CERT/CC Vulnerability Note VU#395412

Overview

A vulnerability in a common Apache HTTP server module, mod_rewrite, could allow a remote attacker to execute arbitrary code on an affected web server.

Description

The Apache HTTP server distribution includes a number of supplemental modules that provide additional functionality to the web server. One of these modules, mod_rewrite, provides a rule-based rewriting engine to rewrite requested URLs "on the fly" based on regular expressions.

An off-by-one error exists in the ldap scheme handling in mod_rewrite. For some RewriteRules, specifically those where the remote user can influence the beginning of a rewritten URL and that do not include any of the following flags: Forbidden (F), Gone (G), or NoEscape (NE), this could lead to a pointer being written out of bounds. This flaw causes a remotely exploitable vulnerability on web servers that have mod_rewrite enabled (configuration directive "RewriteEngine on") and configured to use certain rules. For example, rules with this format expose the vulnerability:

RewriteRule fred/(.*) $1

While rules with this format do not expose the vulnerability:

RewriteRule fred/(.*) joe/$1

The versions of the mod_rewrite module supplied with the Apache HTTP server versions

1.3 branch from 1.3.28
2.0 branch from 2.0.46
2.2 branch from 2.2.0

are vulnerable to this issue but earlier versions are not. The Apache Software Foundation notes that mod_rewrite is not enabled and configured as a normal default, however it is a commonly used module and may be provided in a vulnerable configuration by redistributors.

Impact

An attacker may be able to execute arbitrary code in the context of the web server user (e.g., "apache", "httpd", "nobody", "SYSTEM", etc.). The Apache Software Foundation notes that, due to the nature of the underlying flaw, successful exploitation is dependent upon the stack frame layout of apache running on the target host.

Solution

Apply a patch from the vendor

Patches have been released to address this vulnerability. Please see the Systems Affected section of this document for more details.

Workarounds

Disable mod_rewrite if it is not required in your web server configuration. Instructions for doing this can be found in the Apache HTTP server documentation. Sites, particularly those that are not able to apply the patches, are encouraged to implement this workaround.

Vendor Information

395412

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Apache HTTP Server Project Affected

Fedora Project Affected

Gentoo Linux Affected

Hewlett-Packard Company Affected

Notified: July 26, 2006 Updated: September 15, 2006

Status

Affected

Vendor Statement

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

SUPPORT COMMUNICATION - SECURITY BULLETIN

Document ID: c00760969

Version: 1

HPSBUX02145 SSRT061202 rev.1 - HP-UX running Apache Remote Execution of Arbitrary Code,
Denial of Service (DoS), and Unauthorized Access

NOTICE: The information in this Security Bulletin should be acted upon as soon as possible.

Release Date: 2006-08-25
Last Updated: 2006-08-28

Potential Security Impact: Remote execution of arbitrary code, Denial of Service (DoS),
and unauthorized access.

Source: Hewlett-Packard Company, HP Software Security Response Team

VULNERABILITY SUMMARY
Potential security vulnerabilities have been identified with Apache running on HP-UX.
These vulnerabilities could be exploited remotely to allow execution of arbitrary code,
Denial of Service (DoS), or unauthorized access.

References: CVE-2006-3747, CVE-2005-3352, CVE-2005-3357

SUPPORTED SOFTWARE VERSIONS*: ONLY impacted versions are listed.
HP-UX B.11.00, B.11.11, B.11.23 running Apache-based Web Server prior to v.2.0.58.

BACKGROUND

The following potential security vulnerabilities are resolved in the
software update listed below:

CVE-2006-3747 (cve.mitre.org): Off-by-one error in the ldap scheme handling.
CVE-2005-3352 (cve.mitre.org): mod_ssl NULL pointer dereference.
CVE-2005-3357 (cve.mitre.org): Remote arbitrary code execution.

AFFECTED VERSIONS

For IPv4:
HP-UX B.11.00
HP-UX B.11.11
===========
hpuxwsAPACHE
action: install revision A.2.0.58.00 or subsequent
action: restart Apache

For IPv6:
HP-UX B.11.11
===========
hpuxwsAPACHE,revision=B.1.0.00.01
hpuxwsAPACHE,revision=B.1.0.07.01
hpuxwsAPACHE,revision=B.1.0.08.01
hpuxwsAPACHE,revision=B.1.0.09.01
hpuxwsAPACHE,revision=B.1.0.10.01
hpuxwsAPACHE,revision=B.2.0.48.00
hpuxwsAPACHE,revision=B.2.0.49.00
hpuxwsAPACHE,revision=B.2.0.50.00
hpuxwsAPACHE,revision=B.2.0.51.00
hpuxwsAPACHE,revision=B.2.0.52.00
hpuxwsAPACHE,revision=B.2.0.53.00
hpuxwsAPACHE,revision=B.2.0.54.00
hpuxwsAPACHE,revision=B.2.0.55.00
action: install revision B.2.0.58.00 or subsequent
action: restart Apache

HP-UX B.11.23
===========
hpuxwsAPACHE
action: install revision B.2.0.58.00 or subsequent
action: restart Apache

END AFFECTED VERSIONS

RESOLUTION

HP has made the following patches and software updates available to resolve the issue.

