IDS mailing list archives
RE: True definition of Intrusion Prevention
From: <Fengmin_Gong () NAI com>
Date: Fri, 2 Jan 2004 18:34:19 -0800
Mark, Thanks for the feedback. You are absolutely correct that getting the prevention system tuned to the particular network it's deployed is a real critical factor. Today what you have on the one hand, is some capability for correlating the host and vulnerability identification with IDS alert, such those from Tenable or RNA; on the other hand, you have system with inline blocking capability like I1200/2600/4000. What you would ideally want is to have these capability integrated in one system. The language underlying Intrushield does recognize things like applicable software packages, versions, or protocols for any given vulnerability. But there is currently no ready interface for taking the vulnerability scanner info to customize the policy for your environment automatically. We are fully aware of such needs and working towards such capability. So, that's why currently serious prevention users are expected to deploy the solution in inline but in monitoring mode (IDS) initially, to account for environmental behaviors, and to tune out false-positive prone events before transition to enable blocking. With no intention to start a "what's anomaly detection" debate, let me add a few words related to dealing with zero-day exploits. Let's consider only buffer overflow kind of attacks for a moment, considering that these are still by far the most dangerous ones today. If a vulnerability is known, we can write a very reliable set of checks (note that I am avoiding using signature or anomaly because they are not always as clearly understood as people like; the checks I refer to can be a combination of multiple string matches, length check of very specific fields/subfields, and scan for generic shellcode segments) to detect all variants of the exploit against this vulnerability. So what can we do to deal with potential zero-day exploits? We all know that one way to catch potential buffer overflow is using length checks. Equipped with stream reassembly and protocol parsing, we can define length checks for a lot of fields even though there is no reported vulnerability. However, it's very challenging to get some of these thresholds right especially when there are multiple implementations that can interpret these fields, and the usage varies from environment to environment. This kind of capability is useful for environments where very critical assets are being protected, and skilled security analysts are available to closely monitor and tune the policies. You may be spending 95% of extra effort to obtain 5% of extra coverage, in order to comfortably consider enabling blocking on these events. Another way to provide less aggressive coverage for zero-day exploit but offering more reliable detection is through detection of shellcode in specific application fields. Here we are not talking about some simple noop sequence match or other opcode match, rather a fairly comprehensive shellcode profile match. This detection has been found to be very reliable to warrant blocking without much concern. This event is also sufficiently malicious across all deployment environments. Of course, some buffer overflow without shellcode may slip through to cause DoS on the target, but that is the tradeoff the user needs to make. These capabilities are indeed very powerful, and takes some effort to utilize them fully. We are constantly exploring ways to make the configuration of these capabilities more flexible so that users can get the most benefit with less tuning effort. Please feel free to send all suggestions to me directly so that we do not take up other folks' bandwidth on the list. Regards, Fengmin -----Original Message----- From: Teicher, Mark (Mark) [mailto:teicher () avaya com] Sent: Friday, January 02, 2004 4:43 PM To: Gong, Fengmin; gwc () acm org; flynngn () jmu edu Cc: focus-ids () securityfocus com Subject: RE: True definition of Intrusion Prevention Fengmin, Thank you for your reply. The real teeth behind any Intrusion Prevention system is for the system to understand the particular network it is deployed in. As I just completed a very thorough product evaluation of the I-2600 appliance in a particular network environment. It detected lots of attacks that were more or less false positives due to the nature of the network traffic generated. Remediation steps will vary enterprise to enterprise. I found that one can sandbox attacks to see how the attacks operate instead of out and out denying the traffic. There has not been one IPS available that really does a good job on zero day exploits. Although zero day exploits are very hard to predict unless one is doing throwing some processor power into the protocol dis-assembly re-assembly. Another point to illustrate is that most IPS systems today do not have true IPS type attacks, except for a few modified IDS signatures with TCP shunning abilities. Classifications of IPS signatures can also be overwhelming. Categorizations and granularity becomes an exercise in futility. Bulk Editing of learned actions is interesting, but not intuitive.. /hope that confuses the issue more. /cheers P.S. Still waiting for Al H to reply.. :) /mark -----Original Message----- From: Fengmin_Gong () NAI com [mailto:Fengmin_Gong () NAI com] Sent: Friday, January 02, 2004 5:29 PM To: gwc () acm org; Teicher, Mark (Mark); flynngn () jmu edu Cc: focus-ids () securityfocus com Subject: RE: True definition of Intrusion Prevention Hi All, Ron Gula and George Capehart etc. have made many good points about the current state of confusion facing customers surrounding "intrusion prevention". I agree with the overall comments. I do have a slightly different take on the interpretation of "intrusion prevention" and on how customers as a whole can better deal with the current situation. Before I offer my personal perspective, I do want to let you all know that I am with NAI as part of the IntruVert acquisition and I was one of the key people behind the technology, although I will be staying focused on the IPS perspective. "Intrusion prevention" can be achieved through three main approaches: (1) secure engineering - to build system with no vulnerability and use it with perfect practice, (2) taking perfect remediation steps to uncover vulnerabilities and patch them before the attackers, and (3) detecting the exploit attempts (i.e. attacks) and blocking them before serious damage is done. Note that all three approaches are not mutually exclusive. Secure engineering has been a research area for many years, it's still not clear how practical it can get and when. Remediation should be pursued in all environments