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woxihuannisja/vmp3-import-fix

Fix VMProtect3 IAT
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VMProtect 3.x IAT Fix and Rebuild Import Table

This Program is a dynamic x86/x64 VMProtect 3. x import fixer(Tested on VMP3.3). The main goal of this project was to build a correct and reliable tool to fix imports in x86/x64 applications.

Note: This tool can dump and rebuild import directory.

Fix the 32bit program please use the 32bit version, and vice versa.

Before

image-20220716105829428

After

image-20220716105855534

new IAT:

image-20220716110043838

Compile

VS2019

Usage

image-20220723214955839

**-Usage

-p: target process PID

-s:This tool first search call IAT address in sections,-s option specify ignore sections default [.vmp0,.vmp1,.vmp2]

-i: specify the section that is used to store IAT in memory, if you don't specify this option, this tool default will use VirtualAlloc to allocate memory that is used to store IAT content

-d: dump file and rebuild import table

Tips: VMProtect unpacking must be complete before running this tool,

Example:

when The target program reaches OEP

image-20220716111549696

execute this tool

.\vmp3-import-fix.exe -p 31652

if you want to dump and rebuild import table

.\vmp3-import-fix.exe -p 31652 -d

if you want to dump, rebuild import table , and fix the new IAT in .vmp0 section

.\vmp3-import-fix.exe -p 31652 -d -i ".vmp0"

below is the result that has dumped and fixed import table for ida.vmp.exe

image-20220723215541893

new IAT section in the last section

image-20220723215557934

you can see the log file in log/logger.txt

image-20220716111801572

image-20220716111829226

VMProtect Encrypt IAT detail

VMProtect encrypts IAT through 3 modes

  1. call ret or call int3 or call 0xXX
  2. push call
  3. pop call

Call Ret mode

original code:

.text:0040D87E 50                              push   eax       *; hFile*

.text:0040D87F FF 15 1C C1 45 00               call   ds:FlushFileBuffers

.text:0040D885 85 C0                            test   eax, eax

encdrypt IAT

0040D87E | 50                         | push eax                                                   |
0040D87F | E8 47890B00                | call test1_vmp.4C61CB                                      |
0040D884 | C3                         | ret                                                        |
0040D885 | 85C0                       | test eax,eax                                               |

at address 0x0040D87F,code call ds:FlushFileBuffers has changed to call test1_vmp.4C61CB ;ret

we follow encrypt IAT code,below codes analyze the process that VMProtect decrypts API Address

004C61CC | 55                         | push ebp                                                   |保存ebp
004C61CD | 0FCD                       | bswap ebp                                                  |
004C61CF | 66:8BE9                    | mov bp,cx                                                  |
004C61D2 | 66:BD F53D                 | mov bp,3DF5                                                |
004C61D6 | 8B6C24 04                  | mov ebp,dword ptr ss:[esp+4]                               |ebp=call返回地址
0048718D | 8D6D 01                    | lea ebp,dword ptr ss:[ebp+1]                               |ebp=call返回地址+1
0056A3E4 | 896C24 04                  | mov dword ptr ss:[esp+4],ebp                               |[esp+4]=call返回地址+1
0056A3E8 | 66:0F47EB                  | cmova bp,bx                                                |
0056A3EC | 0FBFED                     | movsx ebp,bp                                               |
0056A3EF | BD E6224000                | mov ebp,test1_vmp.4022E6                                   |
004B2DCA | 8BAD 432F0800              | mov ebp,dword ptr ss:[ebp+82F43]                           |
004BF11F | 8DAD C713DE73              | lea ebp,dword ptr ss:[ebp+73DE13C7]                        |
004F561B | 872C24                     | xchg dword ptr ss:[esp],ebp                                |恢复ebp,esp[0]=api地址
                                        ret                                                         |ret返回到Api

Push Call mode

original code

.text:004099DF 56                                                           push    esi
.text:004099E0 8B 35 0C C0 45 00                                            mov     esi,ds:InitializeCriticalSection
.text:004099E6 FF 35 A4 41 41 00                                            push    lpCriticalSection ; lpCriticalSection

encrypt IAT call

004099DF | 56                         | push esi                                                   |
004099E0 | 53                         | push ebx                                                   |
004099E1 | E8 299B1600                | call test1_vmp.57350F                                      |
004099E6 | FF35 A4414100              | push dword ptr ds:[4141A4]                                 | 004141A4:"@kA"

code mov esi,ds:InitializeCriticalSection has changed to push ebx call test1_vmp.57350F

Thanks

unicorn

BlackBone

vmpfix

Scylla

zydis

spdlog