12 13 | from qiling import * def challenge1(ql): ql.mem. map ( 0x1000 , 0x1000 , info = '[challenge1]' ) ql.mem.write( 0x1337 , ql.pack16( 1337 )) if __name__ = = '__main__' : path = [ "rootfs/x8664_linux/qilinglab-x86_64" ] rootfs = "rootfs/x8664_linux" ql = Qiling(path, rootfs) challenge1(ql) ql.debugger = 'gdb:0.0.0.0:12345' ql.run() |
可以看到程序已经可以远程调试了:
challenge 2: hook系统调用
Challenge 2: Make the 'uname' syscall return the correct values.
查看challenges 2 汇编代码:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 | .text: 0000555555554BB6 public challenge2 .text: 0000555555554BB6 challenge2 proc near ; CODE XREF: start + 147 ↓p .text: 0000555555554BB6 .text: 0000555555554BB6 var_1D8 = qword ptr - 1D8h .text: 0000555555554BB6 var_1D0 = dword ptr - 1D0h .text: 0000555555554BB6 var_1CC = dword ptr - 1CCh .text: 0000555555554BB6 var_1C8 = dword ptr - 1C8h .text: 0000555555554BB6 var_1C4 = dword ptr - 1C4h .text: 0000555555554BB6 name = utsname ptr - 1C0h .text: 0000555555554BB6 s = byte ptr - 3Ah .text: 0000555555554BB6 var_32 = word ptr - 32h .text: 0000555555554BB6 var_30 = byte ptr - 30h .text: 0000555555554BB6 var_18 = qword ptr - 18h .text: 0000555555554BB6 .text: 0000555555554BB6 push rbp .text: 0000555555554BB7 mov rbp, rsp .text: 0000555555554BBA push rbx .text: 0000555555554BBB sub rsp, 1D8h .text: 0000555555554BC2 mov [rbp + var_1D8], rdi .text: 0000555555554BC9 mov rax, fs: 28h ; 从Segment fs(用于TLS)对应的内存段,偏移量 40h 处取一个值,把这个值加载到rax寄存器 .text: 0000555555554BD2 mov [rbp + var_18], rax .text: 0000555555554BD6 xor eax, eax ; 清零eax寄存器,更新零标志位ZF = 1 (表示eax为 0 ) .text: 0000555555554BD8 lea rax, [rbp + name] ; 将[rbp + name]的地址传给rax .text: 0000555555554BDF mov rdi, rax ; name .text: 0000555555554BE2 call _uname .text: 0000555555554BE7 test eax, eax ; 不修改eax的内容,只更新标志位 .text: 0000555555554BE9 jz short loc_555555554BFC ; ZF = 1 ,则转移到目的地址 .text: 0000555555554BEB lea rdi, s ; "uname" .text: 0000555555554BF2 call _perror ; _perror() 用于打印错误信息 .text: 0000555555554BF7 jmp loc_555555554D13 .text: 0000555555554BFC ; - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - .text: 0000555555554BFC .text: 0000555555554BFC loc_555555554BFC: ; CODE XREF: challenge2 + 33 ↑j .text: 0000555555554BFC mov rax, cs:qword_55555555567E .text: 0000555555554C03 mov qword ptr [rbp + s], rax .text: 0000555555554C07 movzx eax, cs:word_555555555686 .text: 0000555555554C0E mov [rbp + var_32], ax .text: 0000555555554C12 mov rax, cs:qword_555555555688 .text: 0000555555554C19 mov rdx, cs:qword_555555555690 .text: 0000555555554C20 mov qword ptr [rbp + var_30], rax .text: 0000555555554C24 mov qword ptr [rbp + var_30 + 8 ], rdx .text: 0000555555554C28 mov [rbp + var_1D0], 0 .text: 0000555555554C32 mov [rbp + var_1CC], 0 .text: 0000555555554C3C jmp short loc_555555554C6D .text: 0000555555554C3E ; - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - .text: 0000555555554C3E .text: 0000555555554C3E loc_555555554C3E: ; CODE XREF: challenge2 + CF↓j .text: 0000555555554C3E mov eax, [rbp + var_1C8] .text: 0000555555554C44 cdqe .text: 0000555555554C46 movzx edx, [rbp + rax + name.sysname] .text: 0000555555554C4E mov eax, [rbp + var_1C8] .text: 0000555555554C54 cdqe .text: 0000555555554C56 movzx eax, [rbp + rax + s] .text: 0000555555554C5B cmp dl, al .text: 0000555555554C5D jnz short loc_555555554C66 .text: 0000555555554C5F add [rbp + var_1D0], 1 .text: 0000555555554C66 .text: 0000555555554C66 loc_555555554C66: ; CODE XREF: challenge2 + A7↑j .text: 0000555555554C66 add [rbp + var_1C8], 1 .text: 0000555555554C6D .text: 0000555555554C6D loc_555555554C6D: ; CODE XREF: challenge2 + 86 ↑j .text: 0000555555554C6D mov eax, [rbp + var_1C8] .text: 0000555555554C73 movsxd rbx, eax .text: 0000555555554C76 lea rax, [rbp + s] .text: 0000555555554C7A mov rdi, rax ; s .text: 0000555555554C7D call _strlen .text: 0000555555554C82 cmp rbx, rax ; 相等,则ZF = 1 , CF = 0 , OF = 0 ; 小于,则ZF = 0 , CF = 1 , OF = 0 ; 大于,则ZF = 0 , CF = 0 , OF = 0 .text: 0000555555554C85 jb short loc_555555554C3E ; 前一条指令执行的结果为小于则跳转 .text: 0000555555554C87 jmp short loc_555555554CB8 ; 此处跳出循环 .text: 0000555555554C89 ; - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - .text: 0000555555554C89 .text: 0000555555554C89 loc_555555554C89: ; CODE XREF: challenge2 + 11A ↓j .text: 0000555555554C89 mov eax, [rbp + var_1C4] .text: 0000555555554C8F cdqe .text: 0000555555554C91 movzx edx, [rbp + rax + name.version] .text: 0000555555554C99 mov eax, [rbp + var_1C4] .text: 0000555555554C9F cdqe .text: 0000555555554CA1 movzx eax, [rbp + rax + var_30] .text: 0000555555554CA6 cmp dl, al .text: 0000555555554CA8 jnz short loc_555555554CB1 .text: 0000555555554CAA add [rbp + var_1CC], 1 .text: 0000555555554CB1 .text: 0000555555554CB1 loc_555555554CB1: ; CODE XREF: challenge2 + F2↑j .text: 0000555555554CB1 add [rbp + var_1C4], 1 .text: 0000555555554CB8 .text: 0000555555554CB8 loc_555555554CB8: ; CODE XREF: challenge2 + D1↑j .text: 0000555555554CB8 mov eax, [rbp + var_1C4] .text: 0000555555554CBE movsxd rbx, eax ; 将eax寄存器中的 32 位符号扩展为 64 位,并将结果存储到rbx寄存器中 .text: 0000555555554CC1 lea rax, [rbp + var_30] .text: 0000555555554CC5 mov rdi, rax ; s .text: 0000555555554CC8 call _strlen .text: 0000555555554CCD cmp rbx, rax .text: 0000555555554CD0 jb short loc_555555554C89 .text: 0000555555554CD2 mov ebx, [rbp + var_1D0] .text: 0000555555554CD8 lea rax, [rbp + s] .text: 0000555555554CDC mov rdi, rax ; s .text: 0000555555554CDF call _strlen .text: 0000555555554CE4 cmp rbx, rax .text: 0000555555554CE7 jnz short loc_555555554D13 .text: 0000555555554CE9 mov ebx, [rbp + var_1CC] .text: 0000555555554CEF lea rax, [rbp + var_30] .text: 0000555555554CF3 mov rdi, rax ; s .text: 0000555555554CF6 call _strlen .text: 0000555555554CFB cmp rbx, rax .text: 0000555555554CFE jnz short loc_555555554D13 .text: 0000555555554D00 cmp [rbp + var_1D0], 5 .text: 0000555555554D07 jbe short loc_555555554D13 .text: 0000555555554D09 mov rax, [rbp + var_1D8] .text: 0000555555554D10 mov byte ptr [rax], 1 .text: 0000555555554D13 .text: 0000555555554D13 loc_555555554D13: ; CODE XREF: challenge2 + 41 ↑j .text: 0000555555554D13 ; challenge2 + 131 ↑j ... .text: 0000555555554D13 mov rax, [rbp + var_18] .text: 0000555555554D17 xor rax, fs: 28h .text: 0000555555554D20 jz short loc_555555554D27 .text: 0000555555554D22 call ___stack_chk_fail .text: 0000555555554D27 ; - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - .text: 0000555555554D27 .text: 0000555555554D27 loc_555555554D27: ; CODE XREF: challenge2 + 16A ↑j .text: 0000555555554D27 add rsp, 1D8h .text: 0000555555554D2E pop rbx .text: 0000555555554D2F pop rbp .text: 0000555555554D30 retn .text: 0000555555554D30 challenge2 endp |
正确的运行逻辑: challenge2 -> loc_555555554BFC -> loc_555555554C6D -> loc_555555554CB8 -> loc_555555554D13 -> loc_555555554D27
对应伪代码:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 | unsigned __int64 __fastcall challenge2(_BYTE * a1) { unsigned int v2; / / [rsp + 10h ] [rbp - 1D0h ] int v3; / / [rsp + 14h ] [rbp - 1CCh ] int v4; / / [rsp + 18h ] [rbp - 1C8h ] int v5; / / [rsp + 1Ch ] [rbp - 1C4h ] struct utsname name; / / [rsp + 20h ] [rbp - 1C0h ] BYREF char s[ 10 ]; / / [rsp + 1A6h ] [rbp - 3Ah ] BYREF char v8[ 24 ]; / / [rsp + 1B0h ] [rbp - 30h ] BYREF unsigned __int64 v9; / / [rsp + 1C8h ] [rbp - 18h ] v9 = __readfsqword( 0x28u ); if ( uname(&name) ) { perror( "uname" ); } else { strcpy(s, "QilingOS" ); strcpy(v8, "ChallengeStart" ); v2 = 0 ; v3 = 0 ; while ( v4 < strlen(s) ) { if ( name.sysname[v4] = = s[v4] ) + + v2; + + v4; } while ( v5 < strlen(v8) ) { if ( name.version[v5] = = v8[v5] ) + + v3; + + v5; } if ( v2 = = strlen(s) && v3 = = strlen(v8) && v2 > 5 ) * a1 = 1 ; } return __readfsqword( 0x28u ) ^ v9; } |
第一个if判断:
1 2 3 4 | if ( uname(&name) ) { perror( "uname" ); } |
uname(&name)
是一个系统调用函数,它的作用是获取当前系统的名称和版本信息,并将这些信息存储到 struct utsname
类型的结构体变量 name
中,name
使用struct utsname name;
声明 ,如果成功获取的话函数返回值为0,就可以进入else了。else中我们最后需要执行*a1 = 1
,这里面有两个循环进行字符串逐个判断,如果相同就能在最后的if判断中让*a1 = 1
。此处我们需要了解uname的结构体,uname的结构为:
1 2 3 4 5 6 7 8 | struct utsname { char sysname[ 65 ]; char nodename[ 65 ]; char release[ 65 ]; char version[ 65 ]; char machine[ 65 ]; char domainname[ 65 ]; }; |
我们需要让name.sysname等于"QilingOS",name.version等于"ChallengeStart"。
