Corrected bad coding (sorry)

Added OptEnum and OptPath
Checks for nil and empty
Added reference
Made AlterSerial an advanced option instead of always on

Author: Chris John Riley

modules/auxiliary/scanner/http/impersonate_ssl.rb

@@ -19,11 +19,14 @@ class Metasploit4 < Msf::Auxiliary
 	def initialize(info={})
 		super(update_info(info,
 			'Name'        => 'HTTP SSL Certificate Impersonation',
-			'Version'     => '$Revision$',
 			'Author'      => ' Chris John Riley',
+			'References'  =>
+					[
+						['URL', 'http://www.slideshare.net/ChrisJohnRiley/ssl-certificate-impersonation-for-shits-andgiggles']
+					],
 			'License'     => MSF_LICENSE,
 			'Description' => %q{
-					This module request a copy of the remote SSL certificate and creates a local
+				This module request a copy of the remote SSL certificate and creates a local
 				(self.signed) version using the information from the remote version. The module
 				then Outputs (PEM|DER) format private key / certificate and a combined version
 				for use in Apache or other Metasploit modules requiring SSLCert Inputs for private
@@ -34,46 +37,52 @@ def initialize(info={})
 		register_options(
 			[
 				Opt::RPORT(443),
-				OptString.new('OUT_FORMAT',       [true, "Output format PEM / DER", 'PEM']),
-				OptString.new('EXPIRATION',       [false, "Date the new cert should expire (e.g. 06 May 2012, Yesterday or Now)", '']),
-				OptString.new('PRIVKEY',          [false, "Sign the cert with your own CA private key ;)", '']),
-				OptString.new('PRIVKEY_PASSWORD', [false, "Password for private key specified in PRIV_KEY (if applicable)", '']),
-				OptString.new('CA_CERT',          [false, "CA Public certificate", '']),
-				OptString.new('ADD_CN',           [false, "Add CN to match spoofed site name (e.g. *.example.com)", '']),
+				OptEnum.new('OUT_FORMAT',         [true,  "Output format", 'PEM', ['DER','PEM']]),
+				OptString.new('EXPIRATION',       [false, "Date the new cert should expire (e.g. 06 May 2012, YESTERDAY or NOW)", nil]),
+				OptPath.new('PRIVKEY',            [false, "Sign the cert with your own CA private key", nil]),
+				OptString.new('PRIVKEY_PASSWORD', [false, "Password for private key specified in PRIV_KEY (if applicable)", nil]),
+				OptPath.new('CA_CERT',            [false, "CA Public certificate", nil]),
+				OptString.new('ADD_CN',           [false, "Add CN to match spoofed site name (e.g. *.example.com)", nil])
+			], self.class)
+
+		register_advanced_options(
+			[
+				OptBool.new('AlterSerial',        [false, "Alter the serial number slightly to avoif FireFox serial matching", true])
 			], self.class)
 	end
 
 	def run
 		print_status("Connecting to #{rhost}:#{rport}")
 
-		if (datastore['PRIVKEY'] != '' and datastore['CA_CERT'] != '')
-			print_status("Signing generated certificate with provided KEY and CA Certificate")
-			if datastore['PRIVKEY_PASSWORD'] != ''
+		if not datastore['PRIVKEY'].nil? and not datastore['CA_CERT'].nil?
+			print_status("Signing generated certificate with provided PRIVATE KEY and CA Certificate")
+			if not datastore['PRIVKEY_PASSWORD'].nil? and not datastore['PRIVKEY_PASSWORD'].empty?
 				ca_key = OpenSSL::PKey::RSA.new(File.read(datastore['PRIVKEY']), datastore['PRIVKEY_PASSWORD'])
 			else
 				ca_key = OpenSSL::PKey::RSA.new(File.read(datastore['PRIVKEY']))
 			end
 			ca = OpenSSL::X509::Certificate.new(File.read(datastore['CA_CERT']))
-		elsif (datastore['PRIVKEY'] != '' or datastore['CA_CERT'] != '')
+		elsif not datastore['PRIVKEY'].nil? or not datastore['CA_CERT'].nil?
+			# error if both PRIVKEY and CA_CERT are not BOTH provided
 			print_error("CA Certificate AND Private Key must be provided!")
 			return
 		end
 
 		begin
 			connect(true, {"SSL" => true}) # Force SSL even for RPORT != 443
-			cert  = OpenSSL::X509::Certificate.new(sock.peer_cert) # Get certificate from remote rhost
+			cert = OpenSSL::X509::Certificate.new(sock.peer_cert) # Get certificate from remote rhost
 			disconnect
 		rescue ::Rex::ConnectionRefused, ::Rex::HostUnreachable, ::Rex::ConnectionTimeout => e
 		rescue ::Timeout::Error, ::Errno::EPIPE => e
 			print_error(e.message)
 		end
 
