who knows what the future may bring? well lots of people seem to think they do, and bruce schneier even goes so far as to predict what security will look like 10 years from now. much like long term weather forecasts, he is almost certainly wrong - at least i hope he is, because the picture he paints is distinctly dystopian.
no, that's not just an interpretation - a future where we the users are viewed as parasites living off the life-blood of corporations is not a happy shiny place to live. i can certainly see where he's coming from, though, as the beginnings of that are already visible with such schools of thought as the one that refers to users as product (i.e. we aren't facebook's customers, we're they're product). we are being increasingly objectified and devalued by corporate interests. the entertainment industry (and let's not forget their associated lobby, as the group is now as much a political force as they are a corporate one) is certainly leading the anti-consumer charge in the quest to justify their sense of corporate entitlement - but unlike bruce (who is himself part of the corporate machine) i have faith that society will eventually tip the scales back towards our favour.
we've already seen a time when businesses had all the power and the little guy was at their mercy. it happened during the industrial revolution. we fought back. we won. we outnumber them and they can't exist without us (while human history proves we can exist without them). to call us, rather than blood-sucking corporations, the parasites is to ignore nature in favour of business. that kind of backwards world view was not then and is not now a natural one and nature is something you cannot beat.
but beyond my faith in humanity, i also think schneier is wrong because he's misunderstanding the signs he's reading. for example, referring to iphones as special purpose computers instead of general purpose ones and citing them as evidence of the demise of the general purpose computer demonstrates that bruce hasn't the foggiest notion of what the distinction between a special purpose and general purpose computer really is. what we may well be witnessing is the end of the personal computer in favour of the mobile computing device, but that is an entirely different matter with entirely different repercussions. for one thing, a world without general purpose computers is a world without the world wide web. it is a world without iphone apps, a world without game consoles, a world without software. the iphone may exist in apple's walled garden, but i can (and do) get the same limitations on my PC using application whitelisting. that doesn't turn my PC into a special purpose computer any more than it does the iphone - it just makes it locked down.
so long as the computer is technically capable of running arbitrary code (which is exactly what happens when you install an iphone app or visit a website that has javascript or flash or any of the other wonderful interactive technologies out there) it is a general purpose computer (it satisfies what fred cohen referred to as the generality of interpretation). a world without general purpose computers is very, very hard to imagine. bruce, thinking the difference between special and general purpose computing can be illustrated as the difference between an iphone and a PC, sees a world that technically isn't much different from our own. but the difference between special and general purpose computers is more accurately illustrated as the difference between a cheap simple hand-held calculator and the fancier more expensive programmable variety. a world where computing devices are as inflexible as cheap hand-held calculators is a strange world indeed. you might think that there must be some sort of middle ground between the two that would allow for something more (and then surely the iphone inhabits that middle ground) but ed felton covered the fallacy of the almost general purpose computer a long time ago.
without the elimination of general purpose computing you cannot eliminate user choice. you cannot eliminate the emergence of technologies that empower us to throw off the yolk of corporate interests. the linuxes and firefoxes of the world will continue into the future, and the more anti-consumer that corporations become, the more consumers will choose those alternatives. we are not and never will be the parasites in the relationship with business. we are not facebook's product, we are their patrons. the advertisers are not their customers, they're more like the hotdog vendors at a stadium; they only make money so long as we show up and buy something and eventually we will stop showing up at the facebook stadium (just as we stopped showing up to friendster and myspace) and they'll have to chase us to our new favourite spot like the parasites they are.
Showing posts with label fred cohen. Show all posts
Showing posts with label fred cohen. Show all posts
Tuesday, December 21, 2010
Friday, July 02, 2010
to create malware or not to create malware
so ed moyle over at security curve has responded to some points i made in a previous post about the anti-malware community's ethical stance on malware creation.
ed's response is twofold. first he countered my assertion about what would happen if the CDC went around creating new diseases with a practical example by pointing out that some biologists actually do create new viruses. a little further on he makes mention of the concept of ethical relativity and this is important, because ethics are relative in a number of different ways. not only can ethics be relative in terms of degree (A is ethically worse than B) but also in terms of the frame of reference (the ethical rules for one group don't necessarily apply to a different group - for example there are things that would be unethical for a doctor to do but might be fine for you or i). i chose CDC specifically because, with their focus being on the control/prevention of disease, they are more analogous to the anti-malware community than biologists in general would be. if there were such a thing as computer virologists (or more specifically if there were ones who hadn't already chosen a side in the pro/anti-malware battle) they might be more in line with biologists ethically. from my perspective, though, i have to wonder if that makes them amoral with respect to malware.
philosophically (where ed's mention of ethical relativity actually came from) ed made the argument that something that is normally considered unethical might be considered alright if there was a bigger ethical 'win' as a result. what he's actually getting at is something that might be more readily recognized as the concept of the lesser of two evils. he contends that there might be scenarios in the realm of research where the good done as a result of creating malware outweighs the bad. i'm going to do something totally unexpected and agree with him, but with a caveat that you'll see in a minute.