出题人提供了源码,可以看到源码的逻辑跟分析的一致:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 | void challenge2(char * check) { unsigned int i, j, k, l; struct utsname name; char qiling_OS[ 10 ]; char chall_start[ 24 ]; if ( uname(&name) ) { perror( "uname" ); } else { strcpy(qiling_OS, "QilingOS" ); strcpy(chall_start, "ChallengeStart" ); i = 0 ; j = 0 ; while ( k < strlen(qiling_OS) ) { if ( name.sysname[k] = = qiling_OS[k] ) + + i; + + k; } while ( l < strlen(chall_start) ) { if ( name.version[l] = = chall_start[l] ) + + j; + + l; } if ( i = = strlen(qiling_OS) && j = = strlen(chall_start) && i > 5 ) * check = 1 ; } } |
根据上述分析,我们需要hook系统调用uname。在Qiling中有四种hook方式,这四个方式都是常量:
- QL_INTERCEPT.EXIT:在系统调用执行完成之后立即执行hook函数
- QL_INTERCEPT.ENTER:在系统调用执行之前执行hook函数
- QL_INTERCEPT.EXIT_TREE:在系统调用执行完成并返回后,执行完其他所有系统调用的hook函数之后再执行当前系统调用的hook函数
- QL_INTERCEPT.EXIT_ALL:在系统调用执行完成并返回后,执行所有系统调用的hook函数
为了使用上面的hook方式,需要使用 from qiling.const import *
导入Qiling模拟器中的常量。
系统调用返回结构体型数据时,会将结构体的地址存放在寄存器rdi中,因此我们需要使用 ql.arch.regs.rdi
得到rdi中存储的uname地址。
writeup 2
writeup:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 | from qiling import * from qiling.const import * # 导入Qiling模拟器中的常量 def my_uname_on_exit_hook(ql, * args): rdi = ql.arch.regs.rdi print (f "utsname address: {hex(rdi)}" ) # utsname address: 0x80000000db50 ql.mem.write(rdi, b 'QilingOS\x00' ) ql.mem.write(rdi + 65 * 3 , b 'ChallengeStart\x00' ) # 000080000000DC13 def challenge2(ql): # 使用QL_INTERCEPT.EXIT在系统调用执行完成之后立即执行hook函数,ql.os.set_syscall 使用方法在官方文档 Hijack 部分 ql.os.set_syscall( "uname" , my_uname_on_exit_hook, QL_INTERCEPT.EXIT) if __name__ = = '__main__' : path = [ "rootfs/x8664_linux/qilinglab-x86_64" ] rootfs = "rootfs/x8664_linux" ql = Qiling(path, rootfs) # 记得加上challenge1 challenge2(ql) ql.run() |
用IDA看一下运行脚本后rdi指向的sysname和version,可以看到已经按照我们的脚本进行了修改:
运行脚本,challenge2已解决:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 | Checking which challenge are solved... [ = ] write(fd = 0x1 , buf = 0x55555575a260 , count = 0x54 ) = 0x54 Note: Some challenges will results in segfaults and infinite loops if they aren't solved. [ = ] write(fd = 0x1 , buf = 0x55555575a260 , count = 0x5a ) = 0x5a [ = ] write(fd = 0x1 , buf = 0x55555575a260 , count = 0x1 ) = 0x1 [ = ] uname(buf = 0x80000000db50 ) = 0x0 Challenge 1 : SOLVED [ = ] write(fd = 0x1 , buf = 0x55555575a260 , count = 0x14 ) = 0x14 [ = ] openat(fd = 0xffffff9c , path = 0x555555555698 , flags = 0x0 , mode = 0x0 ) = - 0x2 (ENOENT) [ = ] read(fd = 0xffffffff , buf = 0x80000000dcc0 , length = 0x20 ) = - 0x9 (EBADF) [ = ] read(fd = 0xffffffff , buf = 0x80000000dcbf , length = 0x1 ) = - 0x9 (EBADF) [ = ] close(fd = 0xffffffff ) = - 0x1 (EPERM) [ = ] getrandom(buf = 0x80000000dce0 , buflen = 0x20 , flags = 0x1 ) = 0x20 Challenge 2 : SOLVED [ = ] write(fd = 0x1 , buf = 0x55555575a260 , count = 0x14 ) = 0x14 Challenge 3 : NOT SOLVED [ = ] write(fd = 0x1 , buf = 0x55555575a260 , count = 0x18 ) = 0x18 [ = ] time() = 0x6471f7b0 Challenge 4 : NOT SOLVED [ = ] write(fd = 0x1 , buf = 0x55555575a260 , count = 0x18 ) = 0x18 |
Challenge 3: 自定义文件对象
Challenge 3: Make '/dev/urandom' and 'getrandom' "collide".
IDA 看一下 Challenge 3:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 | .text: 0000555555554D31 public challenge3 .text: 0000555555554D31 challenge3 proc near ; CODE XREF: start + 16B ↓p .text: 0000555555554D31 .text: 0000555555554D31 var_68 = qword ptr - 68h .text: 0000555555554D31 var_60 = dword ptr - 60h .text: 0000555555554D31 var_5C = dword ptr - 5Ch .text: 0000555555554D31 fd = dword ptr - 58h .text: 0000555555554D31 var_51 = byte ptr - 51h .text: 0000555555554D31 buf = byte ptr - 50h .text: 0000555555554D31 var_30 = byte ptr - 30h .text: 0000555555554D31 var_8 = qword ptr - 8 .text: 0000555555554D31 .text: 0000555555554D31 push rbp .text: 0000555555554D32 mov rbp, rsp .text: 0000555555554D35 sub rsp, 70h .text: 0000555555554D39 mov [rbp + var_68], rdi .text: 0000555555554D3D mov rax, fs: 28h .text: 0000555555554D46 mov [rbp + var_8], rax .text: 0000555555554D4A xor eax, eax .text: 0000555555554D4C mov esi, 0 ; oflag .text: 0000555555554D51 lea rdi, file ; "/dev/urandom" .text: 0000555555554D58 mov eax, 0 .text: 0000555555554D5D call _open .text: 0000555555554D62 mov [rbp + fd], eax .text: 0000555555554D65 lea rcx, [rbp + buf] .text: 0000555555554D69 mov eax, [rbp + fd] .text: 0000555555554D6C mov edx, 20h ; ' ' ; nbytes .text: 0000555555554D71 mov rsi, rcx ; buf .text: 0000555555554D74 mov edi, eax ; fd .text: 0000555555554D76 call _read .text: 0000555555554D7B lea rcx, [rbp + var_51] .text: 0000555555554D7F mov eax, [rbp + fd] .text: 0000555555554D82 mov edx, 1 ; nbytes .text: 0000555555554D87 mov rsi, rcx ; buf .text: 0000555555554D8A mov edi, eax ; fd .text: 0000555555554D8C call _read .text: 0000555555554D91 mov eax, [rbp + fd] .text: 0000555555554D94 mov edi, eax ; fd .text: 0000555555554D96 call _close .text: 0000555555554D9B lea rax, [rbp + var_30] .text: 0000555555554D9F mov edx, 1 .text: 0000555555554DA4 mov esi, 20h ; .text: 0000555555554DA9 mov rdi, rax .text: 0000555555554DAC call _getrandom .text: 0000555555554DB1 mov [rbp + var_60], 0 .text: 0000555555554DB8 mov [rbp + var_5C], 0 .text: 0000555555554DBF jmp short loc_555555554DF3 .text: 0000555555554DC1 ; - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - .text: 0000555555554DC1 .text: 0000555555554DC1 loc_555555554DC1: ; CODE XREF: challenge3 + C6↓j .text: 0000555555554DC1 mov eax, [rbp + var_5C] .text: 0000555555554DC4 cdqe .text: 0000555555554DC6 movzx edx, [rbp + rax + buf] ; edx清零,读取 rbp + rax + buf 地址处的一个字节,并将其扩充到 64 位移入edx寄存器低 8 位 .text: 0000555555554DCB mov eax, [rbp + var_5C] .text: 0000555555554DCE cdqe ; 将 32 位eax值扩展为 64 位rax值 .text: 0000555555554DD0 movzx eax, [rbp + rax + var_30] .text: 0000555555554DD5 cmp dl, al .text: 0000555555554DD7 jnz short loc_555555554DEF .text: 0000555555554DD9 mov eax, [rbp + var_5C] .text: 0000555555554DDC cdqe .text: 0000555555554DDE movzx edx, [rbp + rax + buf] .text: 0000555555554DE3 movzx eax, [rbp + var_51] .text: 0000555555554DE7 cmp dl, al ; di:edx低 8 位,al:eax低 8 位 .text: 0000555555554DE9 jz short loc_555555554DEF .text: 0000555555554DEB add [rbp + var_60], 1 .text: 0000555555554DEF .text: 0000555555554DEF loc_555555554DEF: ; CODE XREF: challenge3 + A6↑j .text: 0000555555554DEF ; challenge3 + B8↑j .text: 0000555555554DEF add [rbp + var_5C], 1 .text: 0000555555554DF3 .text: 0000555555554DF3 loc_555555554DF3: ; CODE XREF: challenge3 + 8E ↑j .text: 0000555555554DF3 cmp [rbp + var_5C], 1Fh .text: 0000555555554DF7 jle short loc_555555554DC1 ; 小于或等于则跳转 .text: 0000555555554DF9 cmp [rbp + var_60], 20h ; .text: 0000555555554DFD jnz short loc_555555554E06 .text: 0000555555554DFF mov rax, [rbp + var_68] .text: 0000555555554E03 mov byte ptr [rax], 1 ; byte ptr是指定操作数的大小,这里是一个byte ; 将字节值 1 存储在rax寄存器指向的内存地址中 .text: 0000555555554E06 .text: 0000555555554E06 loc_555555554E06: ; CODE XREF: challenge3 + CC↑j .text: 0000555555554E06 nop .text: 0000555555554E07 mov rax, [rbp + var_8] .text: 0000555555554E0B xor rax, fs: 28h .text: 0000555555554E14 jz short locret_555555554E1B .text: 0000555555554E16 call ___stack_chk_fail .text: 0000555555554E1B ; - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - .text: 0000555555554E1B .text: 0000555555554E1B locret_555555554E1B: ; CODE XREF: challenge3 + E3↑j .text: 0000555555554E1B leave .text: 0000555555554E1C retn .text: 0000555555554E1C challenge3 endp |
Challenge 3 伪代码:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 | unsigned __int64 __fastcall challenge3(_BYTE * a1) { int v2; / / [rsp + 10h ] [rbp - 60h ] int i; / / [rsp + 14h ] [rbp - 5Ch ] int fd; / / [rsp + 18h ] [rbp - 58h ] char v5; / / [rsp + 1Fh ] [rbp - 51h ] BYREF char buf[ 32 ]; / / [rsp + 20h ] [rbp - 50h ] BYREF char v7[ 40 ]; / / [rsp + 40h ] [rbp - 30h ] BYREF unsigned __int64 v8; / / [rsp + 68h ] [rbp - 8h ] v8 = __readfsqword( 0x28u ); / / 从fs段读取地址 0x28 处的 8 个字节,并将其存储在v8变量中。地址 0x28 处的数据通常被用来存储函数的返回地址 fd = open ( "/dev/urandom" , 0 ); read(fd, buf, 0x20uLL ); read(fd, &v5, 1uLL ); close(fd); getrandom(v7, 32LL , 1LL ); v2 = 0 ; for ( i = 0 ; i < = 31 ; + + i ) { if ( buf[i] = = v7[i] && buf[i] ! = v5 ) + + v2; } if ( v2 = = 32 ) * a1 = 1 ; / / 修改指针所指向的内存中的值 return __readfsqword( 0x28u ) ^ v8; } |
