-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 =============================================================================== >> CERT-NL, 01-Mar-2000 << >> All CERT-NL information has been moved to http://cert.surfnet.nl. Links << >> to CERT-NL information contained in this advisory are therefore outdated. << >> << >> CERT-NL also has stopped the CERT-CC-Mirror service. Due to this the << >> links to the CERT-CC mirror are obsolete. Visit the CERT-CC site for the << >> complete CERT-CC advisory texts: http://www.cert.org << =============================================================================== =============================================================================== Security Advisory CERT-NL =============================================================================== Author/Source : Teun Nijssen Index : S-00-02 Distribution : World Page : 1 Classification: External Version: 1 Subject : Denial of Service mit Stacheldraht Date :04-Jan-2000 =============================================================================== By courtesy of the CERT Coordination Center and the Federal Computer Incident Response Capability (FedCIRC) we received info on new developments in denial-of-service tools. Note that the info in this advisory is related to CERT-NL advisory S-99-52. The use of the irresistable word Stacheldraht, the wide scope of the advisory and the newly included URLs however motivated a new advisory. ______________________________________________________________________ CERT Advisory CA-2000-01 Denial-of-Service Developments Systems Affected * All systems connected to the Internet can be affected by denial-of-service attacks. I. Description Continued Reports of Denial-of-Service Problems We continue to receive reports of new developments in denial-of-service tools. This advisory provides pointers to documents discussing some of the more recent attacks and methods to detect some of the tools currently in use. Many of the denial-of-service tools currently in use depend on the ability of an intruder to compromise systems first. That is, intruders exploit known vulnerabilities to gain access to systems, which they then use to launch further attacks. For information on how to protect your systems, see the solution section below. Security is a community effort that requires diligence and cooperation from all sites on the Internet. Recent Denial-of-Service Tools and Developments One recent report can be found in CERT Advisory CA-99-17. A distributed denial-of-service tool called "Stacheldraht" has been discovered on multiple compromised hosts at several organizations. In addition, one organization reported what appears to be more than 100 different connections to various Stacheldraht agents. At the present time, we have not been able to confirm that these are connections to Stacheldraht agents, though they are consistent with an analysis provided by Dave Dittrich of the University of Washington, available at http://staff.washington.edu/dittrich/misc/stacheldraht.analysis Also, Randy Marchany of Virginia Tech released an analysis of a TFN-like toolkit, available at http://www.sans.org/y2k/TFN_toolkit.htm The ISS X-Force Security Research Team published information about trin00 and TFN in their December 7 Advisory, available at http://xforce.iss.net/alerts/advise40.php3 A general discussion of denial-of-service attacks can be found in a CERT/CC Tech Tip available at http://www.cert.org/tech_tips/denial_of_service.html II. Impact Denial-of-service attacks can severely limit the ability of an organization to conduct normal business on the Internet. III. Solution Solutions to this problem fall into a variety of categories. Awareness We urge all sites on the Internet to be aware of the problems presented by denial-of-service attacks. In particular, keep the following points in mind: * Security on the Internet is a community effort. Your security depends on the overall security of the Internet in general. Likewise, your security (or lack thereof) can cause serious harm to others, even if intruders do no direct harm to your organization. Similarly, machines that are not part of centralized computing facilities and that may be managed by novice or part-time system administrators or may be unmanaged, can be used by intruders to inflict harm on others, even if those systems have no strategic value to your organization. * Systems used by intruders to execute denial-of-service attacks are often compromised