TO UNSUBSCRIBE: email "unsubscribe alert" in the body of your message to majordomo@iss.net Contact alert-owner@iss.net for help with any problems! --------------------------------------------------------------------------- -----BEGIN PGP SIGNED MESSAGE----- Internet Security Systems Security Alert March 14, 2001 "Stick"- A Potential Denial of Service Against IDS Systems Synopsis: ISS X-Force has been researching a new attack tool that can be used to launch a stress test against many popular intrusion detection systems (IDS). The new tool, dubbed "Stick" by its creators, has been reported to reduce performance, and/or deny service to many commercial IDS products. Stick has been reported to direct thousands of overt attacks at IDS systems. The additional processing required by IDS systems to handle the new load causes a Denial of Service (DoS) to manifest. Description: Stick does not employ any new methods, nor does it expose any new flaws in signature-based IDS. Stick uses the very straightforward technique of firing numerous attacks at random from random source IP addresses to purposely trigger IDS events. The IDS system will attempt to keep up with the new flood of events, but if incoming events cross the IDS detection threshold, a DoS might result. The effectiveness of the Stick attack is a function of the attacker's available bandwidth. Stick is essentially a flooding tool, so if a large bandwidth link is available to the attacker, he or she may be more successful. At the time of publication of this Alert, the Stick tool has not been made public. Refer to the following URL for more information about the attack: . ISS X-Force verified the existence of the vulnerability in the Windows NT and Windows 2000 versions of RealSecure Network Sensor 5.0. On both Windows platforms, the event channel becomes congested during the duration of the attack. The Network Sensor must be manually reconnected to restore normal operation. At no point does the Network Sensor or Network Console crash. RealSecure running on the Solaris platform does not exhibit any event channel problems during the attack or after the attack is suspended. No reconnection is required. Recommendations: ISS X-Force has developed two fixes for RealSecure Network Sensor that will limit the risk of a Stick attack. The first fix was part of Service Release 1.1 for RealSecure Network Sensor. The second fix will be included in X-Press Update MU 2.2, available on March 15, 2001. X-Press Update MU 2.2 will also include 28 new signatures and can be accessed through the Internet Security Systems Web site at: . About Internet Security Systems (ISS) Internet Security Systems is the leading global provider of security management solutions for the Internet, protecting digital assets and ensuring safe and uninterrupted e-business. With its industry-leading intrusion detection and vulnerability assessment, remote managed security services, and strategic consulting and education offerings, ISS is a trusted security provider to more than 8,000 customers worldwide including 21 of the 25 largest U.S. commercial banks and the top 10 U.S. telecommunications companies. Founded in 1994, ISS is headquartered in Atlanta, GA, with additional offices throughout North America and international operations in Asia, Australia, Europe, Latin America and the Middle East. For more information, visit the Internet Security Systems web site at www.iss.net or call 888-901-7477. Copyright (c) 2001 Internet Security Systems, Inc. Permission is hereby granted for the redistribution of this Alert electronically. It is not to be edited in any way without express consent of the X-Force. If you wish to reprint the whole or any part of this Alert in any other medium excluding electronic medium, please e-mail xforce@iss.net for permission. Disclaimer The information within this paper may change without notice. Use of this information constitutes acceptance for use in an AS IS condition. There are NO warranties with regard to this information. In no event shall the author be liable for any damages whatsoever arising out of or in connection with the use or spread of this information. Any use of this information is at the user's own risk. X-Force PGP Key available at: as well as on MIT's PGP key server and PGP.com's key server. Please send suggestions, updates, and comments to: X-Force xforce@iss.net of Internet Security Systems, Inc. -----BEGIN PGP SIGNATURE----- Version: 2.6.3a Charset: noconv iQCVAwUBOrAI/jRfJiV99eG9AQGwDwQAmIWy56iE4OENgjzibszNaGXgE3+ixrZH FcInERGe6oqjQBkLHnKQUeEL7xzUsWNhyJpqdWOMpNuXnQhtFVyDA2zrjftwzeGt ok03rUf+9jP4EFU4mYI7DBZrUQ6mHVjms83CFJb8SPDXJLspVAPc2MsYjyZ+e44I JtE754RoW3s= =+q73 -----END PGP SIGNATURE-----