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[原创]TikTok越狱检测之一 <代码模块污染检测>
发表于: 2024-3-16 16:58 6822

[原创]TikTok越狱检测之一 <代码模块污染检测>

2024-3-16 16:58
6822

话说某天在国外论坛闲逛,有一国外小哥,发帖交流TikTok 的相关越狱检测,对TikTok的安全保护极其变态。
好奇心驱使之下,便下载TikTok,注册完账号,竟然什么都做不了,只能浏览视频。
基于逆向的本能,越狱手机应该被检测出来了。
于是便开始了分析该软件。
果然,TikTok的保护极其完善,很多保护都是笔者之前没有接触过的。
把检测的一些函数逆向出来,以后正向开发也有参考价值。
新加坡singpass 政务app也有该相关检测方法
特此记录.

1.<代码模块污染检测>
原理:TikTok加载的内存模块和官方的缓存模块

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const char *sharedCachePaths[] = {    "/System/Library/Caches/com.apple.dyld/dyld_shared_cache_arm64",      "/System/Library/Caches/com.apple.dyld/dyld_shared_cache_arm64e",
"/System/Library/dyld/dyld_shared_cache_arm64e"
};

进行比较,不一致就说明了TikTok加载的内存模块被篡改了,函数被Hook,或者代码被patch

//根据checkAddress判断该地址所在内存加载模块和 "/System/Library/Caches/com.apple.dyld/dyld_shared_cache_arm64" 官方模块比较
//是否已经被修改过,模块被修改过,返回true,模块没有被修改过返回false

  1. 调用dladdr函数 获取待检测checkAddress内存地址所在的模块
  2. 获取模块名称checkfname,模块代码地址checkTextCommand,模块大小 checkTextVmSize
  3. 映射官方的缓存模块 sharedCachePaths
  4. 从官方的缓存模块中匹配到checkfname模块
  5. 获取匹配模块,代码地址 matchTextCommand
  6. 对待检测的checkTextCommand 和 已经匹配的matchTextCommand进行逐字节比较,一致则说明没有被修改过,不一致则说明被污染了

+(bool)IsRiskModule:(uint64_t)checkAddress {

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Dl_info checkDlinfo;
if(!dladdr((const void *)checkAddress, &checkDlinfo)){
    return false;
}
const char * checkfname = checkDlinfo.dli_fname;
struct mach_header_64 * checkMachHeader  = (struct mach_header_64 *) checkDlinfo.dli_fbase;
if (checkMachHeader->magic != MH_MAGIC_64)
    return false;
if(checkMachHeader->ncmds == 0)
    return false;
struct segment_command_64 * checkCommand  = (struct segment_command_64 *) ((char *)checkMachHeader + sizeof(struct mach_header_64));
struct segment_command_64 * checkTextCommand  = NULL;
for (int i =0; i< checkMachHeader->ncmds; i++) {
    if ((checkCommand->cmd == LC_SEGMENT_64)   && (strcmp(checkCommand->segname, "__TEXT") == 0))
    {
        checkTextCommand = checkCommand;
        break;
    }
    checkCommand =(struct segment_command_64 *) ((uint64_t)checkCommand + checkCommand->cmdsize);
}
if (!checkTextCommand)
    return false;
uint64_t checkTextVmSize = checkTextCommand->vmsize;
 
 
kern_return_t kernReturn = KERN_SUCCESS;
const char *sharedCachePaths[] = {
    "/System/Library/Caches/com.apple.dyld/dyld_shared_cache_arm64",
    "/System/Library/Caches/com.apple.dyld/dyld_shared_cache_arm64e",
    "/System/Library/dyld/dyld_shared_cache_arm64e",
};
int fd = -1;
for (int i = 0;i < sizeof(sharedCachePaths) / sizeof(char *);i++) {
    fd = open(sharedCachePaths[i], O_RDONLY);
    if (fd != -1) {
        break;
    }
}
if (fd == -1)
    return false;
 
vm_size_t vmPageSize = vm_page_size;
unsigned char* p_map =( unsigned char*) mmap(0, vmPageSize, PROT_READ,MAP_NOCACHE|MAP_PRIVATE, fd, 0);
if (p_map == MAP_FAILED) {
    //映射失败
    close(fd);
    return false;
}
 