分析程序逻辑,主要关注点在buf,v5与v7三者之间的关系:
1 2 3 4 | read(fd, buf, 0x20uLL ); read(fd, &v5, 1uLL ); ··· getrandom(v7, 32LL , 1LL ); |
read(fd, buf, 0x20uLL)
:从文件描述符fd读取32(0x20)字节的数据,并将其存储在字符数组buf中。原函数:ssize_t read(int fd, void *buf, size_t count);
read(fd, &v5, 1uLL)
:从文件描述符fd读取1字节的数据,并将其存储在字符变量v5中。getrandom(v7, 32LL, 1LL)
:系统调用,从系统提供的随机数源获取随机数据。代码含义是从系统熵池中获取32字节的随机数据,并将其存储在字符数组v7中。
我们需要在i循环中让buf[i]
与v7[i]
相等,且buf[i]
不等于v5
。getrandom是利用系统调用获取随机数,urandom是利用文件读写操作获取随机数,要解决这道题需要让两者一样。关于 /dev/urandom
与 getrandom
的相关知识:
/dev/urandom
是一个 Unix/Linux 系统中的特殊文件,它是一个伪随机数发生器设备文件,用于生成随机数。
在Qiling中使用 ql.add_fs_mapper("/dev/urandom", "/dev/urandom")
将宿主机中的 /dev/urandom (后面的)
设备文件映射到 Qiling 虚拟机中的 /dev/urandom (前面的)
文件上,以便为虚拟机中的程序提供随机数服务。
getrandom使用方法:
1 2 3 4 5 6 7 8 9 10 11 12 | getrandom(ql, buf, buflen, flags) buf:指向缓冲区的指针,用于存储读取到的随机数据。 buflen:要从系统熵池读取的字节数。 flags:指定 getrandom 函数的行为。常见的 flags 值包括: 0 :如果系统熵池中没有足够的熵,getrandom 会阻塞直到有足够的熵可用。 GRND_NONBLOCK(通常为 1 ):getrandom 在系统熵池中没有足够的熵时,会立即返回错误而不是阻塞。 GRND_RANDOM(通常为 2 ):尝试从 / dev / random 获取随机数据,而不是从 / dev / urandom 获取。这个选项会导致 getrandom 的行为更加谨慎,可能会在熵不足时阻塞。 返回值: 如果成功获取随机数据,getrandom 返回实际读取的字节数。 如果出错,返回 - 1 并设置 errno。常见的错误包括 EAGAIN(系统熵池中没有足够的熵,且 flags 设置为非阻塞模式)和 EFAULT(buf 指针无效或指向不可访问的内存区域)。 |
我们可以使用QlFsMappedObject自定义文件对象,实现"/dev/urandom":
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 | from qiling import Qiling from qiling.os.mapper import QlFsMappedObject class FakeUrandom(QlFsMappedObject): def read( self , size: int ) - > bytes: if size = = 1 : return b "\x42" # v5的长度为1 # return a constant value upon reading else : return b "\x41" def fstat( self ) - > int : # fstat() 是Linux/Unix系统调用之一,用来获取文件的状态信息 # return -1 to let syscall fstat ignore it return - 1 def close( self ) - > int : return 0 if __name__ = = "__main__" : ql = Qiling([r 'rootfs/x86_linux/bin/x86_fetch_urandom' ], r 'rootfs/x86_linux' ) ql.add_fs_mapper(r '/dev/urandom' , FakeUrandom()) ql.run() |
我们可以通过hook系统调用自定义一个"getrandom",例如:
1 2 3 4 5 6 7 8 9 10 11 12 | def hook_getrandom(ql, buf, buflen, flags): # 自定义 getrandom 函数实现 if buflen = = 32 : data = b '\x41' * buflen # b'\x41' = A ql.mem.write(buf, data) ql.os.set_syscall_return(buflen) else : ql.os.set_syscall_return( - 1 ) ··· # 调用自定义系统调用 ql.os.set_syscall( "getrandom" , hook_getrandom) |
writeup 3
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 | from qiling import * from qiling.const import * # 导入Qiling模拟器中的常量 from qiling.os.mapper import QlFsMappedObject class FakeUrandom(QlFsMappedObject): def read( self , size: int ) - > bytes: if size = = 1 : return b "\x42" else : return b "\x41" * size def close( self ) - > int : return 0 def hook_getrandom(ql, buf, buflen, flags): # 自定义 getrandom 函数实现 if buflen = = 32 : data = b '\x41' * buflen # b'\x41' = A ql.mem.write(buf, data) ql.os.set_syscall_return(buflen) else : ql.os.set_syscall_return( - 1 ) def challenge3(ql): ql.add_fs_mapper(r '/dev/urandom' , FakeUrandom()) ql.os.set_syscall( "getrandom" , hook_getrandom) if __name__ = = '__main__' : path = [ "rootfs/x8664_linux/qilinglab-x86_64" ] rootfs = "rootfs/x8664_linux" ql = Qiling(path, rootfs) # 记得加上challenge1 challenge2(ql) ql.run() |
运行后,可以看到challenge 3已解决:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 | Checking which challenge are solved... [ = ] write(fd = 0x1 , buf = 0x55555575a260 , count = 0x54 ) = 0x54 Note: Some challenges will results in segfaults and infinite loops if they aren't solved. [ = ] write(fd = 0x1 , buf = 0x55555575a260 , count = 0x5a ) = 0x5a [ = ] write(fd = 0x1 , buf = 0x55555575a260 , count = 0x1 ) = 0x1 utsname address: 0x80000000db50 [ = ] uname(buf = 0x80000000db50 ) = 0x0 Challenge 1 : SOLVED [ = ] write(fd = 0x1 , buf = 0x55555575a260 , count = 0x14 ) = 0x14 [ = ] openat(fd = 0xffffff9c , path = 0x555555555698 , flags = 0x0 , mode = 0x0 ) = 0x3 [ = ] read(fd = 0x3 , buf = 0x80000000dcc0 , length = 0x20 ) = 0x20 [ = ] read(fd = 0x3 , buf = 0x80000000dcbf , length = 0x1 ) = 0x1 [ = ] close(fd = 0x3 ) = 0x0 [ = ] getrandom(buf = 0x80000000dce0 , buflen = 0x20 , flags = 0x1 ) = ? Challenge 2 : SOLVED [ = ] write(fd = 0x1 , buf = 0x55555575a260 , count = 0x14 ) = 0x14 Challenge 3 : SOLVED [ = ] write(fd = 0x1 , buf = 0x55555575a260 , count = 0x14 ) = 0x14 [ = ] time() = 0x6472521d Challenge 4 : NOT SOLVED [ = ] write(fd = 0x1 , buf = 0x55555575a260 , count = 0x18 ) = 0x18 |
Challenge 4:hook特定地址
Challenge 4: Enter inside the "forbidden" loop.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 | .text: 0000555555554E1D public challenge4 .text: 0000555555554E1D challenge4 proc near ; CODE XREF: start + 18F ↓p .text: 0000555555554E1D .text: 0000555555554E1D var_18 = qword ptr - 18h .text: 0000555555554E1D var_8 = dword ptr - 8 .text: 0000555555554E1D var_4 = dword ptr - 4 .text: 0000555555554E1D .text: 0000555555554E1D push rbp .text: 0000555555554E1E mov rbp, rsp .text: 0000555555554E21 mov [rbp + var_18], rdi .text: 0000555555554E25 mov [rbp + var_8], 0 .text: 0000555555554E2C mov [rbp + var_4], 0 .text: 0000555555554E33 jmp short loc_555555554E40 .text: 0000555555554E35 ; - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - .text: 0000555555554E35 .text: 0000555555554E35 loc_555555554E35: ; CODE XREF: challenge4 + 29 ↓j .text: 0000555555554E35 mov rax, [rbp + var_18] .text: 0000555555554E39 mov byte ptr [rax], 1 .text: 0000555555554E3C add [rbp + var_4], 1 .text: 0000555555554E40 .text: 0000555555554E40 loc_555555554E40: ; CODE XREF: challenge4 + 16 ↑j .text: 0000555555554E40 mov eax, [rbp + var_8] .text: 0000555555554E43 cmp [rbp + var_4], eax .text: 0000555555554E46 jl short loc_555555554E35 ; 小于则跳转 .text: 0000555555554E48 nop .text: 0000555555554E49 pop rbp .text: 0000555555554E4A retn .text: 0000555555554E4A challenge4 endp |
IDA 查看伪代码发现什么都看不到:
1 2 3 4 | __int64 challenge4() { return 0LL ; } |
根据汇编逻辑,我们最终需要实现 mov byte ptr [rax], 1
,但是在 loc_555555554E40 中 :
1 2 3 4 5 6 7 8 | mov [rbp + var_8], 0 mov [rbp + var_4], 0 ··· mov eax, [rbp + var_8] cmp [rbp + var_4], eax add [rbp + var_4], 1 |
实际上就是 0比0,我们需要让[rbp+var_4]
小于[rbp+var_8]
,jl指令才会跳转到loc_555555554E35函数中,执行*a=1
,然后再通过 add [rbp+var_4], 1
跳出循环。
我们根据逻辑patch汇编使得 [rbp+var_8], 1
,就可以得到正确的伪代码:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 | __int64 __fastcall challenge4(_BYTE * a1) { __int64 result; / / rax int i; / / [rsp + 14h ] [rbp - 4h ] for ( i = 0 ; ; + + i ) / / for 循环运行一次后让 * a1 = 1 ,接着 break 。 { result = 1LL ; if ( i > = 1 ) break ; * a1 = 1 ; } return result; } |
可以看到我们的分析是正确的,接着就来编写 Qiling challenge 4 writeup:
writeup 4
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 | def enter_forbidden_loop_hook(ql): ql.arch.regs.eax = 1 def challenge4(ql): """ .text:0000555555554E40 mov eax, [rbp+var_8] .text:0000555555554E43 cmp [rbp+var_4], eax <-- 在运行此命令前hook eax,使得eax = 1 .text:0000555555554E46 jl short loc_555555554E35 """ base = ql.mem.get_lib_base(os.path.split(ql.path)[ - 1 ]) # 根据文件路径查找已经加载的文件,获取对应文件的基地址 # os.path.split(ql.path):os.path.split 函数将 ql.path 分成两部分:目录名和基本文件名。这个函数返回一个包含这两部分的元组。 # os.path.split(ql.path)[-1]:这将返回元组中的最后一个元素,即基本文件名。在 Python 中,-1 索引表示列表或元组的最后一个元素。 # base = ql.mem.get_lib_base(os.path.split(ql.path)[-1]):ql.mem.get_lib_base 函数使用提取的文件名作为参数,以获取已加载库的基地址。将返回的基地址赋值给变量 base hook_addr = base + 0xE43 ql.hook_address(enter_forbidden_loop_hook, hook_addr) # 当执行流程到达hook_addr时,该函数将被调用。此时hook_addr处的代码还未被执行。 |
运行后,可以看到 challenge 4 已经被解决:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 | Challenge 1 : SOLVED [ = ] write(fd = 0x1 , buf = 0x55555575a260 , count = 0x14 ) = 0x14 [ = ] openat(fd = 0xffffff9c , path = 0x555555555698 , flags = 0x0 , mode = 0x0 ) = 0x3 [ = ] read(fd = 0x3 , buf = 0x80000000dcc0 , length = 0x20 ) = 0x20 [ = ] read(fd = 0x3 , buf = 0x80000000dcbf , length = 0x1 ) = 0x1 [ = ] close(fd = 0x3 ) = 0x0 [ = ] getrandom(buf = 0x80000000dce0 , buflen = 0x20 , flags = 0x1 ) = ? Challenge 2 : SOLVED [ = ] write(fd = 0x1 , buf = 0x55555575a260 , count = 0x14 ) = 0x14 Challenge 3 : SOLVED [ = ] write(fd = 0x1 , buf = 0x55555575a260 , count = 0x14 ) = 0x14 [ = ] time() = 0x64730987 Challenge 4 : SOLVED [ = ] write(fd = 0x1 , buf = 0x55555575a260 , count = 0x14 ) = 0x14 |
Challenge 5:hook函数调用
Challenge 5: Guess every call to rand().
