Public Vulnerability Reports

Novell eDirectory NMAS BerDecodeLoginDataRequeset DoS Vulnerability

10.27.06

BACKGROUND

Novell eDirectory is a cross-platform lightweight directory access protocol (LDAP) server. Additionally, eDirectory implements NMAS which stands for Novell Modular Authentication System. More information can be found on Novell's web site at http://www.novell.com/products/edirectory/

DESCRIPTION

Remote exploitation of a denial of service (DoS) vulnerability in Novell Inc.'s eDirectory product could allow an attacker to force the running daemon to cease servicing requests.

The problem specifically exists due to a pointer handling mistake within the BerDecodeLoginDataRequest function within the libnmasldap.so module. When a specially crafted login request is encountered, this function loops based on a length value supplied in the request. In this loop, a nested pointer value is incremented at the wrong level. This results in a buffer length parameter that is on the stack being used as a memory address for ber_get_int(). This value does not appear to be influenced in any way by attacker supplied input. Invalid memory access will lead to a segmentation violation, crashing the process.

ANALYSIS

Successful exploitation of this vulnerability could allow an attacker to crash the server process. No credentials are required.

DETECTION

iDefense has confirmed the existence of this vulnerability within versions 8.8 and 8.8.1 of Novell's eDirectory product. The vulnerability was tested and confirmed to exist on both Linux and Solaris.

WORKAROUND

iDefense is unaware of any viable workaround for this issue.

VENDOR RESPONSE

Novell has addressed this issue in version 2.0.3 of Security Services. To obtain the updated version please refer to the following quoted vendor response:

"Search for "Security Services" at the Novell Downloads Web site (http://download.novell.com)and download the necessary platform-specific download for the Security Services 2.0.3 patch.

* For NetWare - select ss203_NW.tgz
* For Linux, Solaris, HP-UX, and AIX - select ss203_SLAH.tgz
* For Windows - select ss_setup.exe"

CVE INFORMATION

The Common Vulnerabilities and Exposures (CVE) project has assigned the name CVE-2006-4521 to this issue. This is a candidate for inclusion in the CVE list (http://cve.mitre.org),which standardizes names for security problems.

DISCLOSURE TIMELINE

08/17/2006 Initial vendor notification
08/18/2006 Initial vendor response
10/06/2006 Second vendor notification
10/27/2006 Coordinated public disclosure

CREDIT

The discoverer of this vulnerability wishes to remain anonymous.

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LEGAL NOTICES

Copyright © 2006 Verisign, Inc.

Permission is granted for the redistribution of this alert electronically. It may not be edited in any way without the express written consent of iDefense. If you wish to reprint the whole or any part of this alert in any other medium other than electronically, please email customerservice@idefense.com for permission.

Disclaimer: The information in the advisory is believed to be accurate at the time of publishing based on currently available information. Use of the information constitutes acceptance for use in an AS IS condition. There are no warranties with regard to this information. Neither the author nor the publisher accepts any liability for any direct, indirect, or consequential loss or damage arising from use of, or reliance on, this information.