Red Hat Bugzilla – Bug 66905
chunk-encoded HTTP vulnerability
Last modified: 2007-03-26 23:54:08 EDT
Description of Problem: A new exploit has been identified in all versions of
Apache 1.x We are using Stronghold 3 and require a patch
Version-Release number of selected component (if applicable):
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CERT Advisory CA-2002-17 Apache Web Server Chunk Handling Vulnerability
Original release date: June 17, 2002
Last revised: --
A complete revision history can be found at the end of this file.
* Web servers based on Apache code versions 1.3 through 1.3.24
* Web servers based on Apache code versions 2.0 through 2.0.36
There is a remotely exploitable vulnerability in the handling of large
chunks of data in web servers that are based on Apache source code.
This vulnerability is present by default in configurations of Apache
web servers versions 1.3 through 1.3.24 and versions 2.0 through
2.0.36. The impact of this vulnerability is dependent upon the
software version and the hardware platform the server is running on.
Apache is a popular web server that includes support for chunk-encoded
data according to the HTTP 1.1 standard as described in RFC2616. There
is a vulnerability in the handling of certain chunk-encoded HTTP
requests that may allow remote attackers to execute arbitrary code.
The Apache Software Foundation has published an advisory describing
the details of this vulnerability. This advisory is available on their
web site at
For Apache versions 1.3 through 1.3.24 inclusive, this vulnerability
may allow the execution of arbitrary code by remote attackers. Several
sources have reported that this vulnerability can be used by intruders
to execute arbitrary code on Windows platforms. Additionally, the
Apache Software Foundation has reported that a similar attack may
allow the execution of arbitrary code on 64-bit UNIX systems.
For Apache versions 2.0 through 2.0.36 inclusive, the condition
causing the vulnerability is correctly detected and causes the child
process to exit. Depending on a variety of factors, including the
threading model supported by the vulnerable system, this may lead to a
denial-of-service attack against the Apache web server.
Apply a patch from your vendor
Apply a patch from your vendor to correct this vulnerability. The
CERT/CC has been informed by the Apache Software Foundation that the
patch provided in the ISS advisory on this topic does not completely
correct this vulnerability. More information about vendor-specific
patches can be found in the vendor section of this document. Because
the publication of this advisory was unexpectedly accelerated,
statements from all of the affected vendors were not available at
publication time. As additional information from vendors becomes
available, this document will be updated.
Upgrade to the latest version
The Apache Software Foundation has released two new versions of Apache
that correct this vulnerability. System administrators can prevent the
vulnerability from being exploited by upgrading to Apache version
1.3.25 or 2.0.39. The new versions of Apache will be available from
their web site at
Appendix A. - Vendor Information
This appendix contains information provided by vendors for this
advisory. As vendors report new information to the CERT/CC, we will
update this section and note the changes in our revision history. If a
particular vendor is not listed below, we have not received their
Apache Software Foundation
New versions of the Apache software are available from:
The Apache webserver shipped with Conectiva Linux is vulnerable to
this problem. New packages fixing this problem will be announced to
our mailing list after an official fix becomes available.
Cray, Inc. does not distribute Apache with any of its operating
IBM makes the Apache Server availble for AIX customers as a software
package under the AIX-Linux Affinity initiative. This package is
included on the AIX Toolbox for Linux Applications CD, and can be
downloaded via the IBM Linux Affinity website. The currently available
version of Apache Server is susceptible to the vulnerability described
here. We will update our Apache Server offering shortly to version
1.3.23, including the patch for this vulnerability; this update will
be made available for downloading by accessing this URL:
and following the instructions presented there.
Please note that Apache Server, and all Linux Affinity software, is
offered on an "as-is" basis. IBM does not own the source code for this
software, nor has it developed and fully tested this code. IBM does
not support these software packages.
We have verified that the Lotus Domino web server is not vulnerable to
this type of problem. Also, we do not ship Apache code with any Lotus
Microsoft does not ship the Apache web server.
NetApp systems are not vulnerable to this problem.
Red Hat distributes Apache 1.3 versions in all Red Hat Linux
distributions, and as part of Stronghold. However we do not distribute
Apache for Windows. We are currently investigating the issue and will
work on producing errata packages when an official fix for the problem
is made available. When these updates are complete they will be
available from the URL below. At the same time users of the Red Hat
Network will be able to update their systems using the 'up2date' tool.
The Unisphere Networks SDX-300 Service Deployment System (aka. SSC)
uses Apache 1.3.24. We are releasing Version 3.0 using Apache 1.3.25
soon, and will be issuing a patch release for SSC Version 2.0.3 in the
very near future.
The CERT/CC thanks Mark Litchfield for reporting this vulnerability to
the Apache Software Foundation, and Mark Cox for reporting this
vulnerability to the CERT/CC.
Author: Cory F. Cohen
Anyone care to give it a run?
Official errata packages will be available from the URL below shortly, once they
have gone through our QA and release procedure.
It has been proven to work on *nix/32, despite what Apache.org declared. Please
have a look at this code:
The RPM fix for this issue from Red Hat Network leaves the httpd stopped. It
does not restart it if it was started when the update agent process was started.
This seems like The Wrong Thing to do, IMHO.
Note that this bug was filed against the Stronghold product. New builds of
Stronghold 3 are now available from http://stronghold.redhat.com/sh3/ which
include a fix for this problem. For Red Hat Linux, see
http://rhn.redhat.com/errata/RHSA-2002-103.html as mentioned above.