Canvas is not supported in your browser.
首页 课程 文章
无痕注入 APC注入 线程注入 读写驱动 注入技术 句柄表 进程线程 系统调用 保护模式 内存管理 远程CALL 软件调试 驱动封装 云下发 驱动开发 FPS数据 方框透视 FPS方框 FPS自瞄 CE D3DHOOK D3D绘制 Imgui绘制 DWM
内核课程 驱动出租 学习路线 聊天室 免责声明 提问技巧

CTF对抗-KCTF2022秋季赛 第八题 商贸往来 题解

推荐 原创

周杰伦

文章分类 Android安全 CTF对抗 IOS安全 阅读数 : 494 阅读时长 : 9分钟

开头包装的一层调用可以手动清理出来，他调用了sub_4026D2作为窗口回调，在WM_COMMAND里面

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
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
v21 = ( * ( int (__stdcall * * )( int , int ))(dword_4ABE44 + 92 ))(a1, 1001 ); / / GetDlgItem
     if ( v21 )
     {
       for ( i = 0 ; i < 0x100 ; + + i )
         v7[i] = 0 ;
       v42 = ( * ( int (__stdcall * * )( int ))(v35 + 96 ))(v21); / / GetWindowTextLengthA
       if ( v42 < = 210 && v42 > = 1 )
       {
         ( * (void (__stdcall * * )( int , char * , int ))(v35 + 100 ))(v21, v7, 255 ); / / GetWindowTextA
         v42 = ( * ( int (__stdcall * * )(char * ))(v35 + 24 ))(v7); / / lstrlenA
         if ( v42 > = 1 && v42 < = 128 )
         {
           for ( j = v42; j < 128 ; + + j )
           {
             if ( j % 2 )
               v7[j] = 0x20 ;
             else
               v7[j] = 0x7F ;
           }
           v34 = 1 ;
         }
         else
         {
           v34 = 0 ;
         }
       }
       else
       {
         v34 = 0 ;
       }
     }
     else
     {
       v34 = 0 ;
     }
     if ( v34 )
     {
       v43 = dword_4ABE44;
       if ( ( * ( int (__stdcall * * )(_DWORD, char * , int ))(dword_4ABE44 + 56 ))( 0 , v5, 255 ) )
       {
         strcpy(v27, "h" );
         v27[ 2 ] = 0 ;
         v27[ 3 ] = 0 ;
         v27[ 4 ] = 0 ;
         v27[ 5 ] = 0xB8 ;
         v27[ 6 ] = 0 ;
         v27[ 7 ] = 0 ;
         v27[ 8 ] = 0 ;
         v27[ 9 ] = 0 ;
         v27[ 10 ] = 0xFF ;
         v27[ 11 ] = 0xD0 ;
         Eax = 0 ;
         v31 = 0 ;
         v8[ 17 ] = 0xFFFFFFFF ;
         for ( k = 0 ; k < 0x44 ; + + k )
           * ((_BYTE * )v8 + k) = 0 ;
         v8[ 0 ] = 68 ;
         for ( m = 0 ; m < 0x10 ; + + m )
           * ((_BYTE * )&v37 + m) = 0 ;
         if ( ( * ( int (__stdcall * * )(char * , _DWORD, _DWORD, _DWORD, _DWORD, int , _DWORD, _DWORD, int * , int * ))(v43 + 28 ))( / / CreateProcessW
                v5,
                0 ,
                0 ,
                0 ,
                0 ,
                4 ,
                0 ,
                0 ,
                v8,
                &v37) )
         {
           v6.ContextFlags = 0x10007 ;
           if ( !( * ( int (__stdcall * * )( int , CONTEXT * ))(v43 + 32 ))(v38, &v6) ) / / GetThreadContext
             goto LABEL_69;
           Eax = v6.Eax;
           v31 = ( * ( int (__stdcall * * )( int , _DWORD, int , int , int ))(v43 + 44 ))(v37, 0 , 128 , 4096 , 4 );
           if ( !v31 )
             goto LABEL_69;
           for ( n = 0 ; n < 0x80 ; n + = v17 )
           {
             v17 = 0 ;
             if ( !( * ( int (__stdcall * * )( int , unsigned int , char * , unsigned int , int * ))(v43
                                                                                        + 0x30 ))( / / WriteProcessMemory
                     v37,
                     n + v31,
                     &v7[n],
                     128 - n,
                     &v17) )
             {
               v16 = 0 ;
               goto LABEL_45;
             }
           }
           v16 = 1 ;
           if ( !v16 )
             goto LABEL_69;
LABEL_45:
           v20 = (PIMAGE_DOS_HEADER)( * ( int (__stdcall * * )(_DWORD))(v43 + 20 ))( 0 ); / / GetModuleHandleW
           v10 = ( int )v20 + v20 - >e_lfanew;
           v9 = Eax - * (_DWORD * )(v10 + 40 );
           v11 = (char * )sub_401000 - (char * )v20;
           * (_DWORD * )&v27[ 1 ] = v31;
           * (_DWORD * )&v27[ 6 ] = (char * )sub_401000 - (char * )v20 + v9;
           for ( ii = 0 ; ii < 0xC ; ii + = v15 )
           {
             v15 = 0 ;
             if ( !( * ( int (__stdcall * * )( int , unsigned int , char * , unsigned int , int * ))(v43 + 48 ))(
                     v37,
                     ii + Eax,
                     &v27[ii],
                     12 - ii,
                     &v15) )
             {
               v14 = 0 ;
               goto LABEL_52;
             }
           }
           v14 = 1 ;
LABEL_52:
           if ( v14 )
           {
             ( * (void (__stdcall * * )( int ))(v43 + 36 ))(v38); / / ResumeThread
             v30 = 2 ;
             if ( ( * ( int (__stdcall * * )( int , int ))(v43 + 60 ))(v37, 30000 ) ) / / WaitForSingleObject
             {
               ( * (void (__stdcall * * )( int , int ))(v43 + 64 ))(v37, 2 ); / / TerminateProcess
             }
             else
             {
               v18 = 0 ;
               if ( ( * ( int (__stdcall * * )( int , int * ))(v43 + 52 ))(v37, &v18) && v18 ! = 2 ) / / GetExitCodeProcess
                 v30 = v18;
             }