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 | .text: 0000555555554E4B public challenge5 .text: 0000555555554E4B challenge5 proc near ; CODE XREF: start + 1B3 ↓p .text: 0000555555554E4B .text: 0000555555554E4B var_58 = qword ptr - 58h .text: 0000555555554E4B var_48 = dword ptr - 48h .text: 0000555555554E4B var_44 = dword ptr - 44h .text: 0000555555554E4B var_40 = dword ptr - 40h .text: 0000555555554E4B var_20 = dword ptr - 20h .text: 0000555555554E4B var_8 = qword ptr - 8 .text: 0000555555554E4B .text: 0000555555554E4B push rbp .text: 0000555555554E4C mov rbp, rsp .text: 0000555555554E4F sub rsp, 60h .text: 0000555555554E53 mov [rbp + var_58], rdi .text: 0000555555554E57 mov rax, fs: 28h .text: 0000555555554E60 mov [rbp + var_8], rax .text: 0000555555554E64 xor eax, eax .text: 0000555555554E66 mov edi, 0 ; timer .text: 0000555555554E6B call _time .text: 0000555555554E70 mov edi, eax ; seed .text: 0000555555554E72 call _srand .text: 0000555555554E77 mov [rbp + var_48], 0 .text: 0000555555554E7E jmp short loc_555555554EA1 .text: 0000555555554E80 ; - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - .text: 0000555555554E80 .text: 0000555555554E80 loc_555555554E80: ; CODE XREF: challenge5 + 5A ↓j .text: 0000555555554E80 mov eax, [rbp + var_48] .text: 0000555555554E83 cdqe .text: 0000555555554E85 mov [rbp + rax * 4 + var_40], 0 .text: 0000555555554E8D call _rand .text: 0000555555554E92 mov edx, eax .text: 0000555555554E94 mov eax, [rbp + var_48] .text: 0000555555554E97 cdqe .text: 0000555555554E99 mov [rbp + rax * 4 + var_20], edx .text: 0000555555554E9D add [rbp + var_48], 1 .text: 0000555555554EA1 .text: 0000555555554EA1 loc_555555554EA1: ; CODE XREF: challenge5 + 33 ↑j .text: 0000555555554EA1 cmp [rbp + var_48], 4 .text: 0000555555554EA5 jle short loc_555555554E80 .text: 0000555555554EA7 mov [rbp + var_44], 0 .text: 0000555555554EAE jmp short loc_555555554ED3 .text: 0000555555554EB0 ; - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - .text: 0000555555554EB0 .text: 0000555555554EB0 loc_555555554EB0: ; CODE XREF: challenge5 + 8C ↓j .text: 0000555555554EB0 mov eax, [rbp + var_44] .text: 0000555555554EB3 cdqe .text: 0000555555554EB5 mov edx, [rbp + rax * 4 + var_40] .text: 0000555555554EB9 mov eax, [rbp + var_44] .text: 0000555555554EBC cdqe .text: 0000555555554EBE mov eax, [rbp + rax * 4 + var_20] .text: 0000555555554EC2 cmp edx, eax .text: 0000555555554EC4 jz short loc_555555554ECF .text: 0000555555554EC6 mov rax, [rbp + var_58] .text: 0000555555554ECA mov byte ptr [rax], 0 .text: 0000555555554ECD jmp short loc_555555554EE0 .text: 0000555555554ECF ; - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - .text: 0000555555554ECF .text: 0000555555554ECF loc_555555554ECF: ; CODE XREF: challenge5 + 79 ↑j .text: 0000555555554ECF add [rbp + var_44], 1 .text: 0000555555554ED3 .text: 0000555555554ED3 loc_555555554ED3: ; CODE XREF: challenge5 + 63 ↑j .text: 0000555555554ED3 cmp [rbp + var_44], 4 .text: 0000555555554ED7 jle short loc_555555554EB0 .text: 0000555555554ED9 mov rax, [rbp + var_58] .text: 0000555555554EDD mov byte ptr [rax], 1 .text: 0000555555554EE0 .text: 0000555555554EE0 loc_555555554EE0: ; CODE XREF: challenge5 + 82 ↑j .text: 0000555555554EE0 mov rax, [rbp + var_8] .text: 0000555555554EE4 xor rax, fs: 28h .text: 0000555555554EED jz short locret_555555554EF4 .text: 0000555555554EEF call ___stack_chk_fail .text: 0000555555554EF4 ; - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - .text: 0000555555554EF4 .text: 0000555555554EF4 locret_555555554EF4: ; CODE XREF: challenge5 + A2↑j .text: 0000555555554EF4 leave .text: 0000555555554EF5 retn .text: 0000555555554EF5 challenge5 endp |
challenge 5 伪代码如下:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 | unsigned __int64 __fastcall challenge5(_BYTE * a1) { unsigned int v1; / / eax int i; / / [rsp + 18h ] [rbp - 48h ] int j; / / [rsp + 1Ch ] [rbp - 44h ] int v5[ 14 ]; / / [rsp + 20h ] [rbp - 40h ] unsigned __int64 v6; / / [rsp + 58h ] [rbp - 8h ] v6 = __readfsqword( 0x28u ); v1 = time( 0LL ); srand(v1); / / srand 使用时间作为种子,生成真正的随机数 for ( i = 0 ; i < = 4 ; + + i ) { v5[i] = 0 ; / / 0 , 1 , 2 , 3 , 4 v5[i + 8 ] = rand(); / / 8 , 9 , 19 , 11 , 12 } for ( j = 0 ; j < = 4 ; + + j ) / / 我们需要绕过此循环 { if ( v5[j] ! = v5[j + 8 ] ) { * a1 = 0 ; return __readfsqword( 0x28u ) ^ v6; } } * a1 = 1 ; return __readfsqword( 0x28u ) ^ v6; } |
分析代码逻辑,我们想要最后得到*a1 = 1
的话,需要绕过第二个for循环。让rand()得到的值都为0就可以了。hook方法在官方手册 Hijacking OS API (POSIX) 。
writeup 5
1 2 3 4 5 | def hook_rand(ql): ql.arch.regs.rax = 0 # 在x86-64架构中,函数的返回值通常保存在RAX寄存器中。rand函数的返回值会存储在rax寄存器 def challenge5(ql): ql.os.set_api( 'rand' , hook_rand) |
运行后没有显示第五个挑战是否被解决,因为被第六题的死循环卡住了。
Challenge 6:修改寄存器值
Challenge 6: Avoid the infinite loop.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 | .text: 0000555555554EF6 public challenge6 .text: 0000555555554EF6 challenge6 proc near ; CODE XREF: start + 1D7 ↓p .text: 0000555555554EF6 .text: 0000555555554EF6 var_18 = qword ptr - 18h .text: 0000555555554EF6 var_5 = byte ptr - 5 .text: 0000555555554EF6 var_4 = dword ptr - 4 .text: 0000555555554EF6 .text: 0000555555554EF6 push rbp .text: 0000555555554EF7 mov rbp, rsp .text: 0000555555554EFA mov [rbp + var_18], rdi .text: 0000555555554EFE mov [rbp + var_4], 0 .text: 0000555555554F05 mov [rbp + var_5], 1 .text: 0000555555554F09 jmp short loc_555555554F12 .text: 0000555555554F0B ; - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - .text: 0000555555554F0B .text: 0000555555554F0B loc_555555554F0B: ; CODE XREF: challenge6 + 22 ↓j .text: 0000555555554F0B mov [rbp + var_4], 1 .text: 0000555555554F12 .text: 0000555555554F12 loc_555555554F12: ; CODE XREF: challenge6 + 13 ↑j .text: 0000555555554F12 movzx eax, [rbp + var_5] .text: 0000555555554F16 test al, al ; 不修改al的内容,只更新标志位 .text: 0000555555554F18 jnz short loc_555555554F0B ; ZF = 0 则跳转loc_555555554F0B函数 .text: 0000555555554F1A mov rax, [rbp + var_18] .text: 0000555555554F1E mov byte ptr [rax], 1 .text: 0000555555554F21 nop .text: 0000555555554F22 pop rbp .text: 0000555555554F23 retn .text: 0000555555554F23 challenge6 endp |
查看伪代码,可以看到跟第四题一样:
1 2 3 4 5 | void challenge6() { while ( 1 ) ; } |
我们需要执行loc_555555554F0B函数,然后再退出循环。我们需要让ZF=0,jnz才能跳转loc_555555554F0B函数。
主要关注点在test al, al
上,这条指令的含义是将EAX的低8位(al)与自身与运算,主要是用于修改ZF标志位。
1 2 3 4 5 | test al, al = al & al 由于操作数 al 相同,所以运算结果必然是 al 本身的值。 根据运算结果值是否为 0 ,ZF 标志位会被设置为: 结果为 0 :ZF = 1 结果不为 0 :ZF = 0 |
因此我们需要将eax设置为0,对mov [rbp+var_5], 1
进行patch,改为 mov [rbp+var_5], 0
,就可以正确生成伪代码了,得到的和我们预期的一致。
1 2 3 4 | void __fastcall challenge6(_BYTE * a1) { * a1 = 1 ; } |
writeup 6
1 2 3 4 5 6 | def hook_rax(ql): ql.arch.regs.rax = 0 def challenge6(ql): base = ql.mem.get_lib_base(os.path.split(ql.path)[ - 1 ]) hook_addr = base + 0xF16 ql.hook_address(hook_rax, hook_addr) |
运行后可以看到第五个挑战已经解决,但是第六个还没显示,应该是需要解出第七题:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 | Challenge 1 : SOLVED [ = ] write(fd = 0x1 , buf = 0x55555575a260 , count = 0x14 ) = 0x14 [ = ] openat(fd = 0xffffff9c , path = 0x555555555698 , flags = 0x0 , mode = 0x0 ) = 0x3 [ = ] read(fd = 0x3 , buf = 0x80000000dcc0 , length = 0x20 ) = 0x20 [ = ] read(fd = 0x3 , buf = 0x80000000dcbf , length = 0x1 ) = 0x1 [ = ] close(fd = 0x3 ) = 0x0 [ = ] getrandom(buf = 0x80000000dce0 , buflen = 0x20 , flags = 0x1 ) = ? Challenge 2 : SOLVED [ = ] write(fd = 0x1 , buf = 0x55555575a260 , count = 0x14 ) = 0x14 Challenge 3 : SOLVED [ = ] write(fd = 0x1 , buf = 0x55555575a260 , count = 0x14 ) = 0x14 [ = ] time() = 0x64732fa5 Challenge 4 : SOLVED [ = ] write(fd = 0x1 , buf = 0x55555575a260 , count = 0x14 ) = 0x14 Challenge 5 : SOLVED [ = ] write(fd = 0x1 , buf = 0x55555575a260 , count = 0x14 ) = 0x14 |
