分析目标
下面分析的主要是少年三国志。
Lua脚本解密与DUMP
LuaJitIDA分析调用树：
- AppDelegate::applicationDidFinishLaunching(AppDelegate *__hidden this) EXPORT _ZN11AppDelegate29applicationDidFinishLaunchingEv
- cocos2d::CCLuaEngine::defaultEngine(cocos2d::CCLuaEngine *__hidden this) EXPORT _ZN7cocos2d11CCLuaEngine13defaultEngineEv
- cocos2d::CCLuaEngine::init(cocos2d::CCLuaEngine *__hidden this) EXPORT _ZN7cocos2d11CCLuaEngine4initEv
- cocos2d::CCLuaStack::create(cocos2d::CCLuaStack *__hidden this) EXPORT _ZN7cocos2d10CCLuaStack6createEv
- cocos2d::CCLuaStack::init(cocos2d::CCLuaStack *__hidden this) EXPORT _ZN7cocos2d10CCLuaStack4initEv
- cocos2dx_lua_loader
- cocos2d::CCLuaStack::lua_loadbuffer(lua_State , char const, int, char const) EXPORT *ZN7cocos2d10CCLuaStack14lua_loadbufferEP9lua_StatePKciS4
cocos2d::CCLuaStack::lua_loadbuffer先调用以下函数解密： cocos2d::extra::CCCrypto::decryptUF(uchar ,int,int *,int *) EXPORT *ZN7cocos2d5extra8CCCrypto9decryptUFEPhiPiS3 最后再调用：luaL_loadbuffer
因此可以直接对luaL_loadbuffer进行HOOK，进而DUMP出Lua脚本，网上搜索函数声明：
int luaL_loadbuffer (lua_State *L, const char *buff, size_t sz, const char *name);
进而实现HOOK代码：
//orig function copy
int (*luaL_loadbuffer_orig)(void *L, const char *buff, int size, const char *name) = NULL;
//local function
int luaL_loadbuffer_mod(void *L, const char *buff, int size, const char *name) {
LOGD("[dumplua] luaL_loadbuffer name: %s lua: %s", name, buff);
return luaL_loadbuffer_orig(L, buff, size, name);
}
void hook() {
LOGD("[dumplua] hook begin");
void *handle = dlopen("libgame.so", RTLD_NOW);
if (handle == NULL) {
LOGE("[dumplua]dlopen err: %s.", dlerror());
return;
}else{
LOGD("[dumplua] libgame.so dlopen OK!");
}
void *pluaL_loadbuffer = dlsym(handle, "luaL_loadbuffer");
if (pluaL_loadbuffer == NULL){
LOGE("[dumplua] lua_loadbuffer not found!");
LOGE("[dumplua] dlsym err: %s.", dlerror());
}else{
LOGD("[dumplua] luaL_loadbuffer found!");
MSHookFunction(pluaL_loadbuffer, (void *)&luaL_loadbuffer_mod, (void **)&luaL_loadbuffer_orig);
}
}
运行后拦截到的输出信息：
01-05 19:29:27.674 13191-13215/? D/SUBSTRATEHOOK: [dumplua] luaL_loadbuffer name: assets/scripts/main.lua lua:
function __G__TRACKBACK__(errorMessage)
print("----------------------------------------")
print("LUA ERROR: " .. tostring(errorMessage) .. "\n")
local traceback = debug.traceback("", 2)
print(traceback)
print("----------------------------------------")
--只有G_Report初始过后才会对错误日志做处理
if G_Report ~= nil then
G_Report:onTrackBack(errorMessage, traceback)
end
if SHOW_EXCEPTION_TIP and uf_notifyLayer ~= nil then
uf_notifyLayer:getDebugNode():removeChildByTag(10000)
local text = tostring(errorMessage)
require("upgrade.ErrMsgBox").showErrorMsgBox(text)
end
end
function traceMem(desc)
if desc == nil then
desc = "memory:"
end
if CCLuaObjcBridge then
local callStaticMethod = CCLuaObjcBridge.callStaticMethod
local ok, ret = callStaticMethod("NativeProxy", "getUsedMemory", nil)
if ok then
pri
01-05 19:29:27.679 13191-13215/? D/SUBSTRATEHOOK: [dumplua] luaL_loadbuffer name: upgrade.AntiAddictionLayer lua: LJ-
01-05 19:29:27.679 13191-13215/? D/SUBSTRATEHOOK: [dumplua] luaL_loadbuffer name: upgrade.ComSdkUtils lua: LJA
01-05 19:29:27.684 13191-13215/? D/SUBSTRATEHOOK: [dumplua] luaL_loadbuffer name: upgrade.config lua: LJ?
01-05 19:29:27.684 13191-13215/? D/SUBSTRATEHOOK: [dumplua] luaL_loadbuffer name: upgrade.ConfigLayer lua: LJ]
01-05 19:29:27.684 13191-13215/? D/SUBSTRATEHOOK: [dumplua] luaL_loadbuffer name: upgrade.EffectNode_Upgrade lua: LJ?
