SEC Consult SA-20121115-0 :: Applicure dotDefender WAF format- string vulnerability

From: SEC Consult Vulnerability Lab <>
To: bugtraq <>,
Subject: SEC Consult SA-20121115-0 :: Applicure dotDefender WAF format- string vulnerability

SEC Consult Vulnerability Lab Security Advisory < 20121115-0 >
              title: Applicure dotDefender WAF format string vulnerability
            product: dotDefender for Linux/Apache
 vulnerable version: <= 4.26
      fixed version: 5.00
         CVE number: -
             impact: Medium (needs preconditions)
              found: 2012-10-13
                 by: Bernhard Mueller
                     SEC Consult Vulnerability Lab

Vendor/product description:
dotDefender is a web application security solution (a Web Application
Firewall, or WAF) that offers strong, proactive security for your websites and
web applications.


Vulnerability overview/description:
dotDefender displays an error page when blocking an attack. The error page is
generated from a template which can contain various template variables. These
variables are expanded into a buffer first, the result of which is then passed
to AP_PRINTF() without checking for format string identifiers. Any remaining
format strings are interpreted by AP_PRINTF(), allowing for a format string
injection attack.

This is immediately exploitable by an unauthenticated attacker if the <%IP%>
template tag is used in the error page (not the case in the default template).
In this case an attacker can inject format strings in the "Host"-header. Other
attack vectors may exist if the attacker manages to access the dotDefender web
interface which requires a password.

Successful exploitation allows an attacker to execute arbitrary code on the

Proof of concept:

No proof-of-concept exploit will be released.

Vulnerable / tested versions:

The vulnerability has been tested with dotDefender 4.26 for Linux/Apache.

dotDefender for Windows is not affected.

Vendor contact timeline:
2012-10-17: Contacted vendor
2012-11: Fixed version is released
2012-11-15: SEC Consult releases security advisory

Upgrade to at least version 5.00 of dotDefender for Linux:

Advisory URL:

The SEC Consult Group

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EOF B. Mueller / November 2012

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