Tim- Thank you for you message. We feel that we did categorize the full scope of the vulnerability in our advisory. The exploit can be delivered to a Snort installation in "stealth" mode just as easily as any other. The fundamental difference between an IDS in normal mode vs. stealth mode is the fact that the box has no fully functioning network interface with no IP address assigned. This situation could easily be remedied by specific shellcode to detect this condition and bring up an interface. Or, shellcode could be included to destroy the filesystem, or crash the sensor. We felt that since the net effect of these types of attacks would be same regardless of how the sensor was configured, it shouldn't be described as a method to avoid exploitation and compromise.
We also felt that the most serious risk posed by this vulnerability is if an exploit was mated with a high-speed scanner designed to fire exploit packets at networks indiscriminately. These types of attacks are very successful in locating vulnerable servers, and are used everyday by Web-defacement hacking groups. This type of attack would effect every Snort sensor in its path, including stealth installations and Snort installations that were not in promiscuous mode. Regards, ============================= Dan Ingevaldson Team Lead, X-Force R&D [EMAIL PROTECTED] 404-236-3160 Internet Security Systems, Inc. The Power to Protect http://www.iss.net ============================= -----Original Message----- From: Slighter, Tim [mailto:[EMAIL PROTECTED] Sent: Monday, March 03, 2003 3:35 PM To: ISS XForce; [EMAIL PROTECTED] Subject: RE: [ISSForum] ISS Security Brief: Snort RPC Preprocessing Vulnerability Can someone from XForce please take the time to consider all aspects of this recently announced exploit? For example, organizations that have configured snort to run on a "stealth" interface only should not be impacted under any circumstances and therefore should not impetuously scramble to download and deploy the latest build. For example: The section "It is also not necessary to know the network location of a Snort sensor. Exploit packets can be sent to any portion of a network upon which a target Snort sensor is listening" "A successful attack can either crash the Snort sensor, or lead to complete remote compromise." Understandably this can potentially crash the snort daemon, cause the system to hang, or in a best case scenario generate a genuine buffer overflow and thereby render the system open to arbritary code. However, providing the intruder crafts a framgemented RPC packet and targets this at any asset on the known network where there also happens to be snort IDS system running in stealth mode. What possible advantage can the intruder have on following up with a attempting to take control of the compromised snort system? Additionally if snort if running in non-promiscuous mode, what are the possiblities of the intruder obtaining and highjacking a layer 2 address from the snort system? It may be advantageous to inform the public about the full scope of this exploit as well as any potential restrictions or drawbacks. Thanks Tim Slighter -----Original Message----- From: X-Force [mailto:[EMAIL PROTECTED] Sent: Monday, March 03, 2003 10:50 AM To: [EMAIL PROTECTED] Subject: [ISSForum] ISS Security Brief: Snort RPC Preprocessing Vulnerability -----BEGIN PGP SIGNED MESSAGE----- Internet Security Systems Security Brief March 3, 2003 Snort RPC Preprocessing Vulnerability Synopsis: ISS X-Force has discovered a remotely exploitable buffer overflow condition in Snort. Snort is an open source intrusion detection system. A buffer overflow flaw exists in Snort RPC preprocessing code that is vulnerable to attack. Impact: Remote attackers may exploit the buffer overflow condition to run arbitrary code on a Snort sensor with the privileges of the Snort IDS process, which typically runs as the superuser. The vulnerable preprocessor is enabled by default. It is not necessary to establish an actual connection to a RPC portmapper service to exploit this vulnerability. Snort may be installed by default on some commercially available network- security appliances. Remote attackers can exploit this vulnerability by directing the exploit towards any host on any network monitored by the Snort intrusion detection system. A successful attack can either crash the Snort sensor, or lead to complete remote compromise. Affected Versions: Snort 1.8 (July 2001) up to and including Snort-Current (March 3, 2003 1pm ET) For the complete ISS X-Force Security Advisory, please visit: http://www.iss.net/issEn/delivery/xforce/alertdetail.jsp?oid=21951 ______ About Internet Security Systems (ISS) Founded in 1994, Internet Security Systems (ISS) (Nasdaq: ISSX) is a pioneer and world leader in software and services that protect critical online resources from an ever-changing spectrum of threats and misuse. Internet Security Systems is headquartered in Atlanta, GA, with additional operations throughout the Americas, Asia, Australia, Europe and the Middle East. Copyright (c) 2003 Internet Security Systems, Inc. All rights reserved worldwide. Permission is hereby granted for the electronic redistribution of this document. It is not to be edited or altered in any way without the express written consent of the Internet Security Systems X-Force. If you wish to reprint the whole or any part of this document in any other medium excluding electronic media, please email [EMAIL PROTECTED] 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, implied or otherwise, with regard to this information or its use. Any use of this information is at the user's risk. In no event shall the author/distributor (Internet Security Systems X-Force) be held liable for any damages whatsoever arising out of or in connection with the use or spread of this information. X-Force PGP Key available on MIT's PGP key server and PGP.com's key server, as well as at http://www.iss.net/security_center/sensitive.php Please send suggestions, updates, and comments to: X-Force [EMAIL PROTECTED] of Internet Security Systems, Inc. -----BEGIN PGP SIGNATURE----- Version: 2.6.2 iQCVAwUBPmOVhDRfJiV99eG9AQEwngP/fVMwf9Cfkcwmzxme2IERb+WgNDYQIpgE 1W5ThC5s+KVkrHJGQDF4p1t+Ex2T4EmUSEC86Yx8TDi0t+zWRI0IUKrnWmOkBZQe 1a5Rn3wqqqEPQF2seK7CLxEH649Nnbt1rEr0/puclvE1XufVxjVihzkRLMErIF0h Uwpa23ETicc= =11YN -----END PGP SIGNATURE----- _______________________________________________ ISSForum mailing list [EMAIL PROTECTED] TO UNSUBSCRIBE OR CHANGE YOUR SUBSCRIPTION, go to https://atla-mm1.iss.net/mailman/listinfo _______________________________________________ ISSForum mailing list [EMAIL PROTECTED] TO UNSUBSCRIBE OR CHANGE YOUR SUBSCRIPTION, go to https://atla-mm1.iss.net/mailman/listinfo _______________________________________________ ISSForum mailing list [EMAIL PROTECTED] TO UNSUBSCRIBE OR CHANGE YOUR SUBSCRIPTION, go to https://atla-mm1.iss.net/mailman/listinfo