01-05 19:29:27.684 13191-13215/? D/SUBSTRATEHOOK: [dumplua] luaL_loadbuffer name: upgrade.ErrMsgBox lua: LJP
01-05 19:29:27.684 13191-13215/? D/SUBSTRATEHOOK: [dumplua] luaL_loadbuffer name: upgrade.game lua: LJ?
01-05 19:29:27.684 13191-13215/? D/SUBSTRATEHOOK: [dumplua] luaL_loadbuffer name: upgrade.NativeCallUtils lua: LJ?
01-05 19:29:27.684 13191-13215/? D/SUBSTRATEHOOK: [dumplua] luaL_loadbuffer name: upgrade.NativeProxy lua: LJ?
01-05 19:29:27.684 13191-13215/? D/SUBSTRATEHOOK: [dumplua] luaL_loadbuffer name: upgrade.Patcher lua: LJ?
01-05 19:29:27.689 13191-13215/? D/SUBSTRATEHOOK: [dumplua] luaL_loadbuffer name: upgrade.SplashLayer lua: LJ-
01-05 19:29:27.689 13191-13215/? D/SUBSTRATEHOOK: [dumplua] luaL_loadbuffer name: upgrade.upgrade lua: LJ6
可见，有些Lua脚本是源码形式，有些是LuaJit编译的，可以改写以上代码把脚本DUMP到文件中再进一步分析，此处略。
资源解密与DUMP
主要函数： cocos2d::CCImage::initWithImageFile调用 cocos2d::CCImage::initWithImageData
但是IDA分析发现initWithImageData会调用cocos2d::extra::CCCrypto::decryptXXTEA和cocos2d::extra::CCCrypto::decryptUF进行解密，最后再加载图片资源。以下是initWithImageData部分代码：
if ( s )
{
v12 = (unsigned __int8 *)strlen(s);
v13 = (void *)cocos2d::extra::CCCrypto::decryptXXTEA(v9, v11, (int)s, v12, (int)v24, v22);
v14 = v13;
if ( v13 )
v9 = (cocos2d::extra::CCCrypto *)v13;
goto LABEL_28;
}
v14 = 0;
if ( (signed int)a3 > 3 && *(_BYTE *)this == 85 && *((_BYTE *)this + 1) == 70 )
{
v25 = 0;
cocos2d::extra::CCCrypto::decryptUF(this, (int)a3, (int)&v25, v24, v21);
v15 = v25 >> 4;
if ( (v25 & 0xFu) <= 9 )
*(_DWORD *)(v8 + 36) = v25 & 0xF;
switch ( v15 )
{
case 1:
v16 = 1067030938;
break;
case 2:
v16 = 1068708659;
也即会调用cocos2d::extra::CCCrypto::decryptXXTEA和cocos2d::extra::CCCrypto::decryptUF进行解密操作。我们看下cocos2d::extra::CCCrypto::decryptUF这个函数，通过IDA的F5插件，并不断修改变量名可以获得一个比较清晰的C代码。
int __fastcall cocos2d::extra::CCCrypto::decryptUF(cocos2d::extra::CCCrypto *pInBuff, int nlen, int a3, int *pOutLen, int *name)
{
cocos2d::extra::CCCrypto *pInBuff2; // r5@1
int *pOutLen2; // r7@1
int v7; // r3@4
int v8; // r6@5
int v9; // r1@6
int result; // r0@9
int v11; // r4@10
int v12; // r6@12
int v13; // r6@15
signed int v14; // r0@19
int v15; // [sp+0h] [bp-28h]@5
int v16; // [sp+0h] [bp-28h]@10
int v17; // [sp+4h] [bp-24h]@5
pInBuff2 = pInBuff;
pOutLen2 = pOutLen;
if ( nlen <= 3 )
{
v14 = 1;
return -v14;
}
if ( *(_BYTE *)pInBuff != 'U' || *((_BYTE *)pInBuff + 1) != 'F' )
{
v14 = 2;
return -v14;
}
*(_DWORD *)a3 = *((_BYTE *)pInBuff + 2);
v7 = *((_BYTE *)pInBuff + 3);
if ( v7 == 1 )
{
v15 = nlen - 5;
v17 = *((_BYTE *)pInBuff + 4);
v8 = 0;
while ( v8 < v15 )
{
v9 = (v8++ + v17) % 0x21;
*(_BYTE *)pInBuff2 = *((_BYTE *)pInBuff2 + 5) ^ byte_6D192C[v9];
pInBuff2 = (cocos2d::extra::CCCrypto *)((char *)pInBuff2 + 1);
}
*pOutLen2 = v15;
}
else
{
result = 0;
if ( v7 != 2 )
return result;
v11 = 0;
v16 = *((_BYTE *)pInBuff2 + 4);
do
{
*((_BYTE *)pInBuff2 + v11) = *((_BYTE *)pInBuff2 + nlen + v11 - 5) ^ byte_6D192C[(v11 + v16) % 33 + 33];
++v11;
}
while ( v11 != 5 );
v12 = nlen - 10;
if ( nlen - 10 > 95 )
v12 = 95;
v13 = v12 + 4;
while ( v13 >= v11 )
{
