Vulnerability Report For Netscape Servers Denial of Service

Advisory ID Internal

Bugtraq ID: 1867

CVE Name: Non currently assigned.

Title: Netscape servers Denial of Service

Class: Denial of Service

Remotely Exploitable: Yes

Locally Exploitable: Yes

Release Mode: USER RELEASE

Communications with the vendor have been remarkably difficult and to a large degree unproductive. Our last point of contact was October 18, 2000. This last communication stated that they would getting back to us shortly.
Twelve days and several emails later we have decided to release without vendor support as it seems unlikely to be forthcoming.

Vulnerability Description:

A bug in several components of the Netscape Servers suite of products allows and attacker to successfully conduct a denial of service attack against the vulnerable systems.

The Netscape Certificate Management System has also several server components that share the problem.

Vulnerable Packages/Systems:

Netscape Certificate Management System 4.2 (Microsoft Windows NT 4.0 version)
Netscape Directory Server 4.12 (Microsoft NT 4.0 version)

Solution/Vendor Information/Workaround:

Contact the vendor for a fix. Patches for iPlanet products are usually available from:

Additionally, advisories and information on security issues of these particular Netscape products can be obtained from:

iPlanet Certificate Management System

Netscape Directory Server

Vendor notified on: October 2nd, 2000

Last contact with the vendor was on October 18th, 2000 when CORE SDI was informed that a patch for a problem reported previously was available and that information and a status report for the vulnerability described in this advisory would be available later that day.

Since then no communication from the vendor was received, even after two emails asking for an update on October 23rd. and October 30th.


This vulnerability was found by Emiliano Kargieman and Agustin Kato Azubel from Core SDI S.A.

This advisory was drafted with the help of the Vulnerability Help Team. For more information or assistance drafting advisories please mail


Technical Description - Exploit/Concept Code:

The Netscape Directory Server 4.12 provides a Web to LDAP gateway, by means of the Directory Services Gateway (DSGW) web server.

No authentication credentials are required from the client to access DSGW.

The same service is installed and used as part of the Certificate Management
System (Netscape/iPlanet CMS 4.2) and in this case it listens on a tcp port chosen during the installation process (24326/tcp in this example).

A request with an URI as follows:
will trigger an exception at 0x00403c62 and cause the server to hang and stop servicing requests until the exception generated is dismissed.

The same problem is present in all the binaries in the Netscape\Server4\dsgw\bin directory (auth,csearch,dnedit,doauth, domodify,dosearch,edit,lang,newentry,search,unauth), except for the program 'tutor'.

The '%' can be replaced by any string with a non-alphanumeric character in it, except for '_' and '-'. The string length doesn't matter in this specific problem, as shown in the example above, a string of just one non-alphanumeric character is enough.

The problem lies in a function that uses a buffer that is allocated if the string after 'context=' is alphanumeric, but isn't if the string is non-alphanumeric.

The contents of this advisory are copyright (c) 2000 CORE SDI S.A. and may be distributed freely provided that no fee is charged for this distribution and proper credit is given.