http response splitting vulnerability
khansen at charityweb.net
Wed Aug 5 06:58:46 MSD 2009
Our server is checked each day by McAffee to see if there are any
It found one that I'm not sure what to do. Here's the description from
HTTP response splitting is the ability for an attacker to modify the
headers of an HTTP response due to lack of input validation on requests
that are sent to the application server.
A vulnerable web application or web server allows the user to insert a
Carriage Return (%0D or \r) and/or a Line Feed (%0A or \n) into the
headers of an HTTP response. This is usually done by sending modified
requests to the web application and the web application responding with
the user supplied data being inserted into a header. The attacker then
constructs and attack using a CRLF (Carriage Return-Line Feed) attack
that has the client interpret the data as 2 separate responses.
Here's the proposed solution:
All input that is sent to a web application should not be trusted and
should be assumed malicious. Characters such as Carriage Return (CR) and
Line Feed (LF) should be removed from all requests before being
interpreted by the web application server.
An attacker can also use encoded Carriage Returns and Line Feeds to
exploit the web server, and user-specified Carriage Returns and Line
Feeds serve no business purpose on a web server. Filter the following
characters from all user supplied input:
How can I implement this fix in nginx? I'm using it as a reverse proxy.
More information about the nginx