possible, but it cannot be an end-all solution either due to difficulties with automated deployment and the diverse vulnerabilities that can be exploited without us knowing them. I refer to (3) as the most practical "intrusion prevention" today - detection with real-time blocking. Most noticeable example will be shellcode execution detection and dropping the payload in the network or preventing execution in the end hosts. As pointed out earlier by Ron, firewall would have achieved adequate prevention as well if a narrow enough rule can be defined that blocks the delivery of a particular attack payload. The main issue is that, today's firewall as we know it, does not offer the granularity to differentiate a normal instance of application session from one that is delivering the attack. From this perspective, prevention is a natural new capability available from newer IDS technologies. Depending on the deployment environments, IDS as we know it - monitoring only, will continue to play an important role in implementing security policies. With inline blocking capability (IPS as interpreted in this context), we now have a much more effective policy enforcement tool. By the same reasoning, customers in general will be better off if they do a little more due diligence - to see beyond the acronyms. So it's OK that marketing has forced IPS upon us without a clear definition. If you ask question and assess exactly how particular attack conditions are detected, what actions can be taken - manual or automatic, what really happens when a particular action is taken, etc., you are in a better position to make right decisions for your needs. Have a great new year! Fengmin -- Fengmin Gong, D.Sc. Chief Scientist McAfee Network Security Network Associates fengmin_gong () nai com 408-346-3237 -----Original Message----- From: George Capehart [mailto:gwc () acm org] Sent: Friday, January 02, 2004 7:57 AM To: Teicher, Mark (Mark); Gary Flynn Cc: focus-ids () securityfocus com Subject: Re: True definition of Intrusion Prevention On Friday 02 January 2004 09:41 am, Teicher, Mark (Mark) wrote:
<comments within>
<snip>
<Yes, that was the point, that marketing type people have blinded me with their definition, that I am completely confused and dumbfounded>
*grin* Well, then, I guess that disqualifies you from being a Gartner-reading pointy-haired manager . . . ;-> <snip>
<Prevention, my mother always told me always use "protection", but to this day, I am not quite sure what she meant>\
Heh. My dad used to tell me the same thing . . . but he made *really* sure that I knew what he meant. *wince* <snip>
<The term "Intrusion Prevention" isn't clearly defined, as you have observed, but "Intrusion Blocking" doesn't ring the ears like the marketing folks what you to do"
Ah, yes! *Now* I'm beginning to understand . . .
Don't get me wrong, I don't have a problem with "intrusion blocking" if it is successful . . . that is, if the attack is detected in time and the appropriate "blocking mechanisms" are available. I'd just rather call a duck a duck . . . ;-) I think it is possible to build an "intrusion blocking device." Intrusion prevention is a process. (Apologies to Bruce Schneier ;-) ) <"Intrusion Prevention is a process??" What kind of blocking mechanisms are you referring to ?? I have never met a duck who dabbles in information security, I have heard of a cat who swipes at their owner when they program insecure code :)>
What I really had in mind when I said that was that, to me at least, if there really could be such a thing as Intrusion Prevention (TM), that sort of implies staying ahead of the attacker. That is a process. One of the tools the process could/would use is "intrusion blocking." Another thing the process would/could do is design and build systems that don't have weaknesses that could be exploited in intrusion attacks. Another is to neutralize the attackers before they attack. *All* of this, though is a process. Preventing an intrusion by blocking implies understanding the vulnerabilities of the system, the corresponding attack vectors and putting layers of defense in place that will either block outright or "defang" the attack. But the world isn't static, new vulnerabilities are exposed and new attacks are concocted daily. Staying on top of them takes constant effort and implementing defenses and installing patches is an ongoing process. This is why I feel that Intrusion Prevention (TM) is a process . . . <snip>
<what distinction?? The marketing folks created a term that no one in
the industry understands. Blocking is often referring to as TCP Shunning, but since this the New Year's day, why not start the year off without falling off the soapbox :)>
*snicker* *snicker* *guffaw* *guffaw* /g BTW, a happy and prosperous New Year to all. ------------------------------------------------------------------------ --- ------------------------------------------------------------------------ --- --------------------------------------------------------------------------- ---------------------------------------------------------------------------
Current thread:
- Re: True definition of Intrusion Prevention, (continued)
- Re: True definition of Intrusion Prevention George Capehart (Jan 05)
- RE: True definition of Intrusion Prevention Teicher, Mark (Mark) (Jan 02)
- Re: True definition of Intrusion Prevention George Capehart (Jan 02)
- RE: True definition of Intrusion Prevention Brian Taylor (Jan 05)
- Re: True definition of Intrusion Prevention Gary Flynn (Jan 05)
- Re: True definition of Intrusion Prevention George Capehart (Jan 02)
- RE: True definition of Intrusion Prevention Teicher, Mark (Mark) (Jan 05)
- RE: True definition of Intrusion Prevention Bohling James CONT JBC (Jan 05)
- RE: True definition of Intrusion Prevention Teicher, Mark (Mark) (Jan 05)
- Re: True definition of Intrusion Prevention George Capehart (Jan 05)
- RE: True definition of Intrusion Prevention Teicher, Mark (Mark) (Jan 05)
- RE: True definition of Intrusion Prevention Fengmin_Gong (Jan 05)
- RE: True definition of Intrusion Prevention Fengmin_Gong (Jan 05)
- RE: True definition of Intrusion Prevention Teicher, Mark (Mark) (Jan 05)
- Re: True definition of Intrusion Prevention George Capehart (Jan 05)
- Re: True definition of Intrusion Prevention Frank Knobbe (Jan 05)
- Re: True definition of Intrusion Prevention George Capehart (Jan 05)
- RE: True definition of Intrusion Prevention Bohling James CONT JBC (Jan 05)
- Re: True definition of Intrusion Prevention George Capehart (Jan 05)
- RE: True definition of Intrusion Prevention Vigilant Labs (Jan 07)
- Re: True definition of Intrusion Prevention George Capehart (Jan 07)
- Re: True definition of Intrusion Prevention Andrew Plato (Jan 08)