from early on, fred cohen held out the possibility of beneficial viruses (no doubt there are even earlier citations possible but this will do), and in the beginning i thought they were possible too until i read vesselin bonchev's paper Are "Good" Viruses Still a Bad Idea? vesselin made perhaps the most salient of all points about the criteria by which a supposed good virus can be determined to be actually good. the "good" end result has to be something that can't be achieved any other way.
now vesselin had it slightly easier here because he was looking specifically at viruses, at self-replicating malware, which is a more narrowly defined problem than 'good malware' or 'good reasons to create malware in the lab'. vesselin's argument didn't leave a lot of room for good viruses - virtually everything you can think of doing with a self-replicator can also be done with non-replicative code and thus without the risks inherent in self-replication.
i mention vesselin's paper because that salient point he made extends to this case as well. unspoken in ed moyle's bank robbery example is that there is only 1 way to keep the hidden girl alive - by lying. if there were another way, would lying to save the little girl's life still be ok? if you choose the lesser of 2 evils, when a 3rd option with no evil whatsoever were available, then doesn't choosing the lesser evil mean that you're still doing evil unnecessarily?
that's where things stand in the anti-malware community. although it may be hypothetically possible to construct a scenario where malware creation is the least evil option, to my knowledge no one has managed to present such a scenario (with the exception of exploit code* for demonstrating the presence and importance of vulnerabilities), and so the no-malware-creation rule has no good exceptions yet. the need for new malware in testing (the root of the current discussion of malware creation ethics) can already be met in 2 different ways (retrospective testing or real-time/real-life testing that tests against suspect samples as they're discovered) that don't involve malware creation at all.
(* 2010/07/19: edited to add the exception case for exploit code, as pointed out by vesselin bontchev)
ed's response is twofold. first he countered my assertion about what would happen if the CDC went around creating new diseases with a practical example by pointing out that some biologists actually do create new viruses. a little further on he makes mention of the concept of ethical relativity and this is important, because ethics are relative in a number of different ways. not only can ethics be relative in terms of degree (A is ethically worse than B) but also in terms of the frame of reference (the ethical rules for one group don't necessarily apply to a different group - for example there are things that would be unethical for a doctor to do but might be fine for you or i). i chose CDC specifically because, with their focus being on the control/prevention of disease, they are more analogous to the anti-malware community than biologists in general would be. if there were such a thing as computer virologists (or more specifically if there were ones who hadn't already chosen a side in the pro/anti-malware battle) they might be more in line with biologists ethically. from my perspective, though, i have to wonder if that makes them amoral with respect to malware.
philosophically (where ed's mention of ethical relativity actually came from) ed made the argument that something that is normally considered unethical might be considered alright if there was a bigger ethical 'win' as a result. what he's actually getting at is something that might be more readily recognized as the concept of the lesser of two evils. he contends that there might be scenarios in the realm of research where the good done as a result of creating malware outweighs the bad. i'm going to do something totally unexpected and agree with him, but with a caveat that you'll see in a minute.
from early on, fred cohen held out the possibility of beneficial viruses (no doubt there are even earlier citations possible but this will do), and in the beginning i thought they were possible too until i read vesselin bonchev's paper Are "Good" Viruses Still a Bad Idea? vesselin made perhaps the most salient of all points about the criteria by which a supposed good virus can be determined to be actually good. the "good" end result has to be something that can't be achieved any other way.
now vesselin had it slightly easier here because he was looking specifically at viruses, at self-replicating malware, which is a more narrowly defined problem than 'good malware' or 'good reasons to create malware in the lab'. vesselin's argument didn't leave a lot of room for good viruses - virtually everything you can think of doing with a self-replicator can also be done with non-replicative code and thus without the risks inherent in self-replication.
i mention vesselin's paper because that salient point he made extends to this case as well. unspoken in ed moyle's bank robbery example is that there is only 1 way to keep the hidden girl alive - by lying. if there were another way, would lying to save the little girl's life still be ok? if you choose the lesser of 2 evils, when a 3rd option with no evil whatsoever were available, then doesn't choosing the lesser evil mean that you're still doing evil unnecessarily?
that's where things stand in the anti-malware community. although it may be hypothetically possible to construct a scenario where malware creation is the least evil option, to my knowledge no one has managed to present such a scenario (with the exception of exploit code* for demonstrating the presence and importance of vulnerabilities), and so the no-malware-creation rule has no good exceptions yet. the need for new malware in testing (the root of the current discussion of malware creation ethics) can already be met in 2 different ways (retrospective testing or real-time/real-life testing that tests against suspect samples as they're discovered) that don't involve malware creation at all.