-		if(not cert)
-			print_error("#{rhost} No certificate subject or CN found")
+		if not cert
+			print_error("#{rhost}:#{rport} No certificate subject or CN found")
 			return
 		end
 
-		print_status("Copying certificate #{cert.subject.to_s} from #{rhost}:#{rport}")
+		print_status("Copying certificate from #{rhost}:#{rport}\n#{cert.subject.to_s} ")
 		vprint_status("Original Certifcate Details\n\n#{cert.to_text}")
 
 		begin
@@ -89,21 +98,23 @@ def run
 		end
 
 		new_cert = OpenSSL::X509::Certificate.new
-		ef = OpenSSL::X509::ExtensionFactory.new#(nil,new_cert)
+		ef = OpenSSL::X509::ExtensionFactory.new
 
 		# Duplicate information from the remote certificate
 		entries = ['version','serial', 'subject', 'not_before','not_after']
 		entries.each do | ent |
 			eval("new_cert.#{ent} = cert.#{ent}")
 		end
 
-		if datastore['ADD_CN'] != ''
+		# add additional Common Name to the new cert
+		if not datastore['ADD_CN'].nil?  and not datastore['ADD_CN'].empty?
 			new_cert.subject = OpenSSL::X509::Name.new(new_cert.subject.to_a << ["CN", "#{datastore['ADD_CN']}"])
 			print_status("Adding #{datastore['ADD_CN']} to the end of the certificate subject")
 			vprint_status("Certificate Subject: #{new_cert.subject}")
 		end
 
-		if datastore['EXPIRATION'] != ''
+		if not datastore['EXPIRATION'].nil? and not datastore['EXPIRATION'].empty?
+			# alter the not_after and not_before dates
 			print_status("Altering certificate expiry information to #{datastore['EXPIRATION']}")
 
 			case datastore['EXPIRATION'].downcase
@@ -123,13 +134,21 @@ def run
 		end
 
 		# Alter serial to avoid duplicate issuer/serial detection
-		if (cert.serial.to_s.length > 1)
-			new_cert.serial = (cert.serial.to_s[0..-2] + rand(0xFF).to_s).to_i
+		if datastore['AlterSerial']
+			if (cert.serial.to_s.length > 1)
+				# alter last digits of the serial number
+				new_cert.serial = (cert.serial.to_s[0..-2] + rand(0xFF).to_s).to_i
+			else
+				# serial is too small, create random serial
+				vprint_error("The serial number of the original cert is too short. Creating new random serial")
+				new_cert.serial = rand(0xFFFF)
+			end
 		else
-			new_cert.serial = rand(0xFFFF)
+			# match serial number
+			new_cert.serial = cert.serial.to_s
 		end
 
-		if datastore['PRIVKEY'] != ''
+		if not datastore['PRIVKEY'].nil? and not datastore['PRIVKEY'].empty?
 			new_cert.public_key = ca_key.public_key
 			ef.subject_certificate = ca
 			ef.issuer_certificate = ca
@@ -140,7 +159,7 @@ def run
 			new_cert.public_key = new_key.public_key
 			ef.subject_certificate = new_cert
 			ef.issuer_certificate = new_cert
-			if datastore['ADD_CN'] != ''
+			if not datastore['ADD_CN'].nil? and not datastore['ADD_CN'].empty?
 				new_cert.issuer = new_cert.subject
 			else
 				new_cert.issuer = cert.subject
@@ -152,7 +171,7 @@ def run
 			ef.create_extension("subjectKeyIdentifier","hash"),
 		]
 
-		if datastore['PRIVKEY'] != ''
+		if not datastore['PRIVKEY'].nil? and not datastore['PRIVKEY'].empty?
 			new_cert.sign(ca_key, eval("OpenSSL::Digest::#{hashtype.upcase}.new"))
 			new_key = ca_key # Set for file output
 		else