Archive for February 9th, 2013

Malware Analysis Patterns (Part 22)

Saturday, February 9th, 2013

Raw Pointer pattern is about pointers without matching symbol files. They may be in the expected module range or in some other known module range in the form of module+offset or can be completely out of range of any module from the loaded module list and therefore just a number. For example, usually we have certain structures or arrays (tables) where we expect pointers with matching symbols such as IAT, IDT and 32-bit SSDT where an occurrence of a raw pointer immediately triggers a suspicion such as in this Import Address Table from ProcessA:

[...]
00000001`3f8a9048 00000000`76e282d0 ntdll!RtlSizeHeap
00000001`3f8a9050 00000000`76bf9070 kernel32!GetStringTypeWStub
00000001`3f8a9058 00000000`76c03580 kernel32!WideCharToMultiByteStub
00000001`3f8a9060 00000000`76e33f20 ntdll!RtlReAllocateHeap
00000001`3f8a9068 00000000`76e533a0 ntdll!RtlAllocateHeap
00000001`3f8a9070 00000000`76bfc420 kernel32!GetCommandLineWStub
00000001`3f8a9078 00000001`3f8a1638 ProcessA+0×10ac
00000001`3f8a9080 00000000`76c2cc50 kernel32!IsProcessorFeaturePresent
00000001`3f8a9088 00000000`76c02d60 kernel32!GetLastErrorStub
00000001`3f8a9090 00000000`76c02d80 kernel32!SetLastError
00000001`3f8a9098 00000000`76bf3ee0 kernel32!GetCurrentThreadIdStub
[…]

Note that structures are not limited to the above and can me any OS or even application specific structure where we have symbol files. Raw pointers that are outside of expected module range are covered in the next pattern.

- Dmitry Vostokov @ DumpAnalysis.org + TraceAnalysis.org -

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Malware Analysis Patterns (Part 21)

Saturday, February 9th, 2013

Hooksware pattern originally came from memory dump analysis pattern catalog and is too general for malware analysis pattern catalog. So we decided to factor out 3 separate patterns. The first one is called Patched Code and includes cases such as in-place patching:

0:004> u ntdll!ZwQueryDirectoryFile
ntdll!ZwQueryDirectoryFile:
77814db4 b8da000000      mov     eax,0DAh
77814db9 bae8af0500      mov     edx,5AFE8h
77814dbe ff12            call    dword ptr [edx]
77814dc0 c22c00          ret     2Ch
77814dc3 90              nop
ntdll!NtQueryDirectoryObject:
77814dc4 b8db000000      mov     eax,0DBh
77814dc9 ba0003fe7f      mov     edx,offset SharedUserData!SystemCallStub (7ffe0300)
77814dce ff12            call    dword ptr [edx]

and detour patching:

0:004> u wininet!InternetReadFile
wininet!InternetReadFile:
7758654b e98044ac88      jmp     0004a9d0
77586550 83ec24          sub     esp,24h
77586553 53              push    ebx
77586554 56              push    esi
77586555 57              push    edi
77586556 33ff            xor     edi,edi
77586558 393db8116277    cmp     dword ptr [wininet!GlobalDataInitialized (776211b8)],edi
7758655e 897df4          mov     dword ptr [ebp-0Ch],edi

In case of WinDbg such pattern is usually detected on the crash spot such as from RIP Stack Trace or from !chkimg command output.

- Dmitry Vostokov @ DumpAnalysis.org + TraceAnalysis.org -

Posted in Assembly Language, Crash Dump Analysis, Malware Analysis, Malware Patterns, Victimware, Victimware Analysis | No Comments »