Software updates for the Apache-based Web Server are available from:

http://h20293.www2.hp.com/cgi-bin/swdepot_parser.cgi/cgi/
displayProductInfo.pl?productNumber=HPUXWSSUITE

HP-UX B.11.00, B.11.11 and HP-UX B.11.23 require the Apache-based Web Server
v.2.0.58.00 or subsequent.

Apache Update Procedure

Check for Apache Installation
- ----------------------------
To determine if the Apache web server from HP is installed on your system,
use Software Distributor's swlist command. All three revisions of the product
may co-exist on a single system.
For example, the results of the command
swlist -l product | grep -i apache
hpuxwsAPACHE B.2.0.55.00 HP-UX Apache-based Web Server

Stop Apache
- -------------
Before updating, make sure to stop any previous Apache binary. Otherwise,
the previous binary will continue running, preventing the new one from starting,
although the installation would be successful. After determining which Apache is
installed, stop Apache with the following commands:
for hpuxwsAPACHE: /opt/hpws/apache[32]/bin/apachectl stop

Download and Install Apache
- ---------------------------
Download Apache from Software Depot:

http://h20293.www2.hp.com/cgi-bin/swdepot_parser.cgi/cgi/
displayProductInfo.pl?productNumber=HPUXWSSUITE

Verify successful download by comparing the cksum with the value
specified on the installation web page.

Use SD to swinstall the depot.
Installation of this new revision of HP Apache over an existing HP Apache
installation is supported, while installation over a non-HP Apache is NOT supported.

Removing Apache Installation
- ----------------------------
If you prefer to remove Apache from your system instead of installing a newer revision
to resolve the security problem, use both Software Distributor's "swremove" command
and also "rm -rf" the home location as specified in the rc.config.d file "HOME" variables.
%ls /etc/rc.config.d | \ grep apache hpapache2conf hpws_apache[32]conf

MANUAL ACTIONS: Yes - Update plus other actions
Install the revision of the product.

PRODUCT SPECIFIC INFORMATION
HP-UX Security Patch Check: Security Patch Check revision B.02.00 analyzes all
HP-issued Security Bulletins to provide a subset of recommended actions that potentially
affect a specific HP-UX system. For more information: http://software.hp.com/portal/swdepot/displayProductInfo.do?productNumber=B6834AA

HISTORY: rev.1 - 28 August 2006 Initial Release

Support: For further information, contact normal HP Services
support channel.

Report: To report a potential security vulnerability with any HP
supported product, send Email to: security-alert@hp.com. It is
strongly recommended that security related information being
communicated to HP be encrypted using PGP, especially exploit
information. To get the security-alert PGP key, please send an
e-mail message as follows:
To: security-alert@hp.com
Subject: get key

Subscribe: To initiate a subscription to receive future HP
Security Bulletins via Email:
http://h30046.www3.hp.com/driverAlertProfile.php?regioncode=NA&
langcode=USENG&jumpid=in_SC-GEN__driverITRC&topiccode=ITRC

On the web page: ITRC security bulletins and patch sign-up
Under Step1: your ITRC security bulletins and patches
- check ALL categories for which alerts are required and
continue.
Under Step2: your ITRC operating systems
- verify your operating system selections are checked and
save.

To update an existing subscription:
http://h30046.www3.hp.com/subSignIn.php
Log in on the web page:
Subscriber's choice for Business: sign-in.
On the web page:
Subscriber's Choice: your profile summary
- use Edit Profile to update appropriate sections.

To review previously published Security Bulletins visit:
http://www.itrc.hp.com/service/cki/secBullArchive.do

* The Software Product Category that this Security Bulletin
relates to is represented by the 5th and 6th characters of the
Bulletin number in the title:

GN = HP General SW,
MA = HP Management Agents,
MI = Misc. 3rd party SW,
MP = HP MPE/iX,
NS = HP NonStop Servers,
OV = HP OpenVMS,
PI = HP Printing & Imaging,
ST = HP Storage SW,
TL = HP Trusted Linux,
TU = HP Tru64 UNIX,
UX = HP-UX,
VV = HP Virtual Vault

System management and security procedures must be reviewed
frequently to maintain system integrity. HP is continually
reviewing and enhancing the security features of software products
to provide customers with current secure solutions.