会再执行一次crackme，将入口点改为

1
2
3
push input
mov eax, 0x401000
call eax

0x401000通过调用Decompress函数，解压数据

 

类似格式是

1
2
3
4
struct CodeData{
     uint32_t CodeSize;
     uint8_t code[CodeSize];
};

在这里进行调用，v47用于加密，v45用于最后的验证

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
if ( v38 )
   {
     v90 = 0 ;
     v29[ 0 ] = 5 ;
     v29[ 1 ] = 0 ;
     v29[ 2 ] = 4 ;
     v29[ 3 ] = 3 ;
     v29[ 4 ] = 2 ;
     v29[ 5 ] = 1 ;
     for ( ii = 0 ; ii < 6 ; + + ii )
     {
       v32 = v29[ii];
       v92 = 0 ;
       v47 = 0 ;
       for ( jj = 0 ; jj < = v32; + + jj )
       {
         v47 = ( int (__stdcall * )(_DWORD, _DWORD, _DWORD, _DWORD))(v108[ 30 ] + v92 + 4 );
         v46 = * (_DWORD * )(v108[ 30 ] + v92);
         v92 + = v46 + 4 ;
       }
       v90 = v47;
       if ( !v47( * v108, v108[ 1 ], v108[ 2 ], a1) )
         goto LABEL_134;
     }
     v56 = 1 ;
     v91 = 0 ;
     v45 = 0 ;
     for ( kk = 0 ; kk < = 6 ; + + kk )
     {
       v45 = ( int (__stdcall * )(_DWORD, _DWORD, _DWORD, _DWORD))(v108[ 30 ] + v91 + 4 );
       v48 = * (_DWORD * )(v108[ 30 ] + v91);
       v91 + = v48 + 4 ;
     }
     v90 = v45;
     if ( !v45( * v108, v108[ 1 ], v108[ 2 ], a1) )
       v56 = 0 ;
   }

通过强制F5了几个函数发现，对应输入只进行了基于字节的异或加密、交换、查表，修改其中一个字节，只会对加密结果产生一个字节的影响。

 

这些代码花式调用了大量API，拖慢了计算速度，同时也有反调试。

 

其实根据附带的题目描述我感觉是叫你硬看，但我就偏要硬爆

 

将最后一个函数F5找到比对逻辑，将其导出。

 

