From labs-no-reply@idefense.com Tue May 24 17:10:29 2005 From: iDEFENSE Labs To: bugtraq@securityfocus.com, vulnwatch@vulnwatch.org, full-disclosure@lists.grok.org.uk Date: Tue, 24 May 2005 16:09:16 -0400 Subject: iDEFENSE Security Advisory 05.24.05: Ipswitch IMail IMAP LSUB DoS Vulnerability Ipswitch IMail IMAP LSUB DoS Vulnerability iDEFENSE Security Advisory 05.24.05 www.idefense.com/application/poi/display?id=245&type=vulnerabilities May 24, 2005 I. BACKGROUND Ipswitch Collaboration Suite (ICS) is a comprehensive communication and collaboration solution for Microsoft Windows with a customer base of over 53 million users. More information is available on the vendor's website: http://www.ipswitch.com/products/IMail_Server/index.html II. DESCRIPTION Remote exploitation of a denial of service (DoS) vulnerability in Ipswitch Inc.'s IMail IMAP daemon allows attackers to cause 100 percent CPU use on the server, thereby preventing legitimate users from retrieving e-mail. The problem specifically exists within IMAPD32.EXE upon parsing a malformed LSUB command. An attacker can cause the daemon to produce heavy load by transmitting a long string of NULL characters to the 'LSUB' IMAP directive. This, in turn, causes an infinite loop, eventually exhausting all available system resources and causing a denial of service. III. ANALYSIS Exploitation allows unauthenticated remote attackers to render the IMAP server useless, thereby preventing legitimate users from retrieving e- mail. This attack takes few resources to launch and can be repeated to ensure that an unpatched system is unable to recover. Exploitation requires a valid IMAP account, thus limiting the impact of this vulnerability. IV. DETECTION iDEFENSE has confirmed the existence of this vulnerability in Ipswitch IMail version 8.13. It is suspected that earlier versions are also vulnerable. V. WORKAROUND As this vulnerability is exploited after authentication occurs, ensuring that only trusted users have accounts can mitigate the risk somwhat. As a more effective workaround, consider limiting access to the IMAP server by filtering TCP port 143. If possible, consider disabling IMAP and forcing users to use POP3. VI. VENDOR RESPONSE The vendor has released the following patch to fix this vulnerability: ftp://ftp.ipswitch.com/Ipswitch/Product_Support/IMail/imail82hf2.exe The associated vendor advisory can be found at: http://www.ipswitch.com/support/imail/releases/imail_professional/im82hf 2.html VII. CVE INFORMATION The Common Vulnerabilities and Exposures (CVE) project has assigned the name CAN-2005-1249 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 04/25/2005 Initial vendor notification 05/10/2005 Initial vendor response 05/24/2005 Public disclosure IX. CREDIT The discoverer of the first vulnerability wishes to remain anonymous. Get paid for vulnerability research http://www.idefense.com/poi/teams/vcp.jsp Free tools, research and upcoming events http://labs.idefense.com X. LEGAL NOTICES Copyright (c) 2005 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 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.