via well-known vulnerabilities. Keep up-to-date with patches and workarounds on all systems. * Intruders often use source-address spoofing to conceal their location when executing denial-of-service attacks. We urge all sites to implement ingress filtering to reduce source address spoofing on as many routers as possible. For more information, see RFC2267. * Because your security is dependent on the overall security of the Internet, we urge you to consider the effects of an extended network or system outage and make appropriate contingency plans where possible. * Responding to a denial-of-service attack may require the cooperation of multiple parties. We urge all sites to develop the relationships and capabilities described in the results of our recent workshop before you are a victim of a distributed denial-of-service attack. This document is available at http://www.cert.org/reports/dsit_workshop.pdf Detection A variety of tools are available to detect, eliminate, and analyze distributed denial-of-service tools that may be installed on your network. The National Infrastructure Protection Center has recently announced a tool to detect trin00 and TFN on some systems. For more information, see http://www.fbi.gov/nipc/trinoo.htm Part of the analysis done by Dave Dittrich includes a Perl script named gag which can be used to detect stacheldraht agents running on your local network. See Appendix A of that analysis for more information. Internet Security Systems released updates to some of their tools to aid sites in detecting trin00 and TFN. For more information, see http://www.iss.net/cgi-bin/dbt-display.exe/db_data/press_rel/release/1 22899199.plt Prevention We urge all sites to follow sound security practices on all Internet-connected systems. For helpful information, please see http://www.cert.org/security-improvement http://www.sans.org Response For information on responding to intrusions when they do occur, please see http://www.cert.org/nav/recovering.html http://www.sans.org/newlook/publications/incident_handling.htm The United States Federal Bureau of Investigation is conducting criminal investigations involving TFN where systems appears to have been compromised. U.S. recipients are encouraged to contact their local FBI Office. _________________________________________________________________ We thank Dave Dittrich of the University of Washington, Randy Marchany of Virginia Tech, Internet Security systems, UUNet, the Y2K-ICC, the National Infrastructure Protection Center, Alan Paller and Steve Northcutt of The SANS Institute, The MITRE Corporation, Jeff Schiller of The Massachusetts Institute of Technology, Jim Ellis of Sun Microsystems, Vern Paxson of Lawrence Berkeley National Lab, and Richard Forno of Network Solutions. ______________________________________________________________________ This document is available from: http://www.cert.org/advisories/CA-2000-01.html ============================================================================== CERT-NL is the Computer Emergency Response Team for SURFnet customers. SURFnet is the Dutch network for educational, research and related institutes. CERT-NL is a member of the Forum of Incident Response and Security Teams (FIRST). All CERT-NL material is available under: http://cert.surfnet.nl/ In case of computer or network security problems please contact your local CERT/security-team or CERT-NL (if your institute is NOT a SURFnet customer please address the appropriate (local) CERT/security-team). CERT-NL is one/two hour(s) ahead of UTC (GMT) in winter/summer, i.e. UTC+0100 in winter and UTC+0200 in summer (DST). Email: cert-nl@surfnet.nl ATTENDED REGULARLY ALL DAYS Phone: +31 302 305 305 BUSINESS HOURS ONLY Fax: +31 302 305 329 BUSINESS HOURS ONLY Snailmail: SURFnet bv Attn. CERT-NL P.O. Box 19035 NL - 3501 DA UTRECHT The Netherlands NOODGEVALLEN: 06 22 92 35 64 ALTIJD BEREIKBAAR EMERGENCIES : +31 6 22 92 35 64 ATTENDED AT ALL TIMES CERT-NL'S EMERGENCY PHONENUMBER IS ONLY TO BE USED IN CASE OF EMERGENCIES: THE SURFNET HELPDESK OPERATING THE EMERGENCY NUMBER HAS A *FIXED* PROCEDURE FOR DEALING WITH YOUR ALERT AND WILL IN REGULAR CASES RELAY IT TO CERT-NL IN AN APPROPRIATE MANNER. CERT-NL WILL THEN CONTACT YOU. =============================================================================== -----BEGIN PGP SIGNATURE----- Version: PGP 6.5.1i iQA/AwUBOL6IBTSYjBqwfc9jEQKb9ACgiMnLHB+kpOxAeECYJYw4o+Z4gIIAoM9Q XZil3pD6Fcw+/DQFI7otBPwY =vvST -----END PGP SIGNATURE-----