Challenge 7:hook函数调用
Challenge 7: Don't waste time waiting for 'sleep'.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 | .text: 0000555555554F24 public challenge7 .text: 0000555555554F24 challenge7 proc near ; CODE XREF: start + 1FB ↓p .text: 0000555555554F24 .text: 0000555555554F24 var_8 = qword ptr - 8 .text: 0000555555554F24 .text: 0000555555554F24 push rbp .text: 0000555555554F25 mov rbp, rsp .text: 0000555555554F28 sub rsp, 10h .text: 0000555555554F2C mov [rbp + var_8], rdi .text: 0000555555554F30 mov rax, [rbp + var_8] .text: 0000555555554F34 mov byte ptr [rax], 1 .text: 0000555555554F37 mov edi, 0FFFFFFFFh ; seconds .text: 0000555555554F3C call _sleep ; < - - - - - - - hook .text: 0000555555554F41 nop .text: 0000555555554F42 leave .text: 0000555555554F43 retn .text: 0000555555554F43 challenge7 endp |
伪代码如下:
1 2 3 4 5 | unsigned int __fastcall challenge7(_BYTE * a1) { * a1 = 1 ; return sleep( 0xFFFFFFFF ); } |
我们可以利用之前学的方法hook sleep函数,还是比较简单的。
writeup 7
1 2 3 4 | def hook_sleep(ql): return 0 def challenge7(ql): ql.os.set_api( 'sleep' , hook_sleep) |
运行后,可以看到1-7题已解决:
1 2 3 4 | [ = ] write(fd = 0x1 , buf = 0x55555575a260 , count = 0x19 ) = 0x19 You solved 7 / 11 of the challenges [ = ] write(fd = 0x1 , buf = 0x55555575a260 , count = 0x22 ) = 0x22 [ = ] exit_group(code = 0x0 ) = ? |
Challenge 8:修改结构体的值
Challenge 8: Unpack the struct and write at the target address.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 | .text: 0000555555554F44 public challenge8 .text: 0000555555554F44 challenge8 proc near ; CODE XREF: start + 21F ↓p .text: 0000555555554F44 .text: 0000555555554F44 var_18 = qword ptr - 18h .text: 0000555555554F44 var_8 = qword ptr - 8 .text: 0000555555554F44 .text: 0000555555554F44 push rbp .text: 0000555555554F45 mov rbp, rsp .text: 0000555555554F48 sub rsp, 20h .text: 0000555555554F4C mov [rbp + var_18], rdi .text: 0000555555554F50 mov edi, 18h ; size .text: 0000555555554F55 call _malloc .text: 0000555555554F5A mov [rbp + var_8], rax .text: 0000555555554F5E mov edi, 1Eh ; size .text: 0000555555554F63 call _malloc .text: 0000555555554F68 mov rdx, rax .text: 0000555555554F6B mov rax, [rbp + var_8] .text: 0000555555554F6F mov [rax], rdx .text: 0000555555554F72 mov rax, [rbp + var_8] .text: 0000555555554F76 mov dword ptr [rax + 8 ], 539h .text: 0000555555554F7D mov rax, [rbp + var_8] .text: 0000555555554F81 movss xmm0, cs:dword_555555555A98 .text: 0000555555554F89 movss dword ptr [rax + 0Ch ], xmm0 .text: 0000555555554F8E mov rax, [rbp + var_8] .text: 0000555555554F92 mov rax, [rax] .text: 0000555555554F95 mov rcx, 64206D6F646E6152h .text: 0000555555554F9F mov [rax], rcx .text: 0000555555554FA2 mov dword ptr [rax + 8 ], 617461h .text: 0000555555554FA9 mov rax, [rbp + var_8] .text: 0000555555554FAD mov rdx, [rbp + var_18] .text: 0000555555554FB1 mov [rax + 10h ], rdx .text: 0000555555554FB5 nop .text: 0000555555554FB6 leave .text: 0000555555554FB7 retn .text: 0000555555554FB7 challenge8 endp |
伪代码如下:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 | _DWORD * __fastcall challenge8(__int64 a1) { _DWORD * result; / / rax _DWORD * v2; / / [rsp + 18h ] [rbp - 8h ] v2 = malloc( 0x18uLL ); / / 调用malloc函数,请求分配 0x18 字节( 24 字节)的内存。分配成功后,指向分配内存的指针被赋值给变量v2 * (_QWORD * )v2 = malloc( 0x1EuLL ); / / 调用malloc函数,请求分配 0x1E 字节( 30 字节)的内存。 / / 将返回的指针(指向分配的 30 字节内存块)存储在v2所指向的内存中的前 8 个字节( 64 位系统一个指针大小为 8 字节,即一个_QWORD) v2[ 2 ] = 1337 ; v2[ 3 ] = 1039980266 ; strcpy( * (char * * )v2, "Random data" ); result = v2; * ((_QWORD * )v2 + 2 ) = a1; return result; } |
v2是一个指针,指向malloc分配的内存块,相当于结构体的头指针,结构体整理后的内容如下:
1 2 3 4 5 6 | typedef struct { char * string_ptr; / / 8 字节的指针,指向字符串 "Random data" 所在的内存 uint32_t value1; / / 4 字节的整数,值为 1337 uint32_t value2; / / 4 字节的整数,值为 1039980266 int64_t a1; / / 8 字节的整数,值为传入的参数 a1 } CustomStruct; |
我们需要修改*a1
为1,我使用的是以下方法对程序运行时存在的魔数进行搜索来判断结构体头指针位置,进而根据对应地址进行修改:
writeup 8
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 | import struct def challenge8_hook(ql): # 在内存中寻找魔数 MAGIC = 0x3DFCD6EA00000539 ''' 魔数由结构体中 value1 与 value2 构成。 1. 将 value1 转换为 16 进制表示:1337 的 16 进制表示为 0x539。 2. 将 value2 转换为 16 进制表示:1039980266 的 16 进制表示为 0x3DFCD6EA。 3. 将 value2 字段左移 32 位,这相当于将其乘以 2^32:0x3DFCD6EA * 2^32 = 0x3DFCD6EA00000000。 4. 将 value2 与 alue1 的值相加:0x3DFCD6EA00000000 + 0x539 = 0x3DFCD6EA00000539。 所以,将 value1 和 value2 字段组合得到的魔数是 0x3DFCD6EA00000539。 ''' magic_addrs = ql.mem.search(ql.pack64(MAGIC)) # 转换魔数成为字节序列 for magic_addr in magic_addrs: # 为了避免重复,循环检测 # Dump and unpack the candidate structure candidate_heap_struct_addr = magic_addr - 8 # 魔数距离堆头指针距离为 8 bytes candidate_heap_struct = ql.mem.read(candidate_heap_struct_addr, 24 ) # 获取结构体地址结构 string_addr, _ , check_addr = struct.unpack( 'QQQ' , candidate_heap_struct) # struct.unpack() 是一个 Python 函数,用于将字节序列解包为多个值,解包 candidate_heap_struct 地址结构。 # 'QQQ' 是一个格式字符串,表示要解包的数据结构包含3个64位(8 字节)无符号整数。 # string_addr, _ , check_addr:只关注 string_addr 与 check_addr,最后得到相应地址 if ql.mem.string(string_addr) = = "Random data" : # 修改*a1为1 ql.mem.write(check_addr, b "\x01" ) break def challenge8(ql): base_addr = ql.mem.get_lib_base(os.path.split(ql.path)[ - 1 ]) end_of_challenge8 = base_addr + 0xFB5 # 程序运行结束时的地址 ql.hook_address(challenge8_hook, end_of_challenge8) |
运行后可以看到第八题已解出:
1 2 3 | You solved 8 / 11 of the challenges [ = ] write(fd = 0x1 , buf = 0x55555575a260 , count = 0x22 ) = 0x22 [ = ] exit_group(code = 0x0 ) = ? |
Challenge 9: hook函数调用
Challenge 9: Fix some string operation to make the iMpOsSiBlE come true.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 | .text: 0000555555554FB8 public challenge9 .text: 0000555555554FB8 challenge9 proc near ; CODE XREF: start + 243 ↓p .text: 0000555555554FB8 .text: 0000555555554FB8 var_68 = qword ptr - 68h .text: 0000555555554FB8 var_58 = qword ptr - 58h .text: 0000555555554FB8 dest = byte ptr - 50h .text: 0000555555554FB8 src = byte ptr - 30h .text: 0000555555554FB8 var_28 = qword ptr - 28h .text: 0000555555554FB8 var_20 = qword ptr - 20h .text: 0000555555554FB8 var_18 = dword ptr - 18h .text: 0000555555554FB8 var_8 = qword ptr - 8 .text: 0000555555554FB8 .text: 0000555555554FB8 push rbp .text: 0000555555554FB9 mov rbp, rsp .text: 0000555555554FBC sub rsp, 70h .text: 0000555555554FC0 mov [rbp + var_68], rdi .text: 0000555555554FC4 mov rax, fs: 28h .text: 0000555555554FCD mov [rbp + var_8], rax .text: 0000555555554FD1 xor eax, eax .text: 0000555555554FD3 mov rax, cs:qword_5555555556A5 .text: 0000555555554FDA mov rdx, cs:qword_5555555556AD .text: 0000555555554FE1 mov qword ptr [rbp + src], rax .text: 0000555555554FE5 mov [rbp + var_28], rdx .text: 0000555555554FE9 mov rax, cs:qword_5555555556B5 .text: 0000555555554FF0 mov [rbp + var_20], rax .text: 0000555555554FF4 mov eax, cs:dword_5555555556BD .text: 0000555555554FFA mov [rbp + var_18], eax .text: 0000555555554FFD lea rdx, [rbp + src] .text: 0000555555555001 lea rax, [rbp + dest] .text: 0000555555555005 mov rsi, rdx ; src .text: 0000555555555008 mov