Re: Facebook URL Redirect Vulnerability

["Weir, Jason" <jason.weir () nhrs org>]

Here's a snort rule that will detect this 
 
alert tcp $HOME_NET any ->
[69.63.176.0/20,69.63.176.0/20,204.15.20.0/22] $HTTP_PORTS
(msg:"Facebook URL Redirect Vulnerability"; flow:established,to_server;
content:"GET"; nocase; http_method; content:"track.php?r="; nocase;
http_uri;
reference:lists.grok.org.uk/pipermail/full-disclosure/2011-February/0795
77.html; sid:xxxxxxx; rev:1;)
 
-J

        -----Original Message-----
        From: full-disclosure-bounces () lists grok org uk
[mailto:full-disclosure-bounces () lists grok org uk] On Behalf Of Nathan
Power
        Sent: Monday, February 28, 2011 12:43 PM
        To: Full Disclosure
        Subject: [Full-disclosure] Facebook URL Redirect Vulnerability
        
        
        
------------------------------------------------------------------
        1. Summary:
        
        Once the victim clicks on a specially crafted Facebook URL they
can be redirected to a malicious website.
        
------------------------------------------------------------------
        2. Description:
        
        Facebook applications use of 'track.php?r=' doesn't sanitize the
redirection input properly.  This allows an attacker to input any URL
that a victim will get redirected too.  It is not required for the
victim to be login to Facebook for this attack to work.
        
        The following is an example of a vulnerable URL:
        
http://apps.facebook.com/truthsaboutu/track.php?r=http://www.securitypen
test.com
        
        The following Google search query can be used to find vulnerable
URLs:
        site:facebook.com inurl:"track.php?" inurl:"r="
        
------------------------------------------------------------------
        3. Impact:
        
        Potentially allow an attacker to compromise a victim's Facebook
account and/or computer system.
        
------------------------------------------------------------------
        4. Affected Products:
        
        www.facebook.com
        
------------------------------------------------------------------
        5. Solution:  None
        
------------------------------------------------------------------
        6. Time Table:
        
        2/27/2011 Reported Vulnerability to the Vendor
        
------------------------------------------------------------------
        7. Credits:
        
        Discovered by Nathan Power
        www.securitypentest.com
        
------------------------------------------------------------------
        

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