WebApp Sec mailing list archives
Re: BBCode [IMG] [/IMG] Tag Vulnerability
From: "Tony Stahler" <TStahler () tempographics com>
Date: Tue, 23 Aug 2005 09:20:03 -0500
If you wanted to use the script to check it, yet not have to retrieve the image every time you could have your server download the image during the post request (assuming it was a reasonable size..) ... check it, and then have the link be local from that point onward. This would open more possibilities for exploitation as far as denial of service attacks though (if your server is downloading it each time, or if it downloads it once), both for your server and for the server you're requesting it from. An example: I sign up for a bunch of accounts on one forum, or even multiple forums using this software - then have all the accounts post at the same time, with multiple images from the same site... the server(s) then effectively (D)DOS the target server. It would also work against your server, but in reverse, using a bunch of accounts (through proxies if necessary) and requesting as many images from fast servers as possible.. You'd probably be better off just deciding which image file types you consider safe for users... i.e. you probably don't want to allow flash... and only allow images with those extensions. Making sure images are safe isn't really you're responsibility, it's the responsibility of the image standard, and the browser displaying the information. Just my thoughts, Tony
Paul Laudanski <zx () castlecops com> 08/22/05 11:12PM >>>
On Mon, 22 Aug 2005, Christopher Kunz wrote:
Or, you could just disallow remote images altogether. It kinda boils
down to a
security vs. feature set question...
This is very interesting indeed. I was originally approaching this 'problem' from a strictly local host perspective (where the website resides) rather than from a remote attack. You're reply set me straight on that one. There ought to be a more creative way to monitor this stuff than just moving it from GET to POST (and POST in itself is not fool proof). I'm going to munch on this. Paul http://castlecops.com ________ Information from Computer Cops, L.L.C. ________ This message was checked by NOD32 Antivirus System for Linux Mail Server. part000.txt - is OK http://castlecops.com
Current thread:
- Re: BBCode [IMG] [/IMG] Tag Vulnerability Paul Laudanski (Aug 22)
- Re: [Full-disclosure] Re: BBCode [IMG] [/IMG] Tag Vulnerability Christopher Kunz (Aug 22)
- Re: BBCode [IMG] [/IMG] Tag Vulnerability Paul Laudanski (Aug 22)
- <Possible follow-ups>
- Re: BBCode [IMG] [/IMG] Tag Vulnerability Tony Stahler (Aug 23)
- Re: BBCode [IMG] [/IMG] Tag Vulnerability Zak McGregor (Aug 23)
- Re: BBCode [IMG] [/IMG] Tag Vulnerability Christopher Kunz (Aug 23)
- Re: BBCode [IMG] [/IMG] Tag Vulnerability Paul Laudanski (Sep 08)
- Re: BBCode [IMG] [/IMG] Tag Vulnerability Christopher Canova (Aug 27)
- Re: [Full-disclosure] Re: BBCode [IMG] [/IMG] Tag Vulnerability Christopher Kunz (Aug 22)