rdi, rax ; dest .text: 000055555555500B call _strcpy .text: 0000555555555010 lea rax, [rbp + dest] .text: 0000555555555014 mov [rbp + var_58], rax .text: 0000555555555018 jmp short loc_555555555038 .text: 000055555555501A ; - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - .text: 000055555555501A .text: 000055555555501A loc_55555555501A: ; CODE XREF: challenge9 + 89 ↓j .text: 000055555555501A mov rax, [rbp + var_58] .text: 000055555555501E movzx eax, byte ptr [rax] .text: 0000555555555021 movsx eax, al .text: 0000555555555024 mov edi, eax ; c .text: 0000555555555026 call _tolower .text: 000055555555502B mov edx, eax .text: 000055555555502D mov rax, [rbp + var_58] .text: 0000555555555031 mov [rax], dl .text: 0000555555555033 add [rbp + var_58], 1 .text: 0000555555555038 .text: 0000555555555038 loc_555555555038: ; CODE XREF: challenge9 + 60 ↑j .text: 0000555555555038 mov rax, [rbp + var_58] .text: 000055555555503C movzx eax, byte ptr [rax] .text: 000055555555503F test al, al .text: 0000555555555041 jnz short loc_55555555501A .text: 0000555555555043 lea rdx, [rbp + dest] .text: 0000555555555047 lea rax, [rbp + src] .text: 000055555555504B mov rsi, rdx ; s2 .text: 000055555555504E mov rdi, rax ; s1 .text: 0000555555555051 call _strcmp .text: 0000555555555056 test eax, eax .text: 0000555555555058 setz dl .text: 000055555555505B mov rax, [rbp + var_68] .text: 000055555555505F mov [rax], dl .text: 0000555555555061 nop .text: 0000555555555062 mov rax, [rbp + var_8] .text: 0000555555555066 xor rax, fs: 28h .text: 000055555555506F jz short locret_555555555076 .text: 0000555555555071 call ___stack_chk_fail .text: 0000555555555076 ; - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - .text: 0000555555555076 .text: 0000555555555076 locret_555555555076: ; CODE XREF: challenge9 + B7↑j .text: 0000555555555076 leave .text: 0000555555555077 retn .text: 0000555555555077 challenge9 endp |
伪代码为:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 | unsigned __int64 __fastcall challenge9( bool * a1) { char * i; / / [rsp + 18h ] [rbp - 58h ] char dest[ 32 ]; / / [rsp + 20h ] [rbp - 50h ] BYREF char src[ 40 ]; / / [rsp + 40h ] [rbp - 30h ] BYREF unsigned __int64 v5; / / [rsp + 68h ] [rbp - 8h ] v5 = __readfsqword( 0x28u ); strcpy(src, "aBcdeFghiJKlMnopqRstuVWxYz" ); strcpy(dest, src); for ( i = dest; * i; + + i ) * i = tolower( * i); * a1 = strcmp(src, dest) = = 0 ; return __readfsqword( 0x28u ) ^ v5; } |
根据代码,我们需要让 strcmp(src, dest) == 0
,strcmp(str1,str2) 如果str1 == str2
,则返回 0。
tolower函数是将给定的字符转换为小写形式。我们可以通过hook tolower让tolower失效,strcmp自然能够顺利对比一致。
writeup 9
1 2 3 4 | def hook_tolower(ql): return 0 def challenge9(ql): ql.os.set_api( 'tolower' , hook_tolower) |
运行后顺利通过:
1 2 3 | You solved 9 / 11 of the challenges [ = ] write(fd = 0x1 , buf = 0x55555575a260 , count = 0x22 ) = 0x22 [ = ] exit_group(code = 0x0 ) = ? |
Challenge 10:自定义文件对象
Challenge 10: Fake the 'cmdline' line file to return the right content.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 | .text: 0000555555555078 public challenge10 .text: 0000555555555078 challenge10 proc near ; CODE XREF: start + 267 ↓p .text: 0000555555555078 .text: 0000555555555078 var_68 = qword ptr - 68h .text: 0000555555555078 var_60 = dword ptr - 60h .text: 0000555555555078 fd = dword ptr - 5Ch .text: 0000555555555078 var_58 = qword ptr - 58h .text: 0000555555555078 buf = byte ptr - 50h .text: 0000555555555078 var_8 = qword ptr - 8 .text: 0000555555555078 .text: 0000555555555078 push rbp .text: 0000555555555079 mov rbp, rsp .text: 000055555555507C sub rsp, 70h .text: 0000555555555080 mov [rbp + var_68], rdi .text: 0000555555555084 mov rax, fs: 28h .text: 000055555555508D mov [rbp + var_8], rax .text: 0000555555555091 xor eax, eax .text: 0000555555555093 mov esi, 0 ; oflag .text: 0000555555555098 lea rdi, aProcSelfCmdlin ; "/proc/self/cmdline" .text: 000055555555509F mov eax, 0 .text: 00005555555550A4 call _open .text: 00005555555550A9 mov [rbp + fd], eax .text: 00005555555550AC cmp [rbp + fd], 0FFFFFFFFh .text: 00005555555550B0 jz loc_55555555513F .text: 00005555555550B6 lea rcx, [rbp + buf] .text: 00005555555550BA mov eax, [rbp + fd] .text: 00005555555550BD mov edx, 3Fh ; '?' ; nbytes .text: 00005555555550C2 mov rsi, rcx ; buf .text: 00005555555550C5 mov edi, eax ; fd .text: 00005555555550C7 call _read .text: 00005555555550CC mov [rbp + var_58], rax .text: 00005555555550D0 cmp [rbp + var_58], 0 .text: 00005555555550D5 jle short loc_555555555142 .text: 00005555555550D7 mov eax, [rbp + fd] .text: 00005555555550DA mov edi, eax ; fd .text: 00005555555550DC call _close .text: 00005555555550E1 mov [rbp + var_60], 0 .text: 00005555555550E8 jmp short loc_555555555106 .text: 00005555555550EA ; - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - .text: 00005555555550EA .text: 00005555555550EA loc_5555555550EA: ; CODE XREF: challenge10 + 97 ↓j .text: 00005555555550EA mov eax, [rbp + var_60] .text: 00005555555550ED cdqe .text: 00005555555550EF movzx eax, [rbp + rax + buf] .text: 00005555555550F4 test al, al .text: 00005555555550F6 jnz short loc_555555555102 .text: 00005555555550F8 mov eax, [rbp + var_60] .text: 00005555555550FB cdqe .text: 00005555555550FD mov [rbp + rax + buf], 20h ; ' ' .text: 0000555555555102 .text: 0000555555555102 loc_555555555102: ; CODE XREF: challenge10 + 7E ↑j .text: 0000555555555102 add [rbp + var_60], 1 .text: 0000555555555106 .text: 0000555555555106 loc_555555555106: ; CODE XREF: challenge10 + 70 ↑j .text: 0000555555555106 mov eax, [rbp + var_60] .text: 0000555555555109 cdqe .text: 000055555555510B cmp [rbp + var_58], rax .text: 000055555555510F jg short loc_5555555550EA ; 大于则跳转 .text: 0000555555555111 lea rdx, [rbp + buf] .text: 0000555555555115 mov rax, [rbp + var_58] .text: 0000555555555119 add rax, rdx .text: 000055555555511C mov byte ptr [rax], 0 .text: 000055555555511F lea rax, [rbp + buf] .text: 0000555555555123 lea rsi, s2 ; "qilinglab" .text: 000055555555512A mov rdi, rax ; s1 .text: 000055555555512D call _strcmp .text: 0000555555555132 test eax, eax .text: 0000555555555134 jnz short loc_555555555143 .text: 0000555555555136 mov rax, [rbp + var_68] .text: 000055555555513A mov byte ptr [rax], 1 .text: 000055555555513D jmp short loc_555555555143 .text: 000055555555513F ; - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - .text: 000055555555513F .text: 000055555555513F loc_55555555513F: ; CODE XREF: challenge10 + 38 ↑j .text: 000055555555513F nop .text: 0000555555555140 jmp short loc_555555555143 .text: 0000555555555142 ; - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - .text: 0000555555555142 .text: 0000555555555142 loc_555555555142: ; CODE XREF: challenge10 + 5D ↑j .text: 0000555555555142 nop .text: 0000555555555143 .text: 0000555555555143 loc_555555555143: ; CODE XREF: challenge10 + BC↑j .text: 0000555555555143 ; challenge10 + C5↑j ... .text: 0000555555555143 mov rax, [rbp + var_8] .text: 0000555555555147 xor rax, fs: 28h .text: 0000555555555150 jz short locret_555555555157 .text: 0000555555555152 call ___stack_chk_fail .text: 0000555555555157 ; - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - .text: 0000555555555157 .text: 0000555555555157 locret_555555555157: ; CODE XREF: challenge10 + D8↑j .text: 0000555555555157 leave .text: 0000555555555158 retn .text: 0000555555555158 challenge10 endp |