*((_BYTE *)pInBuff2 + v11) ^= byte_6D192C[(v11 + v16) % 33 + 33];
++v11;
}
*pOutLen2 = nlen - 5;
}
return 0;
}
其实看到这里应该也是比较容易逆向分析出解密的算法的，应该说比较简单，可以直接写一个脚本来解密assets里的资源。但是为了保证通用性，还是写HOOK代码比较好。
本来分析以为最终都会调用_initWithWebpData、_initWithJpgData、_initWithBpgData、_initWithPngData、_initWithTiffData、_initWithRawData这些函数的，但是实际上分别HOOK后并没有被拦截，所以最后还是HOOK了下cocos2d::extra::CCCrypto::decryptUF。
static string g_strDataPath;
static int g_nCount = 1;
string getNextFilePath(const char *fileExt) {
char buff[100] = {0};
++g_nCount;
sprintf(buff, "%s/cache/%d%s", g_strDataPath.c_str(), g_nCount, fileExt);
return buff;
}
bool saveFile(const void* addr, int len, const char *outFileName)
{
bool bSuccess = false;
FILE* file = fopen(outFileName, "wb+");
if (file != NULL) {
fwrite(addr, len, 1, file);
fflush(file);
fclose(file);
bSuccess = true;
chmod(outFileName, S_IRWXU | S_IRWXG | S_IRWXO);
}else{
LOGE("[%s] fopen failed, error: %s", __FUNCTION__, dlerror());
}
return bSuccess;
}
//hook decryptUF
int (*decryptUF_orig)(void *pInBuff, int len, int *n, int *poutlen, char *name) = NULL;
int decryptUF_mod(void *pInBuff, int len, int *n, int *poutlen, char *name) {
int ret = decryptUF_orig(pInBuff, len, n, poutlen, name);
saveFile(pInBuff, *poutlen, getNextFilePath(".png").c_str());
return ret;
}
void hook() {
//hook decryptUF
void *decryptUF = dlsym(handle, "_ZN7cocos2d5extra8CCCrypto9decryptUFEPhiPiS3_");
if ( decryptUF==NULL ) {
LOGE("[dumplua] _ZN7cocos2d5extra8CCCrypto9decryptUFEPhiPiS3_ (decryptUF) not found!");
LOGE("[dumplua] dlsym err: %s.", dlerror());
}else{
LOGD("[dumplua] _ZN7cocos2d5extra8CCCrypto9decryptUFEPhiPiS3_ (decryptUF) found!");
MSHookFunction(decryptUF, (void *)&decryptUF_mod, (void **)&decryptUF_orig);
}
}
我这里图方便把所有解密的数据都DUMP为/data/data/packagename/cache目录下扩展名为PNG的文件了，最后通过脚本从手机中批量提取出解密后的文件：
#coding:utf-8
import os
for i in range(1, 10000):
cmd = 'adb pull /data/data/com.youzu.android.snsgz/cache/' + str(i) +'.png' + ' e:\\test'
os.system(cmd)
其实通过上面的分析就可以知道，图片资源的解密和Lua的解密都是调用了相同的函数，因此解密出的文件不全是图片，还有写LuaJit的脚本文件，用十六进制编辑器打开就可以看到LJ开头的魔法数字。
全民水浒
全民水浒这个比较简单，资源直接没加密处理，解压缩APK文件就可以在assets目录下查看了。Lua脚本可以通过HOOK函数luaL_loadbuffer获得，而且可以看出只是对编译的Lua脚本做了简单的加密，可以直接DUMP出来，相对少年三国志稍微弱了一些。
01-05 20:04:16.569 17729-17886/? D/SUBSTRATEHOOK: [dumplua] luaL_loadbuffer name: require "UpdateScene.lua" lua: require "UpdateScene.lua"
01-05 20:04:16.574 17729-17886/? D/SUBSTRATEHOOK: [dumplua] luaL_loadbuffer name: UpdateScene.lua lua: LuaQ
01-05 20:04:16.574 17729-17886/? D/SUBSTRATEHOOK: [dumplua] luaL_loadbuffer name: Modal.lua lua: LuaQ
01-05 20:04:16.574 17729-17886/? D/SUBSTRATEHOOK: [dumplua] luaL_loadbuffer name: UIDefine.lua lua: LuaQ
01-05 20:04:16.574 17729-17886/? D/SUBSTRATEHOOK: [dumplua] luaL_loadbuffer name: MessageBox.lua lua: LuaQ
01-05 20:04:16.579 17729-17886/? D/SUBSTRATEHOOK: [dumplua] luaL_loadbuffer name: SoundManager.lua lua: LuaQ
01-05 20:04:16.579 17729-17886/? D/SUBSTRATEHOOK: [dumplua] luaL_loadbuffer name: SoundConfig.lua lua: LuaQ
文档信息
- 本文作者：zhupite
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