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[原创]某内测中拳头公司的fps手游GName算法逆向
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发表于: 2024-10-10 11:09
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0x0 序言
前段时间研究了一下某游戏的GName算法，水一篇文章记录一下，以下简称该游戏为C手游。
0x1 静态分析
首先先dump并修复libUE4.so，拖进IDA看一下。ida解析完成后，搜ByteProperty，找到引用的函数 
正常来说找函数调用，这个函数的参数就是全局变量FNamePool的指针，也就是GName，但是C手游的查引用后发现，只有一个函数sub_562B820调用过这个sub_5627A0C
其中这个v1就是本该是一个GName的值，再对sub_562B820查一次调用，随便进去一个函数，发现sub_562B820这个函数的返回值貌似返回的就是fnamePool的地址
1 2 | //sub_562B20的返回算法return *(_QWORD *)(byte_9B0A620[(unsigned int)off_9B0A6A0] | (unsigned __int64)(unsigned __int16)(byte_9B0A620[dword_9B0A6A4] << 8) | ((unsigned __int64)byte_9B0A620[dword_9B0A6A8] << 16) & 0xFFFF000000FFFFFFLL | (byte_9B0A620[(unsigned int)off_9B0A6AC] << 24) | ((unsigned __int64)byte_9B0A620[dword_9B0A6B0] << 32) & 0xFFFF00FFFFFFFFFFLL | ((unsigned __int64)byte_9B0A620[dword_9B0A6B4] << 40) | ((unsigned __int64)byte_9B0A620[dword_9B0A6B8] << 48) | ((unsigned __int64)byte_9B0A620[(unsigned int)off_9B0A6BC] << 56)); |
猜测他是通过byte_9B0A620这个数组，以一定的算法去动态生成FNamePool的地址，不像其他UE4游戏，内存中没有指向他的全局变量。
0x2 动态分析
那既然静态分析完了，那就实际来验证一下这个想法对不对吧。
首先先搜一下ByteProperty
找到FNamePool，然后搜索一下0x7325610000引用，果然没有全局变量指向这个地址。对这个地址下个断点，查一下调用栈
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 | [13432|13587] event_addr:0x7325610000 hit_count:320, Backtrace: #00 pc 000000000562aeb4 /data/app/~~xxx_xxxxxxxxxxx==/com.xxxxxxx.xxxx.xxxxx-xxxxxxxxxxxxxxx==/lib/arm64/libUE4.so #01 pc 000000000562cf34 /data/app/~~xxx_xxxxxxxxxxx==/com.xxxxxxx.xxxx.xxxxx-xxxxxxxxxxxxxxx==/lib/arm64/libUE4.so #02 pc 00000000059db020 /data/app/~~xxx_xxxxxxxxxxx==/com.xxxxxxx.xxxx.xxxxx-xxxxxxxxxxxxxxx==/lib/arm64/libUE4.so #03 pc 0000000003dac2dc /data/app/~~xxx_xxxxxxxxxxx==/com.xxxxxxx.xxxx.xxxxx-xxxxxxxxxxxxxxx==/lib/arm64/libUE4.so #04 pc 00000000059e29c0 /data/app/~~xxx_xxxxxxxxxxx==/com.xxxxxxx.xxxx.xxxxx-xxxxxxxxxxxxxxx==/lib/arm64/libUE4.so #05 pc 0000000006cb6fe0 /data/app/~~xxx_xxxxxxxxxxx==/com.xxxxxxx.xxxx.xxxxx-xxxxxxxxxxxxxxx==/lib/arm64/libUE4.so #06 pc 00000000058dc80c /data/app/~~xxx_xxxxxxxxxxx==/com.xxxxxxx.xxxx.xxxxx-xxxxxxxxxxxxxxx==/lib/arm64/libUE4.so #07 pc 00000000057b92dc /data/app/~~xxx_xxxxxxxxxxx==/com.xxxxxxx.xxxx.xxxxx-xxxxxxxxxxxxxxx==/lib/arm64/libUE4.so #08 pc 00000000057b9410 /data/app/~~xxx_xxxxxxxxxxx==/com.xxxxxxx.xxxx.xxxxx-xxxxxxxxxxxxxxx==/lib/arm64/libUE4.so #09 pc 0000000005876ecc /data/app/~~xxx_xxxxxxxxxxx==/com.xxxxxxx.xxxx.xxxxx-xxxxxxxxxxxxxxx==/lib/arm64/libUE4.so #10 pc 00000000057ae080 /data/app/~~xxx_xxxxxxxxxxx==/com.xxxxxxx.xxxx.xxxxx-xxxxxxxxxxxxxxx==/lib/arm64/libUE4.so #11 pc 00000000058de858 /data/app/~~xxx_xxxxxxxxxxx==/com.xxxxxxx.xxxx.xxxxx-xxxxxxxxxxxxxxx==/lib/arm64/libUE4.so #12 pc 00000000058de1ac /data/app/~~xxx_xxxxxxxxxxx==/com.xxxxxxx.xxxx.xxxxx-xxxxxxxxxxxxxxx==/lib/arm64/libUE4.so #13 pc 00000000058dde28 /data/app/~~xxx_xxxxxxxxxxx==/com.xxxxxxx.xxxx.xxxxx-xxxxxxxxxxxxxxx==/lib/arm64/libUE4.so #14 pc 00000000058dc814 /data/app/~~xxx_xxxxxxxxxxx==/com.xxxxxxx.xxxx.xxxxx-xxxxxxxxxxxxxxx==/lib/arm64/libUE4.so #15 pc 00000000057b92dc /data/app/~~xxx_xxxxxxxxxxx==/com.xxxxxxx.xxxx.xxxxx-xxxxxxxxxxxxxxx==/lib/arm64/libUE4.so #16 pc 00000000057b9410 /data/app/~~xxx_xxxxxxxxxxx==/com.xxxxxxx.xxxx.xxxxx-xxxxxxxxxxxxxxx==/lib/arm64/libUE4.so #17 pc 0000000005876ecc /data/app/~~xxx_xxxxxxxxxxx==/com.xxxxxxx.xxxx.xxxxx-xxxxxxxxxxxxxxx==/lib/arm64/libUE4.so #18 pc 00000000058681b0 /data/app/~~xxx_xxxxxxxxxxx==/com.xxxxxxx.xxxx.xxxxx-xxxxxxxxxxxxxxx==/lib/arm64/libUE4.so #19 pc 00000000057ae080 /data/app/~~xxx_xxxxxxxxxxx==/com.xxxxxxx.xxxx.xxxxx-xxxxxxxxxxxxxxx==/lib/arm64/libUE4.so #20 pc 00000000058de858 /data/app/~~xxx_xxxxxxxxxxx==/com.xxxxxxx.xxxx.xxxxx-xxxxxxxxxxxxxxx==/lib/arm64/libUE4.so #21 pc 00000000058de1ac /data/app/~~xxx_xxxxxxxxxxx==/com.xxxxxxx.xxxx.xxxxx-xxxxxxxxxxxxxxx==/lib/arm64/libUE4.so #22 pc 00000000058dde28 /data/app/~~xxx_xxxxxxxxxxx==/com.xxxxxxx.xxxx.xxxxx-xxxxxxxxxxxxxxx==/lib/arm64/libUE4.so #23 pc 00000000058dc814 /data/app/~~xxx_xxxxxxxxxxx==/com.xxxxxxx.xxxx.xxxxx-xxxxxxxxxxxxxxx==/lib/arm64/libUE4.so #24 pc 00000000057b92dc /data/app/~~xxx_xxxxxxxxxxx==/com.xxxxxxx.xxxx.xxxxx-xxxxxxxxxxxxxxx==/lib/arm64/libUE4.so #25 pc 00000000057b9410 /data/app/~~xxx_xxxxxxxxxxx==/com.xxxxxxx.xxxx.xxxxx-xxxxxxxxxxxxxxx==/lib/arm64/libUE4.so #26 pc 0000000005876ecc /data/app/~~xxx_xxxxxxxxxxx==/com.xxxxxxx.xxxx.xxxxx-xxxxxxxxxxxxxxx==/lib/arm64/libUE4.so #27 pc 00000000057ae080 /data/app/~~xxx_xxxxxxxxxxx==/com.xxxxxxx.xxxx.xxxxx-xxxxxxxxxxxxxxx==/lib/arm64/libUE4.so #28 pc 00000000058de858 /data/app/~~xxx_xxxxxxxxxxx==/com.xxxxxxx.xxxx.xxxxx-xxxxxxxxxxxxxxx==/lib/arm64/libUE4.so #29 pc 00000000058de1ac /data/app/~~xxx_xxxxxxxxxxx==/com.xxxxxxx.xxxx.xxxxx-xxxxxxxxxxxxxxx==/lib/arm64/libUE4.so #30 pc 00000000058dde28 /data/app/~~xxx_xxxxxxxxxxx==/com.xxxxxxx.xxxx.xxxxx-xxxxxxxxxxxxxxx==/lib/arm64/libUE4.so #31 pc 00000000058dc814 /data/app/~~xxx_xxxxxxxxxxx==/com.xxxxxxx.xxxx.xxxxx-xxxxxxxxxxxxxxx==/lib/arm64/libUE4.so #32 pc 00000000057b92dc /data/app/~~xxx_xxxxxxxxxxx==/com.xxxxxxx.xxxx.xxxxx-xxxxxxxxxxxxxxx==/lib/arm64/libUE4.so #33 pc 00000000057b9410 /data/app/~~xxx_xxxxxxxxxxx==/com.xxxxxxx.xxxx.xxxxx-xxxxxxxxxxxxxxx==/lib/arm64/libUE4.so #34 pc 0000000005876ecc /data/app/~~xxx_xxxxxxxxxxx==/com.xxxxxxx.xxxx.xxxxx-xxxxxxxxxxxxxxx==/lib/arm64/libUE4.so #35 pc 00000000058681b0 /data/app/~~xxx_xxxxxxxxxxx==/com.xxxxxxx.xxxx.xxxxx-xxxxxxxxxxxxxxx==/lib/arm64/libUE4.so #36 pc 00000000057ae080 /data/app/~~xxx_xxxxxxxxxxx==/com.xxxxxxx.xxxx.xxxxx-xxxxxxxxxxxxxxx==/lib/arm64/libUE4.so #37 pc 00000000058de858 /data/app/~~xxx_xxxxxxxxxxx==/com.xxxxxxx.xxxx.xxxxx-xxxxxxxxxxxxxxx==/lib/arm64/libUE4.so #38 pc 00000000058de1ac /data/app/~~xxx_xxxxxxxxxxx==/com.xxxxxxx.xxxx.xxxxx-xxxxxxxxxxxxxxx==/lib/arm64/libUE4.so #39 pc 00000000058dde28 /data/app/~~xxx_xxxxxxxxxxx==/com.xxxxxxx.xxxx.xxxxx-xxxxxxxxxxxxxxx==/lib/arm64/libUE4.so #40 pc 00000000058dc814 /data/app/~~xxx_xxxxxxxxxxx==/com.xxxxxxx.xxxx.xxxxx-xxxxxxxxxxxxxxx==/lib/arm64/libUE4.so #41 pc 00000000057b92dc /data/app/~~xxx_xxxxxxxxxxx==/com.xxxxxxx.xxxx.xxxxx-xxxxxxxxxxxxxxx==/lib/arm64/libUE4.so #42 pc 00000000057b9410 /data/app/~~xxx_xxxxxxxxxxx==/com.xxxxxxx.xxxx.xxxxx-xxxxxxxxxxxxxxx==/lib/arm64/libUE4.so #43 pc 0000000005876ecc /data/app/~~xxx_xxxxxxxxxxx==/com.xxxxxxx.xxxx.xxxxx-xxxxxxxxxxxxxxx==/lib/arm64/libUE4.so #44 pc 00000000057ae080 /data/app/~~xxx_xxxxxxxxxxx==/com.xxxxxxx.xxxx.xxxxx-xxxxxxxxxxxxxxx==/lib/arm64/libUE4.so #45 pc 00000000058de858 /data/app/~~xxx_xxxxxxxxxxx==/com.xxxxxxx.xxxx.xxxxx-xxxxxxxxxxxxxxx==/lib/arm64/libUE4.so #46 pc 00000000058de1ac /data/app/~~xxx_xxxxxxxxxxx==/com.xxxxxxx.xxxx.xxxxx-xxxxxxxxxxxxxxx==/lib/arm64/libUE4.so #47 pc 00000000058dde28 /data/app/~~xxx_xxxxxxxxxxx==/com.xxxxxxx.xxxx.xxxxx-xxxxxxxxxxxxxxx==/lib/arm64/libUE4.so #48 pc 00000000058dc814 /data/app/~~xxx_xxxxxxxxxxx==/com.xxxxxxx.xxxx.xxxxx-xxxxxxxxxxxxxxx==/lib/arm64/libUE4.so |
进562cf34这个地方看一下
果然跟之前猜测的差不多，写个frida脚本试试能不能生成类名
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 | function getName(index){ var f_addr = moduleBase.add(0x562b820); // 将目标函数地址转换为JavaScript函数 var getGnameFunc = new NativeFunction(f_addr, 'uint64', []); // 调用目标函数并传递内存地址作为参数 try{ var gname = getGnameFunc(); console.log(`GName: ${gname}`); // dumpVector(buf); //info(ptr(actor_addr).add(0x130).readPointer().add(0x14c).readU8()&32 != 0); } catch (e){ console.log(e) } var offset_FNameEntry_Info = 0; var Block = index >> 16; var Offset = index & 65535; var FNamePool = gname; // console.log(`FNamePool: ${FNamePool}`); console.log(`Block: ${Block}`); var NamePoolChunk = ptr(FNamePool).add(0x40).add (Block*8).readPointer(); console.log(`NamePoolChunk: ${NamePoolChunk}`); var FNameEntry = NamePoolChunk.add((0x2 * index)&0x1FFFE); console.log(`FNameEntry: ${FNameEntry}`); try { if (offset_FNameEntry_Info !== 0) { var FNameEntryHeader = FNameEntry.readU16(); } else { var FNameEntryHeader = FNameEntry.readU16(); } } catch (e) { // console.log(e); return ""; } console.log(`FNameEntryHeader: ${FNameEntryHeader}`); var str_addr = FNameEntry.add(0x2); console.log(`str_addr: ${str_addr}`); var str_length = FNameEntryHeader >> 6; var wide = FNameEntryHeader & 1; console.log(str_length) if (str_length > 0 && str_length < 250) { var str = str_addr.readUtf8String(str_length); console.log(str) } } |
在登陆界面获取看看world的类名
也是验证成功了。
0x3 小结
这次最开始还是花了点时间，看懂了之后就感觉这个方法还挺简单的，也算是见识了一种修改GName的方式。
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