将原始文件patch 入口点，push 0x402d4c call 0x401000 后 跟一个int3，然后nop掉0x04026C8的ExitProcess，到达int3后读取和重写flag的值，然后更改Eip为入口点进行下次爆破。

 

需要用到ScyllaHide，爆的时候执行一下InjectorCLIx86.exe sb.exe HookLibraryx86.dll nowait加载一下反反调试，配置文件选Themida x86/x64。

 

预计时间是(128 + 94) * 10 / 60 = 37分钟，

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
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
#include <windows.h>
#include <TlHelp32.h>
#include <stdint.h>
#include <stdio.h>
 
char trueflag[ 0x81 ] = { 0 };
/ / char flag[ 0x81 ] = { 0x3a , 0x2a , 0x44 , 0x23 , 0x4f , 0x2b , 0x5f , 0x49 , 0x33 , 0x3b , 0x60 , 0x7d , 0x30 , 0x4e , 0x66 , 0x50 ,
/ / 0x2d , 0x3d , 0x32 , 0x2f , 0x2b , 0x59 , 0x22 , 0x5f , 0x3e , 0x41 , 0x38 , 0x53 , 0x36 , 0x5d , 0x4c , 0x7c ,
/ / 0x34 , 0x47 , 0x3b , 0x55 , 0x48 , 0x69 , 0x41 , 0x35 , 0x6d , 0x6e , 0x6f , 0x6c , 0x5e , 0x6b , 0x3b , 0x23 ,
/ / 0x4f , 0x68 , 0x57 , 0x32 , 0x21 , 0x55 , 0x45 , 0x4a , 0x66 , 0x30 , 0x22 , 0x37 , 0x3f , 0x44 , 0x74 , 0x35 ,
/ / 0x6d , 0x7b , 0x43 , 0x71 , 0x45 , 0x2a , 0x41 , 0x5a , 0x72 , 0x7e , 0x24 , 0x31 , 0x28 , 0x7a , 0x57 , 0x40 ,
/ / 0x54 , 0x42 , 0x58 , 0x4b , 0x4c , 0x26 , 0x32 , 0x72 , 0x3f , 0x2b , 0x33 , 0x6b , 0x77 , 0x78 , 0x43 , 0x39 ,
/ / 0x30 , 0x4f , 0x27 , 0x25 , 0x26 , 0x50 , 0x79 , 0x56 , 0x6f , 0x7e , 0x29 , 0x27 , 0x51 , 0x25 , 0x5a , 0x40 ,
/ / 0x36 , 0x62 , 0x7d , 0x52 , 0x45 , 0x4b , 0x46 , 0x5b , 0x63 , 0x67 , 0x46 , 0x65 , 0x2f , 0x2d , 0x3f , 0x49 };
char flag[ 0x81 ] = { 0 };
 
