do we really need anti-virus

thanks to alan shimel for pointing out this post by kai roer asking if we need anti-virus in 2008...

alan is right, of course, that anti-virus does a lot more than just catch viruses these days, and that anti-virus helps control older virus populations (good on ya alan, most people don't consider that)... kai asked a variety of interesting questions, thouhg, which i tried to answer in his comments... like lonervamp mentions at the start of this post, discussions like this are something i'd prefer not to lose to the sands of time so i'm reposting my comments here (and i may start doing this more often, 'cause it seems like a great idea):

"Have the virus authors started to write smaller virus that stays below the radar - and thus are not detected by the AV-products?"

many of the virus authors of old have simply grown up and found more fulfilling things to do with their lives...

"Are they now only targeting special targets - like particular banks, SCADA or singled out corporations? Or countries and causes? Or are they too busy writing malware to care about virus? "

viruses are malware... non-viral malware, however, seems to be what the cyber-crooks prefer these days... self-replication has a way of getting out of hand and calling attention to the malware...

"Do we really need to pay out on gateway and client AV solutions if there are no virus knocking on the door? "

who says there isn't? just because you aren't hearing about new epidemics doesn't mean new viruses aren't getting written or even that the old ones have stopped... some of the most prevalent email-born malware are mass-mailing worms that are already a few years old (like netsky.p)...

"Do you believe that there are no more virus out there?"

absolutely not... some people are still getting infected by decades-old boot infectors...

"That other threats are taking over and rendering AV-solutions useless?"

other threats are just as detectable with av as viruses are...

"Is this the whole truth? Or have the AV solutions became so good that they catch everything, even without us noticing? That they are an absolute critical part of the solution for any entity connected to the net?"

let's put it this way - old viruses never die, their populations just shrink to a size too small to accurately report/track... av is one of the things that helps keep those populations small...

and when it comes to newer non-viral malware, av is what helps keep it's usability limited... without the blacklist, the bad guys would just find something that successfully bypassed other defenses and keep using it over and over because other defenses cannot be updated as fast as a blacklist...

the state of anti-virus

there have been some posts and discussions recently about anti-virus that i thought were interesting (and not just because my name was invoked) and rather that split my thoughts between multiple sites i've opted to combine everything here... thankfully most involved welcome open debate on the subject, though others not so much - but refusing to believe malware and vulnerabilities are orthogonal to one another kinda limits where the discussion can go, so oh well...

so i'm going to start with michael's post over at mcwresearch.com... now i hope michael doesn't take this the wrong way, but i quite enjoyed the irony of his post's title - "AV must innovate or die"... michael of course comes from a behaviour-based HIPS background and behaviour-based HIPS (or at the very least it's precursor) began it's life in an anti-virus product...

furthermore, as i've mentioned before, anti-virus isn't just blacklist-based scanners... rather it's an archaic term for anti-malware and since HIPS is itself a type of anti-malware technology, HIPS is fundamentally part of the same industry that michael is criticizing - which means he himself is making that innovation happen and making sure 'anti-virus' doesn't die...

of course, when michael used the term anti-virus, he really was just talking about known-malware scanners and criticizing them for not being able to do what is totally outside the scope of a known-malware scanner - block unauthorized behaviour... that's actually a pretty unfair criticism since he's only considering the scanner technology itself and no technology (not scanners or HIPS) is perfect, they all do different things and they all have their limitations... he's mentioned in the past that anti-virus needs to get it's peanut butter mixed in with IPS's chocolate so i'm going to give michael a treat... symantec has HIPS, mcafee has HIPS, trend micro has HIPS, sophos has HIPS, kaspersky has HIPS built into KIS, f-secure has HIPS, panda has HIPS, etc... perhaps in the future michael will consider all the technologies that traditional av vendors make available so that he doesn't have to compare apples to oranges anymore...