struct dyld_cache_header * cacheHeader = ( struct dyld_cache_header *)p_map;
if(strcmp(cacheHeader->magic, "dyld_v1   arm64") != 0){
    munmap(p_map, vmPageSize);
    close(fd);
    return false;
}
struct dyld_cache_mapping_info* mappings = (struct dyld_cache_mapping_info*)(cacheHeader->mappingOffset + (uintptr_t)cacheHeader);
uintptr_t length =  mappings[0].size;
munmap(p_map, vmPageSize);
 
vmPageSize = length;
p_map =( unsigned char *) mmap(0, vmPageSize, PROT_READ, MAP_NOCACHE|MAP_PRIVATE|MAP_NORESERVE, fd, 0);
if (p_map == MAP_FAILED) {
    //映射失败
    printf("error:%s\n", strerror(errno));
    close(fd);
    return false;
}
 
cacheHeader = ( struct dyld_cache_header *)p_map;
mappings = (struct dyld_cache_mapping_info*)(cacheHeader->mappingOffset + (uintptr_t)cacheHeader);
//非越狱系统 imagesCount = 0  越狱系统 imagesCount > 0
uint32_t imagesCount = cacheHeader->imagesCount;
if (imagesCount == 0) {
    munmap(p_map, vmPageSize);
    close(fd);
    return false;
}
 
 
struct dyld_cache_image_info* dylibs = (struct dyld_cache_image_info*)((uintptr_t)cacheHeader + cacheHeader->imagesOffset);
struct dyld_cache_image_info * matchDylib = NULL;
for (uint32_t i=0; i < imagesCount; i++) {
    const char* dylibPath  = (char*)cacheHeader + dylibs[i].pathFileOffset;
    if (strcmp(checkfname, dylibPath) == 0) {
        matchDylib = (struct dyld_cache_image_info*)&dylibs[i];
        //NSLog(@"IsRiskModule 函数,匹配到 filename =%s",dylibPath);
        break;
    }
}
 
if (!matchDylib) {
    NSLog(@"IsRiskModule 函数,找不到 filename =%s",checkfname);
    munmap(p_map, vmPageSize);
    close(fd);
    return false;
}
uint64_t offset = 0;
bool bMatch = false;
for (int i = 0 ; i< cacheHeader->mappingCount; i++) {
    uint64_t StartAddress =mappings[i].address;
    if (matchDylib->address >= StartAddress){
        uint64_t EndAddress = mappings[i].address +mappings[i].size;
        if (matchDylib->address <= EndAddress) {
            offset =  matchDylib->address - mappings[i].address + mappings[i].fileOffset ;
            bMatch = true;
            break;;
        }
    }
}
if (!bMatch) {
    munmap(p_map, vmPageSize);
    close(fd);
    return false;
}
struct mach_header_64* matchHeader = (struct mach_header_64*)((uintptr_t)cacheHeader + offset);
if(matchHeader->ncmds == 0)
    return false;
struct segment_command_64 * matchCommand  = (struct segment_command_64 *) ((char *)matchHeader + sizeof(struct mach_header_64));
struct segment_command_64 * matchTextCommand  = NULL;
for (int i =0; i< matchHeader->ncmds; i++) {
    if ((matchCommand->cmd == LC_SEGMENT_64)   && (strcmp(matchCommand->segname, "__TEXT") == 0))
    {
        matchTextCommand = matchCommand;
        break;
    }
 
matchCommand =(struct segment_command_64 *) ((uint64_t)matchCommand + matchCommand->cmdsize);
}
if (!matchTextCommand) {
    munmap(p_map, vmPageSize);
    close(fd);
    return false;
}
 
if (matchTextCommand->vmsize != checkTextVmSize ) {
    munmap(p_map, vmPageSize);
    close(fd);
    return true;
}
bool bIsRisk = false;
for (int i = 0; i< checkTextVmSize ; i++) {
    unsigned char Byte1 = *(unsigned char*) ((uint64_t)matchHeader+i);
    unsigned char Byte2 = *(unsigned char*) ((uint64_t)checkMachHeader+i);
    if (Byte1 != Byte2)
    {
        bIsRisk = true;
        NSLog(@"IsRiskModule 被污染的库,filename =%s,基地址 = 0x%llX,函数地址=0x%llX",checkfname,((uint64_t)checkMachHeader),(uint64_t)i);
        break;
    }
}
munmap(p_map, vmPageSize);
close(fd);
return bIsRisk;

}


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好奇国外小哥的 原始帖子
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偶然发现的
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请问是哪个版本的TT
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哈哈,从TT还原度为98%,可以一起研究研究,提高自己app 的安全性。Q:1793260563
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