IBM Lotus Domino Server LDAP DoS Vulnerability

iDEFENSE Security Advisory 02.10.06
http://www.idefense.com/intelligence/vulnerabilities/display.php?id=389
February 10, 2006

I. BACKGROUND

IBM Lotus Domino Server software provides messaging, calendaring and
scheduling capabilities on a variety of operating systems. More
information about the product is available from:

    http://www.lotus.com/products/product4.nsf/wdocs/dominohomepage

II. DESCRIPTION

Remote exploitation of a denial of service vulnerability in IBM Corp.'s
Lotus Domino LDAP server allows attackers to crash the service, thereby
preventing legitimate access. iDEFENSE is currently unaware of exploits
for this vulnerability other than those maintained by iDEFENSE Labs.
Vendor patches for this iDEFENSE exclusive report are currently
unavailable. A workaround has been provided.

The problem specifically exists within the LDAP server "nldap.exe." When
sending a specially crafted bind request with a long string to the LDAP
server port (389), a NULL pointer dereference occurs, resulting in a
crash of the process.

III. ANALYSIS

Exploitation of this vulnerability allows unauthenticated remote
attackers to crash the LDAP service, thereby preventing legitimate
usage. This attack takes little resources to launch and can be repeated
to ensure that an unpatched computer is unable to recover even after the
administrator manually restarts the service.

IV. DETECTION

iDEFENSE has confirmed the existence of this vulnerability in Lotus
Domino Server version 6.5.4. It is suspected that earlier versions of
Lotus Domino Server are also affected.

V. WORKAROUND

Employ firewalls, access control lists or other TCP/UDP restriction
mechanisms to limit access to systems and services. More specifically,
limit access to TCP port 389 on the LDAP server to only allow trusted
hosts to connect.

VI. VENDOR RESPONSE

The vendor has addressed this issue in the following products:

 - IBM Lotus Notes/Domino 6.5.4 FP2
 - IBM Lotus Notes/Domino 6.5.5
 - IBM Lotus Notes/Domino 7.0.1
 
The vendor has published the following technote which details patching
procedures:

  http://www-1.ibm.com/support/docview.wss?rs=463&uid=swg21229907

VII. CVE INFORMATION

The Common Vulnerabilities and Exposures (CVE) project has assigned the
name CAN-2005-2712 to this issue. This is a candidate for inclusion in
the CVE list (http://cve.mitre.org), which standardizes names for
security problems.

VIII. DISCLOSURE TIMELINE

08/23/2005  Initial vendor notification
08/23/2005  Initial vendor response
02/10/2006  Coordinated public disclosure

IX. CREDIT

Sebastian Apelt is credited with the discovery of this vulnerability.

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X. LEGAL NOTICES

Copyright © 2006 iDEFENSE, Inc.

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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.