Hello!
The problem is that a hacker can now post URL's that look like they're
going to your site on some forum or in an email. But when the user
actually clicks on the link, a custom header could redirect the user to
a malicious site. In the example, I used "EvilHeader", but it could be
any header, like an HTTP 301 redirect. Basically, the hacker can include
any header he wants in the response that the user is going to get when
he clicks on the link.
For a more detailed description of HTTP Response Splitting (which is on
the OWASP list of security vulnerabilities), you can check:
https://www.owasp.org/index.php/HTTP_Response_Splitting
http://www.acunetix.com/vulnerabilities/CRLF-injectionHTTP-respon.htm
http://packetstormsecurity.org/papers/general/whitepaper_httpresponse.pdf
http://www.infosecwriters.com/text_resources/pdf/HTTP_Response.pdf
Cheers,
Gert-Jan
*Gert-Jan Schouten
Java Developer*
Roboreus
175 High Holborn
London WC1V 7AA
T: +44 (0) 7832916802
E: [email protected]
Skype: gert.jan.schouten
On 03/11/11 12:49, Martin Grigorov wrote:
Hi,
Can you describe what exactly is the problem with these custom headers ?
On Thu, Nov 3, 2011 at 2:04 PM, Gert-Jan Schouten
<[email protected]> wrote:
Hello all,
When having a Wicket application installed on Tomcat and you call that
application through HTTP, Wicket is protected against HTTP Response
Splitting. However, when you call Tomcat through AJP (for example through an
apache httpd proxy), HTTP Response Splitting becomes possible.
To demonstrate, I created a simple application and called it through an AJP
proxy with the curl command:
curl --max-redirs 0 -Dfoo
'http:///myapp/home?wicket:bookmarkablePage=:org.apache.wicket.markup.html.pages.BrowserInfoPage&cto=Foobar%3f%0d%0aEvilHeader:%20SPLIT%2f-%0d%0aAnotherEvilHeader:%20HEADER'
Note the '%0d%0a', a CRLF in the request. When calling Wicket through
Tomcat, these are replaced by spaces, but when calling Wicket through AJP,
these are left intact, getting us the following response:
HTTP/1.1 302 Moved Temporarily
Date: Wed, 02 Nov 2011 14:34:32 GMT
Server: Apache
Set-Cookie: JSESSIONID=4F403B53D091B40F6C3FBC2321A2E348.pub-app04;
Path=/myapp; HttpOnly Location:
http://<ip-address>/myapp/Foobar;jsessionid=4F403B53D091B40F6C3FBC2321A2E348.pub-app04?
EvilHeader: SPLIT/-
AnotherEvilHeader: HEADER
Content-Length: 0
Connection: close
Content-Type: text/plain; charset=UTF-8
Here we have 2 Evil Headers, that could be inserted by hackers by adding
%0d%0a to the get-request.
Is there anything we can do about this? We use mod_jk 1.2.31 on our httpd
server.
Cheers!
Gert-Jan
--
*Gert-Jan Schouten
Java Developer*