the other post that caught my eye was this one by lonervamp (he's also a michael but let's not get ambiguous) about where he sees the state of anti-virus being... he also refers to anti-virus in a strictly known-malware scanning context and discusses the role it's supposed to play in a defensive strategy and how it's benefits have waned with the development of procedural and technological layers that complement it's use... i would actually tend to agree with that observation, but i'd also note that being complementary is a commutative property - known-malware scanning complements those other layers as well... could you go without scanning entirely? sure, just like you could use only scanning, but they're better together than they are on their own... that the benefits of known-malware scanning wane in the presence of complementary layers is entirely understandable and expected as the layers in a multi-layered defense will generally partially overlap each other... it's because of that overlap that the benefits of any individual layer may wane, but a layer isn't redundant or useless unless it's completely overlapped by the other layers...

so a question that is perhaps of interest to both posters is at what point does known-malware scanning become entirely redundant?... personally, i don't think it ever does... any given technology has an achilles heel that can allow a piece of malware to get past it... for known-malware scanning this achilles heel is novelty - new/unknown malware is clearly not something known-malware scanning can deal with... other technologies have their own weaknesses too but as weaknesses go novelty is unique because it's the only one that wears off... the media makes quite a big deal out of all the new malware being created and how it keeps getting past known-malware scanners, and at the same time it rarely mentions cases of malware incidents involving old malware... this leads to the erroneous impression that one needn't worry about old malware... old malware still pops up for a variety of different reasons and although it may use tricks that can still allow it to get past other technologies, by the time it gets old it's not going to be getting past a known-malware scanner anymore...

lonervamp also made a distinction between home use and business use, suggesting that known-malware scanning was more likely to be displaced in the business than in the home... i can certainly see that - one of the strengths of known-malware scanning is that the expertise that makes it work is embedded in the product so that the user is relieved of having that burden... many other technologies require knowledge and skill from the customer that may or may not be there... in a business you're much more likely to have trained, knowledgeable individuals (the IT staff) who can make the intelligent decisions necessary for products with more client side configuration to work effectively... that means that alternative technologies become a more feasible option in that environment...

that isn't to say i'd suggest dropping known-malware scanning though... even in a business i think it has it's place... i don't think it should be the only type of technology used, mind you - there are many types of technology available (sometimes even from a single vendor) and they're just waiting to be used... if i were going to suggest anything it would be more comprehensive layering, not simply different layers... the goal should be better overall coverage and substituting one layer for another isn't necessarily the way to get there...

why X is insecure - and probably always will be

about 2 weeks ago (old i know) you may have come across these two articles (by drazen drazic and lonervamp respectively) about why businesses are insecure (the 7 reasons why businesses are insecure and more reasons why businesses are insecure)...

i'm sure they're very good business reasons for why businesses are insecure, but i'm also sure that a business that addressed all of these problems would still be insecure for reasons that have nothing to do with that business or businesses in general or business security in general...

the fact is there's a technical reason why virtually any non-trivial thing (of which anything computer related would definitely fall under) we'd want to secure is almost certainly not secure and probably never will be... i'm not talking about the fact that there is no such thing as secure, rather i'm talking about the asymmetric relationship between attack and defense... if you're trying to defend something you have to try to defend it from all possible attacks, but if you're trying to attack something you only need to find one successful attack vector...

clearly defense takes a lot more work and that's a problem, but it's not clear that we can ever really change that... if we were going to try to change it, though, how would we go about it? the two obvious answers are: 1) make defense easier (presumably by reducing the amount of possible attacks we need to defend against), or 2) make finding that one successful attack vector harder...

making defense easier sounds good but it's easier said than done... sun tzu talked about this very thing when he said that one should force the enemy to engage in an environment of one's own choosing and thus choose what one has to defend and what the enemy can attack (art of war, part 6: weak points and strong)... now you might be tempted to limit the scope of your analysis to an arbitrarily narrow frame of reference (as schneier does here when he refers to cryptography to the exception to the rule of asymmetry between attack and defense) but in reality that doesn't actually get us any closer to our goal of reducing the amount of defenses we need... what we would really need to do is reduce the pool of potential attack vectors, to literally remove things from systems that could be used as an avenue of attack... that means fewer hosts on our networks, less diversity amongst the hosts on our networks (gasp! yes, i said it - diversity is great for minimizing the overall effect a successful attack has on a given population of hosts but it increases the pool of potential attack vectors and so makes compromising assets on the network easier; in essence, what's good for availability may not be so good for confidentiality), fewer services running on those hosts, fewer system components exposed to incoming content (ie. browsers, email clients and other network clients/servers that can do less/have less functionality), less potentially sensitive data stored on those hosts, etc... unfortunately this is completely backwards when viewed through the lens of technological progress, and while minor efforts in this area are no doubt considered beneficial, it would take extreme measures (perhaps even beyond the realm of the realistic given the complexity of modern operating systems) to actually make a significant change in the asymmetry between attack and defense for a system...

