Full Disclosure: Re: Facebook URL Redirect Vulnerability

[Nathan Power <np () securitypentest com>]

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.securitypentest.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/079577.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.securitypentest.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
> ------------------------------------------------------------------
>
> _____________________________________________________________________________________________
>
> Please visit www.nhrs.org to subscribe to NHRS email announcements and updates.
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