int flagcount = 0 ;
int _current = 0 ;
uint8_t encrelative[ 0x80 ] = { 0 };
uint8_t enctable[ 0x80 ] = { 0 };
/ / uint8_t enctable[ 0x80 ] = { 0x09 , 0x0a , 0x07 , 0x08 , 0x05 , 0x06 , 0x03 , 0x04 , 0x01 , 0x02 , 0x40 , 0x00 , 0x42 , 0x41 , 0x44 , 0x43 ,
/ / 0x46 , 0x45 , 0x48 , 0x47 , 0x4a , 0x49 , 0x4c , 0x4b , 0x4e , 0x4d , 0x50 , 0x4f , 0x52 , 0x51 , 0x54 , 0x53 ,
/ / 0x56 , 0x55 , 0x58 , 0x57 , 0x5a , 0x59 , 0x5c , 0x5b , 0x5e , 0x5d , 0x60 , 0x5f , 0x62 , 0x61 , 0x64 , 0x63 ,
/ / 0x66 , 0x65 , 0x68 , 0x67 , 0x6a , 0x69 , 0x6c , 0x6b , 0x6e , 0x6d , 0x70 , 0x6f , 0x72 , 0x71 , 0x74 , 0x73 ,
/ / 0x76 , 0x75 , 0x78 , 0x77 , 0x7a , 0x79 , 0x7c , 0x7b , 0x7e , 0x7d , 0x3f , 0x7f , 0x3d , 0x3e , 0x3b , 0x3c ,
/ / 0x39 , 0x3a , 0x37 , 0x38 , 0x35 , 0x36 , 0x33 , 0x34 , 0x31 , 0x32 , 0x2f , 0x30 , 0x2d , 0x2e , 0x2b , 0x2c ,
/ / 0x29 , 0x2a , 0x27 , 0x28 , 0x25 , 0x26 , 0x23 , 0x24 , 0x21 , 0x22 , 0x1f , 0x20 , 0x1d , 0x1e , 0x1b , 0x1c ,
/ / 0x19 , 0x1a , 0x17 , 0x18 , 0x15 , 0x16 , 0x13 , 0x14 , 0x11 , 0x12 , 0x0f , 0x10 , 0x0d , 0x0e , 0x0b , 0x0c };
int stage = 1 ;
int guess = 33 ;
uint8_t enc[ 0x80 ] = { 121 , 23 , 66 , 107 , 59 , 80 , 122 , 227 , 70 , 208 , 222 , 78 , 36 , 167 , 138 , 106 , 105 , 208 , 2 , 6 , 240 , 39 , 36 , 189 , 192 , 187 , 227 , 30 , 9 , 163 , 151 , 48 , 60 , 182 , 235 , 104 , 144 , 9 , 208 , 234 , 17 , 242 , 196 , 96 , 165 , 203 , 195 , 252 , 69 , 251 , 92 , 83 , 192 , 128 , 58 , 153 , 89 , 111 , 47 , 84 , 74 , 217 , 14 , 106 , 52 , 222 , 210 , 236 , 175 , 74 , 11 , 164 , 138 , 182 , 250 , 147 , 31 , 4 , 16 , 68 , 238 , 228 , 214 , 158 , 244 , 69 , 18 , 77 , 55 , 60 , 240 , 17 , 248 , 200 , 68 , 118 , 99 , 16 , 115 , 45 , 104 , 215 , 157 , 47 , 195 , 132 , 42 , 182 , 204 , 181 , 55 , 97 , 79 , 15 , 22 , 188 , 187 , 140 , 83 , 39 , 238 , 119 , 170 , 31 , 156 , 194 , 24 , 222 };
uint8_t tmp[ 0x80 ] = { 0 };
 
 
 
int main(void) {
     STARTUPINFOA si = { sizeof(si) };
     PROCESS_INFORMATION pi = { sizeof(pi) };
     DWORD ret = CreateProcessA( "D:/Users/CShi/Desktop/sb.exe" , "", NULL, NULL, FALSE, DEBUG_PROCESS | CREATE_SUSPENDED, NULL, NULL, &si, &pi);
     DWORD __sb = 0 ;
     uint8_t original = 0 ;
     uint8_t int3 = 0xcc ;
 
     ReadProcessMemory(pi.hProcess, 0x004041B5 , &original, 1 , &__sb);
 
     WriteProcessMemory(pi.hProcess, 0x004041B5 , &int3, 1 , &__sb);
     ResumeThread(pi.hThread);
     DEBUG_EVENT de = { 0 };
     CONTEXT ThreadContext = { 0 };
     ThreadContext.ContextFlags = 0x10007 ;
     while ( 1 ){
         WaitForDebugEvent(&de, INFINITE);
         if (de.dwDebugEventCode = = EXCEPTION_DEBUG_EVENT){
             if (de.u.Exception.ExceptionRecord.ExceptionCode = = 0x80000003 ){
                 if (de.u.Exception.ExceptionRecord.ExceptionAddress = = (LPVOID) 0x004041B5 ){
 
                     puts( "InjectorCLIx86.exe sb.exe HookLibraryx86.dll nowait" );
                     system( "pause" );
 
                     WriteProcessMemory(pi.hProcess, 0x4041b5 , &original, 1 , &__sb);
 