making it harder to find that one successful attack vector isn't necessarily a piece of cake either... there's one fairly well known school of thought that posits that reducing the number of vulnerabilities will shrink the pool of potentially successful attack vectors... this school of thought may be right, in a theoretical sense, but in practice it's starting to look like the total number of vulnerabilities is high enough that patching vulnerabilities at the rate we're going right now isn't really having that big an impact on the difficulty of finding a successful attack vector... another well known approach is to devise a system where the attacker has to successfully defeat multiple defenses in order to be successful on the whole... this is, of course, defense in depth... naively one might think this could put attacker and defender on more or less equal footing because now not only does the defender have to defend against a large number of possible attacks, the attacker has to breach a large number of possible defenses... unfortunately, there are only so many defenses one can reasonably deploy and, even with all of them deployed, the amount of work an attacker has to do still won't compare to the amount of work required for defense - nevermind the fact that all those defenses carry with them potential vulnerabilities which could themselves be used in an attack...

that said, it isn't necessarily true that we can't use the asymmetry to our benefit... we can, we just can't do it as a defender... richard bejtlich would i'm sure suggest what he likes to call threat-centric security but which, in the context of this post, i'll call offensive security - that is where we (who have things that need defending) go and 'attack' (as in track down, identify, charge, and imprison) those who would attack us... to quote sandi hardmeier:

Also - I have a special warning for the bad guys - you can hide from some of us, but you can't hide from all of us, and you most certainly cannot hide from your victims.

alas, this too is a kind of defense, and although we can turn the asymmetry around for individual cases, to actually protect our systems this way we'd need to go after all potential attackers (which is an unknowable set of people) whereas the attackers realistically only need to worry about the actual organizations/people they attacked (which is a much smaller and more knowable set of people)... ultimately, reducing the pool of attackers is much the same as reducing the pool of vulnerabilities - for each one you remove there's more where that came from...

so there really doesn't seem to be a good way to turn the asymmetry around and make defending easier than attacking... there are things that can improve the situation to some extent but it can be a real balancing act sometimes...

i know there's no panacea but i still want one, darnit!

have you read this post by lonervamp about the silver bullet syndrome? forgetting his specific example of jericho forums for the moment, i agree whole-heartedly with his observation that although we all seem to agree that there is no panacea people still seem to talk and act as though they expect their to be one...

need an example besides the jericho one? well anton chuvakin has been kind enough to provide us with one this evening that involves anti-virus... he's abandoned known-malware scanning completely after a friend of his had to rebuild their system despite being 'protected' by a major brand av....

now i'm not going to debate the merits of the decision itself, if he wants to use a whitelist instead of a blacklist, that's his decision and it's certainly a workable one... the problem is the motivation - getting fed up because of an instance of av failing (or even many instances) points to (as mike rothman would put it) mismatched expectations... if you know and agree that there is no panacea then you shouldn't be overly bothered by instances of failure, you should be expecting failure...

so what's going on here? i think that although we more or less all agree that there is no panacea, people don't seem to appreciate what that really means... i suspect that the use of the term panacea itself may be obscuring the real implications so i'm going to put it in simple terms that everyone, expert and novice alike, can understand:

all preventative measures fail

that's right, each and every single last one of them... that is what it means to truly accept that there is no panacea, you have to accept that there will be failures... getting fed up with the failures is an emotional rather than rational reaction, and if you base your decisions on it you are likely to be disappointed in the future when it turns out that the next big thing fails too...

people don't like failure, however, and they certainly don't want to accept it... this is a shame because if you're going to develop a successful security strategy you have to not only accept failure, you have to anticipate it... anticipating failure is really a cornerstone of strategic thinking, without it there would be no impetus to devise contingency plans, and without those a strategy is nothing more than a basic plan and a lot of poorly founded hope... in short you need to learn to succeed by planning for failure rather than running blindly from it...