Novell eDirectory NCP Fragment Denial of Service Vulnerability iDefense Security Advisory 04.26.07 http://labs.idefense.com/intelligence/vulnerabilities/ Apr 26, 2007 I. BACKGROUND Novell eDirectory is a cross-platform lightweight directory access protocol (LDAP) server. In addition to LDAP, eDirectory also implements NCP over IP. More information can be found on Novell's web site at the following URL. http://www.novell.com/products/edirectory/ II. 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 within the NCP functionality of eDirectory. Sending a sequence of specially crafted fragmented requests will cause a DoS condition. If the input is crafted properly, eDirectory will report to its error log that a fragment has been received with an invalid length. The error message includes the contents of the fragments in hexadecimal notation. However, if the length is negative, eDirectory will try to dump data to the log indefinitely. This results in a large amount of data being saved to the log. Once the end of the heap segment is reached, a memory access violation will occur and the server process will crash. III. ANALYSIS Successful exploitation of this vulnerability could allow an attacker to crash the server process. No credentials are required. Repeated attacks could allow the attacker to cause excessive disk space usage. IV. DETECTION iDefense has confirmed the existence of this vulnerability in version 8.8.1 of Novell Inc.'s eDirectory server with FTF1 applied. The earliest version tested was 8.8. Earlier versions are suspected to be vulnerable. V. WORKAROUND iDefense is unaware of any effective workaround for this issue. VI. VENDOR RESPONSE Novell has addressed this problem within FTF2 for eDirectory 8.8.1. More information is available in Novell Document ID 3924657 at the following URL. http://www.novell.com/support/search.do?cmd=displayKC&docType=kc&externalId=3924657&sliceId=SAL_Public VII. CVE INFORMATION The Common Vulnerabilities and Exposures (CVE) project has assigned the name CVE-2006-4520 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 08/17/2006 Initial vendor notification 08/18/2006 Initial vendor response 10/21/2006 Second vendor notification 10/23/2006 Vendor response 12/06/2006 Third vendor notification 12/18/2006 Vendor response 03/21/2007 Fourth vendor notification 04/25/2007 Fifth vendor notification 04/25/2007 Vendor advised that the fix was in FTF2 04/26/2007 Coordinated public disclosure IX. CREDIT The discoverer of this vulnerability wishes to remain anonymous. Get paid for vulnerability research http://labs.idefense.com/methodology/vulnerability/vcp.php Free tools, research and upcoming events http://labs.idefense.com/ X. LEGAL NOTICES Copyright © 2007 iDefense, 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 e-mail customerservice@private 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.
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