对应伪代码为:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 | unsigned __int64 __fastcall challenge10(_BYTE * a1) { int i; / / [rsp + 10h ] [rbp - 60h ] int fd; / / [rsp + 14h ] [rbp - 5Ch ] ssize_t v4; / / [rsp + 18h ] [rbp - 58h ] char buf[ 72 ]; / / [rsp + 20h ] [rbp - 50h ] BYREF unsigned __int64 v6; / / [rsp + 68h ] [rbp - 8h ] v6 = __readfsqword( 0x28u ); fd = open ( "/proc/self/cmdline" , 0 ); if ( fd ! = - 1 ) { v4 = read(fd, buf, 0x3FuLL ); if ( v4 > 0 ) { close(fd); for ( i = 0 ; v4 > i; + + i ) { if ( !buf[i] ) buf[i] = 32 ; } buf[v4] = 0 ; if ( !strcmp(buf, "qilinglab" ) ) * a1 = 1 ; } } return __readfsqword( 0x28u ) ^ v6; } |
根据代码,我们需要让 buf 等于 "qilinglab"。
fd:open失败为-1,open成功为0。
/proc/self/cmdline是一个在Linux系统中的特殊文件,它提供了当前进程(即访问/proc/self/cmdline的进程)的命令行参数信息。
假如我们使用命令./my_program arg1 arg2 arg3
启动一个程序时,读取/proc/self/cmdline的过程在 ./my_program
中,/proc/self/cmdline文件的内容将是:
1 | . / my_program\ 0arg1 \ 0arg2 \ 0arg3 \ 0 |
按照第三个挑战的方法,我们可以使用自定义文件对象来更改读取文件时的返回值:
writeup 10
1 2 3 4 5 6 7 8 9 | class Fake_cmdline(QlFsMappedObject): def read( self , expected_len): return b 'qilinglab' def close( self ): return 0 def challenge10(ql): ql.add_fs_mapper( '/proc/self/cmdline' , Fake_cmdline()) |
在运行后并没有解题成功,好像是在hook /proc/self/cmdline
这里存在问题,我写了个脚本单独调试以下cmdline读取程序:
c 程序:用来读取cmdline,文件名:test_cmdline
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 | #include <stdio.h> #include <stdlib.h> int main() { FILE * file ; char ch; / / 打开 / proc / self / cmdline文件 file = fopen( "/proc/self/cmdline" , "r" ); if ( file = = NULL) { printf( "无法打开/proc/self/cmdline文件。\n" ); exit(EXIT_FAILURE); } printf( "读取/proc/self/cmdline:\n" ); / / 逐个字符读取文件内容并输出到终端 while ((ch = fgetc( file )) ! = EOF) { / / 将空字符替换为换行符以提高可读性 if (ch = = '\0' ) { putchar( '\n' ); } else { putchar(ch); } } / / 关闭文件 fclose( file ); return 0 ; } |
python程序:用来hook test_cmdline 中的文件操作
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 | from qiling import * from qiling.const import * from qiling.os.mapper import QlFsMappedObject from qiling.const import QL_INTERCEPT from qiling.os.const import STRING import struct import os class Fake_cmdline(QlFsMappedObject): def read( self , expected_len): return b 'qilinglab' def close( self ): return 0 def challenge10(ql): ql.add_fs_mapper( '/proc/self/cmdline' , Fake_cmdline()) if __name__ = = '__main__' : path = [ "test_cmdline" ] rootfs = "rootfs/x8664_linux" ql = Qiling(path, rootfs) challenge10(ql) ql.run() |
运行结果如下,可以看到确实在读取操作的过程中存在问题。
1 2 3 4 5 6 7 8 | 读取 / proc / self / cmdline: [ = ] write(fd = 0x1 , buf = 0x55555555b490 , count = 0x1c ) = 0x1c [ = ] fstat(fd = 0x3 , buf_ptr = 0x80000000dc50 ) = - 0x1 (EPERM) [ = ] read(fd = 0x3 , buf = 0x55555555b8a0 , length = 0x2000 ) = 0xd test_cmdline [ = ] write(fd = 0x1 , buf = 0x55555555b490 , count = 0xd ) = 0xd [ = ] read(fd = 0x3 , buf = 0x55555555b8a0 , length = 0x2000 ) = 0x0 [ = ] close(fd = 0x3 ) = 0x0 |
切换到 Qilinglab当时使用的版本看一下是否存在这个问题,Qilinglab的文章是21年7月发的,对应Qiling版本应该是1.2.4,使用pip指定版本安装方法:
1 | pip install Qiling = = 1.2 . 4 |
运行后存在版本不兼容问题,因此我将从这个版本开始直到最新版的每个版本都进行了测试。结果如下:
1.4.3 可以正确进行文件映射:
1 2 | Challenge 10 : SOLVED [ = ] write(fd = 0x1 , buf = 0x55555575a260 , count = 0x15 ) = 0x15 |
1.4.4 无法正确进行文件映射:
1 2 | Challenge 10 : NOT SOLVED [ = ] write(fd = 0x1 , buf = 0x55555575a260 , count = 0x19 ) = 0x19 |
我们使用的最新版是 1.4.5,也就是说在1.4.3到1.4.4这个版本更新中可能存在问题,因此接下来进行代码审计。文件映射在源码对应的 qiling/os/mapper.py
中,我们对比一下文件改动:
改动如下:
- 新增 QlFsMappedCallable
- 由 inspect.isclass(real_dest) 扩展到 callable(real_dest)
- 由 real_path 更改为 host_path
- 新增 ql.fs_mapper.add_fs_mapping() 方法,使用 ql.add_fs_mapper() (QlFsMapper 的实例)进行调用,能够卸载映射的文件
第1点:
在之前,Qiling只支持字符串和对象做为文件系统映射。而QlFsMappedCallable允许用户传入一个类对象real_dest,然后在调用时实例化这个类对象。
用于 add_fs_mapping(self, ql_path: Union[os.PathLike, str], real_dest: Union[str, QlFsMappedObject, QlFsMappedCallable])
。
第2点:
- isclass 只检查类
- callable 可以检查函数和类
第3点:
- Guest 程序指的是在 Qiling 框架下被模拟执行的程序
- real_path 是 Guest 程序运行时所使用的路径
- host_path 是可以被 Guest 程序打开的 Host 系统中的一个路径
第4点:
- 属于新增能够卸载映射的文件的功能
我们替换1.4.4的mapper.py为1.4.3版本,
1 | vim / home / ubuntu / anaconda3 / envs / ql1 - 4 - 4 / lib / python3. 9 / site - packages / qiling / os / mapper.py |
更改后依然没变化,报错。接着分析是否是针对 /proc/self/cmdline
有新的处理方式,加载1.4.4的源码到vscode中,发现在 linux.py
文件中新增以下代码:
看一下更新对比:
1.4.4版本的linux.py文件与1.4.3版本的linux.py文件相比,有以下主要改动:
- 添加了setup_procfs()方法,用于设置/proc伪文件系统。这使得Qiling可以模拟/proc目录和相关文件,提供更真实的linux环境。
- /proc/self目录下的几个文件(auxv、cmdline、environ、exe、maps)被映射到QlProcFS类的静态方法上,这使得Qiling可以模拟读取这几个文件。
- run()方法中,除非是处理驱动程序或shellcode,否则都会调用setup_procfs()设置/proc文件系统。这确保除特殊情况外,Qiling都会模拟/proc文件系统。
- 添加了fs_mapper属性,用于管理文件系统映射。setup_procfs()就是通过fs_mapper添加/proc文件系统映射的。
之前在1.4.3版本中模拟/proc目录的方式有两个:
- 直接读取/proc文件内容
- 通过QlFsMappedCallable映射/proc文件,返回自定义内容
这两种方式存在一定缺点:
- 无法方便地重用/proc内容,需要多次读取
- 映射时需要定义QlFsMappedCallable类,很麻烦,处理方式不统一
所以总的来说1.4.4版本对/proc处理做了封装,使得它更模块化、易用。但是在新增的几个模块中对 '/proc/self/auxv' 等文件做出了额外的限制,我们在映射这几个文件时可能存在问题。因此我怀疑 cmdline 的问题就是在这个地方。
接着看run(self)函数:
1 2 3 4 | def run( self ): # do not set-up procfs for drivers and shellcode if not self .ql.code and not self .ql.loader.is_driver: self .setup_procfs() |
这段代码的含义是:
只有在加载ELF文件或可执行程序的时候,才设置/proc文件系统。
- 对于直接加载Shellcode(
self.ql.code
)的情况,不设置/proc文件系统 - 对于加载驱动程序 (
self.ql.loader.is_driver
) 的情况,也不设置/proc文件系统
1 | vim / home / ubuntu / anaconda3 / envs / ql1 - 4 - 4 / lib / python3. 9 / site - packages / qiling / os / linux / linux.py |
因此将此处判断代码注释后,就应该可以成功运行了。注释后运行:
1 2 3 4 5 6 7 8 9 | Challenge 8 : SOLVED [ = ] write(fd = 0x1 , buf = 0x55555575a260 , count = 0x14 ) = 0x14 [ = ] openat(fd = 0xffffff9c , path = 0x5555555556c1 , flags = 0x0 , mode = 0x0 ) = 0x3 [ = ] read(fd = 0x3 , buf = 0x80000000dcc0 , length = 0x3f ) = 0x9 [ = ] close(fd = 0x3 ) = 0x0 Challenge 9 : SOLVED [ = ] write(fd = 0x1 , buf = 0x55555575a260 , count = 0x14 ) = 0x14 Challenge 10 : SOLVED [ = ] write(fd = 0x1 , buf = 0x55555575a260 , count = 0x15 ) = 0x15 |
运行成功!
这个问题应该在1.4.4和1.4.5中都存在,我们可以通过新增一个选项 ql = Qiling(path, rootfs, enable_procfs=False)
来控制是否设置/proc文件系统,当enable_procfs=False
时关闭,默认值为True。我们需要修改 core.py
文件:
1 | vim / home / ubuntu / anaconda3 / envs / ql1 - 4 - 4 / lib / python3. 9 / site - packages / qiling / core.py |
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 | def __init__( self , argv: Sequence[ str ] = None , rootfs: str = r '.' , env: MutableMapping[AnyStr, AnyStr] = {}, code: bytes = None , ostype: Union[ str , QL_OS] = None , archtype: Union[ str , QL_ARCH] = None , verbose: QL_VERBOSE = QL_VERBOSE.DEFAULT, profile: str = None , console: bool = True , log_file = None , log_override = None , log_plain: bool = False , multithread: bool = False , filter = None , stop: QL_STOP = QL_STOP.NONE, * , endian: Optional[QL_ENDIAN] = None , thumb: bool = False , libcache: bool = False , enable_procfs: bool = True # <---------------------------- 新添加的参数,默认值为True ): self .enable_procfs = enable_procfs # <---------------------------- 设置 enable_procfs 属性 ······ |
修改 linux.py
中的代码新增对参数enable_procfs的判断:
1 2 3 4 | def run( self ): # if not self.ql.code and not self.ql.loader.is_driver: # 原来的代码 if self .ql.enable_procfs and not self .ql.code and not self .ql.loader.is_driver: self .setup_procfs() |
这样我们只需要将ql改成下面的代码即可:
1 | ql = Qiling(path, rootfs, enable_procfs = False ) |
然后修改我们的challenge10测试一下,运行成功!