                     HANDLE hThread = OpenThread(THREAD_ALL_ACCESS, FALSE, de.dwThreadId);
                     GetThreadContext(hThread, &ThreadContext);
                     WriteProcessMemory(pi.hProcess, 0x402d4c , &flag, 0x80 , &__sb);
                     ThreadContext.Eip = 0x4041b5 ;
                     SetThreadContext(hThread, &ThreadContext);
                     CloseHandle(hThread);
                 }
                 else if (de.u.Exception.ExceptionRecord.ExceptionAddress = = (LPVOID) 0x04041BF ){
                     if (stage = = 1 ){
                         if (encrelative[ 0 ] = = 0 ){
                             ReadProcessMemory(pi.hProcess, 0x402d4c , &encrelative, 0x80 , &__sb);
                         }
                         else {
                             ReadProcessMemory(pi.hProcess, 0x402d4c , &tmp, 0x80 , &__sb);
                             for ( int i = 0 ;i< 0x80 ;i + + ){
                                 if (tmp[i] ! = encrelative[i]){
                                     enctable[_current - 1 ] = i;
                                     break ;
                                 }
                             }
                         }
                         memset(flag, 0 , sizeof(flag));
                         if (_current = = 0x81 ) {
                             memset(flag, 0 , sizeof(flag));
                             stage = 2 ;
                             _current = 0 ;
                             flag[_current] = guess;
                         }
                         else {
                             flag[_current] = 1 ;
                             _current + = 1 ;
                         }
                         puts( "enctable debug:" );
                         for ( int i = 0 ; i < 128 ; i + + ) {
 
                             printf( "0x%02x," , enctable[i]);
                             if (i % 16 = = 15 ) {
                                 puts("");
                             }
                         }
 
                     }
                     else {
                         ReadProcessMemory(pi.hProcess, 0x402d4c , &tmp, 0x80 , &__sb);
                         for ( int i = 0 ;i< 0x80 ;i + + ){
                             if (tmp[i] = = enc[i]) {
                                 for ( int j = 0 ; j < 0x80 ; j + + ) {
                                     if (enctable[j] = = i){
                                         printf( "%x: %c OK!\n" , j, flag[j]);
                                         flagcount + = 1 ;
                                         trueflag[j] = flag[j];
                                         if (flagcount = = 0x80 ) {
                                             printf( "%s\n" , trueflag);
                                             system( "pause" );
                                         }
                                         break ;
                                     }
 
                                 }
                             }
                         }
 
                         puts("");
                         memset(flag, guess, 128 );
 
                         guess + = 1 ;
                         printf( "%x: %c current\n" , _current, flag[_current]);
                         puts( "flag debug:" );
                         for ( int i = 0 ; i < 128 ; i + + ) {
                             printf( "0x%02x," , trueflag[i]);
                             if (i % 16 = = 15 ) {
                                 puts("");
                             }
                         }
                         if (guess = = 128 ) {
                             puts( "No Solve!" );
                         }
                     }
 
                     HANDLE hThread = OpenThread(THREAD_ALL_ACCESS, FALSE, de.dwThreadId);
                     GetThreadContext(hThread, &ThreadContext);
                     WriteProcessMemory(pi.hProcess, 0x402d4c , &flag, 0x80 , &__sb);
                     ThreadContext.Eip = 0x4041b5 ;
                     SetThreadContext(hThread, &ThreadContext);
                     CloseHandle(hThread);
 
                 }
 
             }
             ContinueDebugEvent(de.dwProcessId, de.dwThreadId, DBG_CONTINUE);
 
         }
 
 
         else {
 
             ContinueDebugEvent(de.dwProcessId, de.dwThreadId, DBG_CONTINUE);
 
         }
 
     }
 
 
 
 
 
}


更多【KCTF2022秋季赛 第八题 商贸往来 题解】相关视频教程：www.yxfzedu.com




相关文章推荐

记录自己的技术轨迹
文章规则：
1)：文章标题请尽量与文章内容相符
2)：严禁色情、血腥、暴力
3)：严禁发布任何形式的广告贴
4)：严禁发表关于中国的政治类话题
5)：严格遵守中国互联网法律法规
6)：有侵权,疑问可发邮件至service@yxfzedu.com
近期原创 更多
友情链接
内核结构 FAQ
免责声明
课程目录
Windows内核
游戏逆向(FPS)
技术交流QQ群
342478842 215039827 137189196
314055665 159620936
微信公众号
www.yxfzedu.com是一个分享游戏安全,游戏外挂与反外挂,游戏驱动保护的视频网站！
接各种驱动定制如：游戏读写驱动，软件内存保护，防止调试等功能定制。
出租读写驱动，调试驱动，无痕注入支持各种游戏。
邮箱：service@yxfzedu.com
QQ：851920120
特别说明：不接游戏数据分析，外挂编写，登陆协议等类似业务。