"HP is broadly distributing this Security Bulletin in order to
bring to the attention of users of the affected HP products the
important security information contained in this Bulletin. HP
recommends that all users determine the applicability of this
information to their individual situations and take appropriate
action. HP does not warrant that this information is necessarily
accurate or complete for all user situations and, consequently, HP
will not be responsible for any damages resulting from user's use
or disregard of the information provided in this Bulletin. To the
extent permitted by law, HP disclaims all warranties, either
express or implied, including the warranties of merchantability
and fitness for a particular purpose, title and non-infringement."

(c)Copyright 2006 Hewlett-Packard Development Company, L.P.
Hewlett-Packard Company shall not be liable for technical or
editorial errors or omissions contained herein. The information
provided is provided "as is" without warranty of any kind. To the
extent permitted by law, neither HP nor its affiliates,
subcontractors or suppliers will be liable for incidental, special
or consequential damages including downtime cost; lost profits;
damages relating to the procurement of substitute products or
services; or damages for loss of data, or software restoration.
The information in this document is subject to change without
notice. Hewlett-Packard Company and the names of Hewlett-Packard
products referenced herein are trademarks of Hewlett-Packard
Company in the United States and other countries. Other product
and company names mentioned herein may be trademarks of their
respective owners.
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Vendor Information

The vendor has not provided us with any further information regarding this vulnerability.

Mandriva, Inc. Affected

OpenPKG Affected

Oracle Corporation Affected

SUSE Linux Affected

Slackware Linux Inc. Affected

Ubuntu Affected

Apple Computer, Inc. Not Affected

Fujitsu Not Affected

Hitachi Not Affected

Juniper Networks, Inc. Not Affected

Openwall GNU/*/Linux Not Affected

Red Hat, Inc. Not Affected

Conectiva Inc. Unknown

Cray Inc. Unknown

Debian GNU/Linux Unknown

EMC, Inc. (formerly Data General Corporation) Unknown

Engarde Secure Linux Unknown

F5 Networks, Inc. Unknown

FreeBSD, Inc. Unknown

IBM Corporation Unknown

IBM Corporation (zseries) Unknown

IBM eServer Unknown

Immunix Communications, Inc. Unknown

Ingrian Networks, Inc. Unknown

MontaVista Software, Inc. Unknown

NEC Corporation Unknown

NetBSD Unknown

Nokia Unknown

Novell, Inc. Unknown

OpenBSD Unknown

QNX, Software Systems, Inc. Unknown

Silicon Graphics, Inc. Unknown

Sony Corporation Unknown

Sun Microsystems, Inc. Unknown

The SCO Group Unknown

Trustix Secure Linux Unknown

Turbolinux Unknown

Unisys Unknown

Wind River Systems, Inc. Unknown

View all 43 vendors View less vendors

CVSS Metrics

Group	Score	Vector
Base
Temporal
Environmental

References

Acknowledgements

Thanks to Mark Cox of the Apache Software Foundation for reporting this vulnerability. Mark, in turn, credits Mark Dowd of McAfee AVERT Labs with reporting this issue.

This document was written by Chad R Dougherty.

Other Information

CVE IDs:	CVE-2006-3747
Severity Metric:	6.48
Date Public:	2006-07-27
Date First Published:	2006-07-28
Date Last Updated:	2006-10-18 12:52 UTC
Document Revision:	43

Software Engineering Institute

CERT Coordination Center

Apache mod_rewrite contains off-by-one error in ldap scheme handling

Vulnerability Note VU#395412

Overview

Description

Impact

Solution

Vendor Information

Apache HTTP Server Project Affected

Fedora Project Affected

Gentoo Linux Affected

Hewlett-Packard Company Affected

Mandriva, Inc. Affected

OpenPKG Affected

Oracle Corporation Affected

SUSE Linux Affected

Slackware Linux Inc. Affected

Ubuntu Affected

Apple Computer, Inc. Not Affected

Fujitsu Not Affected

Hitachi Not Affected

Juniper Networks, Inc. Not Affected

Openwall GNU/*/Linux Not Affected

Red Hat, Inc. Not Affected

Conectiva Inc. Unknown

Cray Inc. Unknown

Debian GNU/Linux Unknown

EMC, Inc. (formerly Data General Corporation) Unknown

Engarde Secure Linux Unknown

F5 Networks, Inc. Unknown

FreeBSD, Inc. Unknown

IBM Corporation Unknown

IBM Corporation (zseries) Unknown

IBM eServer Unknown

Immunix Communications, Inc. Unknown

Ingrian Networks, Inc. Unknown

MontaVista Software, Inc. Unknown

NEC Corporation Unknown

NetBSD Unknown

Nokia Unknown

Novell, Inc. Unknown