Re: Facebook URL Redirect Vulnerability

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

I appreciate that!
 
-J

        -----Original Message-----
        From: Nathan Power [mailto:np () securitypentest com] 
        Sent: Wednesday, March 02, 2011 10:46 AM
        To: Weir, Jason
        Cc: Full Disclosure
        Subject: Re: [Full-disclosure] Facebook URL Redirect
Vulnerability
        
        
        This rule can be subverted because of the content keyword.
        
        Below is an example:
        
http://apps.facebook.com/truthsaboutu/track.php?a=a&r=http://www.securit
ypentest.com
        
        Add two content keywords 'track.php?' and 'r='
        
        
        Nathan Power
        www.securitypentest.com
        
        
        
        
        On Mon, Feb 28, 2011 at 3:35 PM, Weir, Jason
<jason.weir () nhrs org> wrote:
        

                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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