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Category:   Application (Security)  >   Mod_ssl Vendors:
(Fedora Issues Fix for RH Linux) Apache mod_ssl Stack Overflow in ssl_util_uuencode_binary() May Let Remote Users Execute Arbitrary Code
SecurityTracker Alert ID:  1011704
SecurityTracker URL:
CVE Reference:   CVE-2004-0488   (Links to External Site)
Date:  Oct 15 2004
Impact:   Execution of arbitrary code via network, User access via network
Fix Available:  Yes  Vendor Confirmed:  Yes  

Description:   A buffer overflow vulnerability was reported in Apache mod_ssl. A remote user may be able to execute arbitrary code on the target system in certain situations.

Georgi Guninski reported that the ssl_util_uuencode_binary() function in 'ssl_util.c' may allow a remote user to supply a specially crafted Subject-DN in a client certificate to trigger the overflow. According to OpenPKG, the overflow resides in the "SSLOptions +FakeBasicAuth" implementation of mod_ssl and can be triggered if the Subject-DN is longer than 6 KB and mod_ssl is configured to trust the certificate's issuing CA.

Impact:   A remote user may be able to execute arbitrary code on the target system in certain cases.
Solution:   Fedora has released a fix, available at:

Red Hat Linux 7.3:



The SHA1 verification checksums are:


Vendor URL: (Links to External Site)
Cause:   Boundary error
Underlying OS:  Linux (Red Hat Linux)
Underlying OS Comments:  7.3

Message History:   This archive entry is a follow-up to the message listed below.
May 28 2004 Apache mod_ssl Stack Overflow in ssl_util_uuencode_binary() May Let Remote Users Execute Arbitrary Code

 Source Message Contents

Subject:  [Full-Disclosure] [FLSA-2004:1888] Updated mod_ssl package fixes Apache security

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               Fedora Legacy Update Advisory

Synopsis:          Updated mod_ssl package fixes Apache security
Advisory ID:       FLSA:1888
Issue date:        2004-10-13
Product:           Red Hat Linux
Keywords:          Bugfix
Cross references:
CVE Names:         CAN-2004-0488 CAN-2004-0700

1. Topic:

Updated mod_ssl packages that fix minor security issues in the Apache
Web server are now available.

The Apache HTTP Server is a powerful, full-featured, efficient, and
freely-available Web server.

2. Relevant releases/architectures:

Red Hat Linux 7.3 - i386

3. Problem description:

A stack buffer overflow was discovered in mod_ssl which can be triggered
if using the FakeBasicAuth option. If mod_ssl is sent a client
certificate with a subject DN field longer than 6000 characters, a stack
overflow can occur if FakeBasicAuth has been enabled. In order to
exploit this issue the carefully crafted malicious certificate would
have to be signed by a Certificate Authority which mod_ssl is configured
to trust. The Common Vulnerabilities and Exposures project
( has assigned the name CAN-2004-0488 to this issue.

A format string issue was discovered in mod_ssl for Apache 1.3 which can
be triggered if mod_ssl is configured to allow a client to proxy to
remote SSL sites. In order to exploit this issue, a user who is
authorized to use Apache as a proxy would have to attempt to connect to
a carefully crafted hostname via SSL. The Common Vulnerabilities and
Exposures project ( has assigned the name CAN-2004-0700 to
this issue.

All users of the Apache HTTP Server are advised to upgrade to these
erratum packages, which contain a backported fix and are not vulnerable
to these issues.

4. Solution:

Before applying this update, make sure all previously released errata
relevant to your system have been applied.

To update all RPMs for your particular architecture, run:

rpm -Fvh [filenames]

where [filenames] is a list of the RPMs you wish to upgrade.  Only those
RPMs which are currently installed will be updated.  Those RPMs which
are not installed but included in the list will not be updated.  Note
that you can also use wildcards (*.rpm) if your current directory *only*
contains the desired RPMs.

Please note that this update is also available via yum and apt.  Many
people find this an easier way to apply updates.  To use yum issue:

yum update

or to use apt:

apt-get update; apt-get upgrade

This will start an interactive process that will result in the
appropriate RPMs being upgraded on your system.  This assumes that you
have yum or apt-get configured for obtaining Fedora Legacy content.
Please visit http://www for directions on how to
configure yum and apt-get.

5. Bug IDs fixed: - bug #1708 - bug #1888

6. RPMs required:

Red Hat Linux 7.3:



7. Verification:

SHA1 sum                                 Package Name


These packages are GPG signed by Fedora Legacy for security.  Our key is
available from http://www.fedoralegacy org/about/security.php

You can verify each package with the following command:

    rpm --checksig -v <filename>

If you only wish to verify that each package has not been corrupted or
tampered with, examine only the sha1sum with the following command:

    sha1sum <filename>

8. References:

9. Contact:

The Fedora Legacy security contact is <>. More
project details at


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Full-Disclosure - We believe in it.


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