1 2 3 4 5 6 7 8 9 | Challenge 8 : SOLVED [ = ] write(fd = 0x1 , buf = 0x55555575a260 , count = 0x14 ) = 0x14 [ = ] openat(fd = 0xffffff9c , path = 0x5555555556c1 , flags = 0x0 , mode = 0x0 ) = 0x3 [ = ] read(fd = 0x3 , buf = 0x80000000dcc0 , length = 0x3f ) = 0x9 [ = ] close(fd = 0x3 ) = 0x0 Challenge 9 : SOLVED [ = ] write(fd = 0x1 , buf = 0x55555575a260 , count = 0x14 ) = 0x14 Challenge 10 : SOLVED [ = ] write(fd = 0x1 , buf = 0x55555575a260 , count = 0x15 ) = 0x15 |
Challenge 11:绕过CPUID校验
Challenge 11: Bypass CPUID/MIDR_EL1 checks.
伪代码如下:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 | unsigned __int64 __fastcall challenge11(_BYTE * a1) { int v7; / / [rsp + 1Ch ] [rbp - 34h ] int v8; / / [rsp + 24h ] [rbp - 2Ch ] char s[ 4 ]; / / [rsp + 2Bh ] [rbp - 25h ] BYREF char v10[ 4 ]; / / [rsp + 2Fh ] [rbp - 21h ] BYREF char v11[ 4 ]; / / [rsp + 33h ] [rbp - 1Dh ] BYREF unsigned __int64 v12; / / [rsp + 38h ] [rbp - 18h ] v12 = __readfsqword( 0x28u ); _RAX = 0x40000000LL ; __asm { cpuid } v7 = _RCX; v8 = _RDX; if ( __PAIR64__(_RBX, _RCX) = = 0x696C6951614C676ELL && (_DWORD)_RDX = = 538976354 ) * a1 = 1 ; sprintf( s, "%c%c%c%c" , (unsigned int )_RBX, (unsigned int )(( int )_RBX >> 8 ), (unsigned int )(( int )_RBX >> 16 ), (unsigned int )(( int )_RBX >> 24 )); sprintf( v10, "%c%c%c%c" , (unsigned int )v7, (unsigned int )(v7 >> 8 ), (unsigned int )(v7 >> 16 ), (unsigned int )(v7 >> 24 )); sprintf( v11, "%c%c%c%c" , (unsigned int )v8, (unsigned int )(v8 >> 8 ), (unsigned int )(v8 >> 16 ), (unsigned int )(v8 >> 24 )); return __readfsqword( 0x28u ) ^ v12; } |
关键部分汇编代码如下:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 | .text: 000055555555518F cpuid .text: 0000555555555191 mov eax, edx .text: 0000555555555193 mov esi, ebx .text: 0000555555555195 mov [rbp + var_30], esi .text: 0000555555555198 mov [rbp + var_34], ecx .text: 000055555555519B mov [rbp + var_2C], eax .text: 000055555555519E cmp [rbp + var_30], 696C6951h .text: 00005555555551A5 jnz short loc_5555555551C0 .text: 00005555555551A7 cmp [rbp + var_34], 614C676Eh .text: 00005555555551AE jnz short loc_5555555551C0 .text: 00005555555551B0 cmp [rbp + var_2C], 20202062h .text: 00005555555551B7 jnz short loc_5555555551C0 .text: 00005555555551B9 mov rax, [rbp + var_48] .text: 00005555555551BD mov byte ptr [rax], 1 |
我们需要让*a=1
,就要让if的判断顺利通过,if ( __PAIR64__(_RBX, _RCX) == 0x696C6951614C676ELL && (_DWORD)_RDX == 538976354 )
的含义为:
- rbx和rcx两个32位寄存器组成的64位值等于0x696C6951614C676ELL
- RDX寄存器的低32位等于538976354
因此我们跳过cpuid指令修改寄存器即可。
writeup 11
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 | def hook_cpuid(ql, address, size): if ql.mem.read(address, size) = = b '\x0F\xA2' : # CPUID指令的机器码是 0F A2 regs = ql.arch.regs regs.ebx = 0x696C6951 regs.ecx = 0x614C676E regs.edx = 0x20202062 regs.rip + = 2 # 跳过cpuid指令防止被cpuid篡改 000055555555518F -> 0000555555555191 def challenge11(ql): begin, end = 0 , 0 for info in ql.mem.map_info: print (info) if info[ 2 ] = = 5 and 'qilinglab-x86_64' in info[ 3 ]: begin, end = info[: 2 ] print (f "{begin} -> {end}" ) ql.hook_code(hook_cpuid, begin = begin, end = end) |
最后可以看到全部题目均已解决:
1 2 3 | You solved 11 / 11 of the challenges [ = ] write(fd = 0x1 , buf = 0x55555575a260 , count = 0x23 ) = 0x23 [ = ] exit_group(code = 0x0 ) = ? |
最后完整的代码为:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 | from qiling import * from qiling.const import * from qiling.os.mapper import QlFsMappedObject from qiling.const import QL_INTERCEPT from qiling.os.const import STRING from qiling.os.mapper import QlFsMappedCallable import struct import os def challenge1(ql): ql.mem. map ( 0x1000 , 0x1000 , info = '[challenge1]' ) ql.mem.write( 0x1337 , ql.pack16( 1337 )) def my_uname_on_exit_hook(ql, * args): rdi = ql.arch.regs.rdi print (f "utsname address: {hex(rdi)}" ) ql.mem.write(rdi, b 'QilingOS\x00' ) ql.mem.write(rdi + 65 * 3 , b 'ChallengeStart\x00' ) def challenge2(ql): ql.os.set_syscall( "uname" , my_uname_on_exit_hook, QL_INTERCEPT.EXIT) class FakeUrandom(QlFsMappedObject): def read( self , size: int ) - > bytes: if size = = 1 : print ( "*************3**************" ) return b "\x42" else : return b "\x41" * size def close( self ) - > int : return 0 def hook_getrandom(ql, buf, buflen, flags): # 自定义 getrandom 函数实现 if buflen = = 32 : data = b '\x41' * buflen # b'\x41' = A ql.mem.write(buf, data) ql.os.set_syscall_return(buflen) else : ql.os.set_syscall_return( - 1 ) def challenge3(ql): ql.add_fs_mapper(r '/dev/urandom' , FakeUrandom()) ql.os.set_syscall( "getrandom" , hook_getrandom) def enter_forbidden_loop_hook(ql): ql.arch.regs.eax = 1 def challenge4(ql): """ .text:0000555555554E40 mov eax, [rbp+var_8] .text:0000555555554E43 cmp [rbp+var_4], eax <-- 在运行此命令前hook eax,使得eax = 1 .text:0000555555554E46 jl short loc_555555554E35 """ base = ql.mem.get_lib_base(os.path.split(ql.path)[ - 1 ]) # 根据文件路径查找已经加载的文件,获取对应文件的基地址 hook_addr = base + 0xE43 ql.hook_address(enter_forbidden_loop_hook, hook_addr) # 当执行流程到达hook_addr时,该函数将被调用。此时hook_addr处的代码还未被执行。 def hook_rand(ql): ql.arch.regs.rax = 0 def challenge5(ql): ql.os.set_api( 'rand' , hook_rand) def hook_rax(ql): ql.arch.regs.rax = 0 def challenge6(ql): base = ql.mem.get_lib_base(os.path.split(ql.path)[ - 1 ]) hook_addr = base + 0xF16 ql.hook_address(hook_rax, hook_addr) def hook_sleep(ql): return 0 def challenge7(ql): ql.os.set_api( 'sleep' , hook_sleep) def challenge8_hook(ql): # Find all occurrences of the magic in memory MAGIC = 0x3DFCD6EA00000539 magic_addrs = ql.mem.search(ql.pack64(MAGIC)) for magic_addr in magic_addrs: # Dump and unpack the candidate structure candidate_heap_struct_addr = magic_addr - 8 candidate_heap_struct = ql.mem.read(candidate_heap_struct_addr, 24 ) string_addr, _ , check_addr = struct.unpack( 'QQQ' , candidate_heap_struct) # struct.unpack() 是一个 Python 函数,用于将字节序列解包为多个值,解包 candidate_heap_struct 变量中的数据。 # 'QQQ' 是一个格式字符串,表示要解包的数据结构包含3个64位(8 字节)无符号整数。 # string_addr, _ , check_addr:只关注 string_addr 与 check_addr if ql.mem.string(string_addr) = = "Random data" : # 修改*a1为1 ql.mem.write(check_addr, b "\x01" ) break def challenge8(ql): base_addr = ql.mem.get_lib_base(os.path.split(ql.path)[ - 1 ]) end_of_challenge8 = base_addr + 0xFB5 # 程序运行结束时的地址 ql.hook_address(challenge8_hook, end_of_challenge8) def hook_tolower(ql): return 0 def challenge9(ql): ql.os.set_api( 'tolower' , hook_tolower) class Fake_cmdline(QlFsMappedObject): def read( self , expected_len): return b 'qilinglab' def close( self ): return 0 def challenge10(ql): # ql.add_fs_mapper('/proc/self/cmdline', Fake_cmdline()) ql.add_fs_mapper( '/proc/self/cmdline' , QlFsMappedCallable(Fake_cmdline)) def hook_cpuid(ql, address, size): if ql.mem.read(address, size) = = b '\x0F\xA2' : regs = ql.arch.regs regs.ebx = 0x696C6951 regs.ecx = 0x614C676E regs.edx = 0x20202062 regs.rip + = 2 def challenge11(ql): begin, end = 0 , 0 for info in ql.mem.map_info: print (info) if info[ 2 ] = = 5 and 'qilinglab-x86_64' in info[ 3 ]: begin, end = info[: 2 ] print (f "{begin} -> {end}" ) ql.hook_code(hook_cpuid, begin = begin, end = end) if __name__ = = '__main__' : path = [ "rootfs/x8664_linux/qilinglab-x86_64" ] rootfs = "rootfs/x8664_linux" ql = Qiling(path, rootfs, enable_procfs = False ) challenge1(ql) challenge2(ql) challenge3(ql) challenge4(ql) challenge5(ql) challenge6(ql) challenge7(ql) challenge8(ql) challenge9(ql) challenge10(ql) challenge11(ql) ql.run() |
总结
跟着上面的文章思路走一遍,我相信大家已经了解了 Qiling 框架的使用方法。通过攥写本文时分析 Qiling 的源码,也加强了我对 Qiling框架的理解。
如果在文中发现问题,欢迎大家在下面留言。
参考文章
Qiling 官方文档
Qiling lab
Qiling Framework入门,11个挑战快速上手@PJXRocks
浅尝qiling框架-qilinglab writeup@badmonkey
11个小挑战,Qiling Framework 入门上手跟练@Cr0ssx2
[培训]二进制漏洞攻防(第3期);满10人开班;模糊测试与工具使用二次开发;网络协议漏洞挖掘;Linux内核漏洞挖掘与利用;AOSP漏洞挖掘与利用;代码审计。
赞赏
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有一个图挂了,补下。
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胡一米 有一个图挂了,补下。好的,已检查全文补齐图片 |
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感谢分享
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写得好,感谢分享
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很有耐心~
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