Protect Your Assets
cancel
Showing results for 
Search instead for 
Did you mean: 

Re: Bypassing web application firewalls using HTTP headers

g33cko

Heh, nice catch.

I have not stumbled upon a similar thing but definately will keep in mind.

Thank you for sharing !

0 Kudos
About the Author

g33cko

Comments
g33cko

Heh, nice catch.

I have not stumbled upon a similar thing but definately will keep in mind.

Thank you for sharing !

Kevinff

This is an error of a WP security plugin i guess (so is the 418 error, i think it's of wp better security?).

I think (i may be wrong), this could happen with bad plugins that use the wrong headers to retrieve the real client ip, there might have many WP plugins (and other cms) out there that don't allow the user to specify which header to search for the real ip, and that try to get it from all possible headers.. This is so wrong!

I think that's always better to do it through the webserver instead of using those broken plugins, in nginx you can specify the header to look for the real ip, in apache rpaf too.

Great article.

Brian McHenry

That's a pretty wildly bad mis-configuration.  There's no reason the WAF should have to explicitly trust itself, and moreover, a cache server should never be treated as a trusted source, in any event.  And there's no good reason to trust the XFF header (of any name) to enable a bypass.


Even when counseling customers using large CDN's, the only way to ensure some integrity of an XFF header is to restrict the network-level permitted sources to the CDN IP's, and then use the XFF for more advanced correlation and mitigation (like IP reputation or geolocation).

MixALot

Great article!

 

Since this is your environment, can you tell us if the WAF in the test was used in a proxy configuration? This may be of no consequence for how the WAF determines how to block the source, but my question is whether the WAF will use the X-originating-IP to actually route traffic in any instance, or if this is decoupled with the TCP/IP info for the actual routing of the packets involved. I am wondering if a WAF as a proxy configuration would handle these blocks differently than an inline or promiscuous installation topology, or if this is of no real consequence? 

 

Or maybe I am looking at this all wrong :)

Wth2014
You may want to check CDNs as they have their own headers which you can add to your list. Good stuff.
Events
June 6 - 8, 2017
Las Vegas, Nevada
Discover 2017 Las Vegas
Join us for HPE Discover 2017 in Las Vegas. The event will be held at the Venetian | Palazzo from June 6-8, 2017.
Read more
Each Month in 2017
Online
Software Expert Days - 2017
Join us online to talk directly with our Software experts during online Expert Days. Find information here about past, current, and upcoming Expert Da...
Read more
View all
What's New
Posted to:
Original author:
View all