(* 2010/07/19: edited to add the exception case for exploit code, as pointed out by vesselin bontchev)
Saturday, May 16, 2009
fred cohen says anti-virus doesn't work
the EICAR (european institute for computer antivirus research) conference was held earlier this week and something which may at first blush seem quite curious happened... fred cohen (a keynote speaker, the father of computer viruses, and the man behind the seminal academic treatment of the subject) said that anti-virus doesn't work...
i wish i'd been there to see that (actually no i don't, i almost certainly would have rolled my eyes, crossed my arms and gone to sleep), but since i'm not part of the industry and flying over to berlin on my own dime is kinda out of the question i had to miss out... it seems i wouldn't have even heard about it if not for randy abrams posting about it here... i've waited patiently for a couple of days now for anyone else to write something about it so i could get more details of what was actually said, but that doesn't seem to be forthcoming... even eicar's site only tells me that the title of his talk was supposed to be "Computer Virology: 25 Years From Now"...
so, since i don't have first hand experience of the conference to give me a clue as to what on earth he was thinking, i went and did some research to see if anything he's said or written in the past might give me a clue and i believe i've found what i was looking for...
in an article on his site titled "Unintended Consequences" it starts to become clear that he feels the computer security industry is in the practice of detecting and reacting to bad things instead of preventing and deterring them, and he paints that in a rather negative light... when i read this i was struck - if he thinks anti-virus (probably one of the most mainstream parts of the computer security industry) is about detection and not prevention then he's doing it wrong!... in my earlier post on defensive lines in anti-malware i illustrate pretty clearly how anti-virus technologies (both the ones that security numpties consider av and the ones they don't) are employed as preventative measures, preventing such things as access to threats, execution of threats, and behaviour of threats (among other things)...
the thing is, fred cohen is really not the sort of person you'd expect to be using av wrong... thankfully i found a pair of interviews with him - one called "Three Minutes With Fred Cohen, Virus Trends Tracker", and the other "Fred Cohen - Not all virus writing is a crime"... although anti-virus is certainly used for prevention, it's underlying mechanisms are largely detection-based - however when cohen talks of prevention he's referring to the type where the underlying mechanism is sort of like an immunity... it all became clear to me when he said we should be using systems that are less susceptible to viruses in the first place - systems that have more limited functionality... this relates back to his 1984 paper Computer Viruses - Theory and Experiments where, in the section on prevention (i really should have looked there earlier) he discusses the 3 key properties of a system that allow viruses to spread - sharing, transitivity of information flow, and the generality of interpretation...
systems with limited functionality refers specifically to the third of these properties - the generality of interpretation - by limiting the functions that a system can perform you limit what can be done as a result of interpreting data as code... cohen poses the examples of turning off macros in ms word, or turning off javascript in the browser - i would follow those up with more contemporary examples such as microsoft recently announcing the disabling of autorun for flash media, or the increasing trend (at least among security conscious users) to use alternate PDF viewers as opposed to Adobe's own Acrobat Reader which has been bloated with unnecessary (and frankly unsafe) functionality for a long time...
i'm not going to try and detract from his arguement by saying the idea doesn't have merit - it does... i even considered whether my defensive lines post needed another line regarding system immunity, though i later realized that limited functionality is already covered by existing lines (as it's just another method of preventing exection and/or particular behaviours)... the problem isn't that his argument in favour of using this technique has merit, the problem is figuring out how he could think anti-virus is broken and this technique isn't - or what he thinks the security industry can do about limiting functionality...
the very existence of the security industry underscores the fact that there has historically been no (and largely still is no) place for security in the rest of the computer industry... limiting functionality is the domain of the original product developers, not 3rd party security companies - the norton's and mcafee's of the world don't have the freedom to cripple Acrobat Reader for example (at least not without getting sued)... and the original product developers by and large aren't limiting functionality because that goes against consumer expectations for technology... technology is supposed to empower us to do more, to do things better/faster, etc - so it's a given that when we choose something we expect to empower us, we aren't going to go with the less powerful option... this is born out by history as well because there have always been less functional/powerful options available and the market has consistently selected against them in favour of the bloated product suites and application platforms...
furthermore, limiting applications is all well and good but there's plenty of malware out there that exists as native binary executables, and limiting the operating system's functionality (or worse, that of the hardware itself) to prevent things like self-replication or botnet command and control communication is a far trickier proposition...
so given the difficulty in getting more adoption of limited systems and given the fact that even cohen isn't suggesting limiting things to the point of systems with fixed first order functionality, i can't help but wonder how he could consider this any less flawed an approach in practice than anti-virus... it is clear to me that it will be just as possible to work around the limitations he's proposing as it is to work around anti-virus technologies, and limited functionality defenses are a lot less agile than things like known-malware scanning so when those special cases come along it will cost a great deal more to redesign a system to further limit functionality so as to deal with such special cases...
that should give you a clue as to my opinion of limited functionality-based defenses - they have promise as a complement to anti-virus techniques... anti-virus may not work in the sense that it's not completely effect at preventing malware infestation, but limited functionality systems aren't either... anti-virus may not work in the sense that it's a computationally expensive approach to prevention, but limited functionality has logistical costs for development, marketing, and maintenance that we may never completely overcome... i fully endorse the idea of selecting software that only has as much power and functionality as you need and no more, but i still think you should use anti-virus right along side that...
frankly, at the end of the day, the main difference between systems that are designed to have more limited functionality and ones where anti-virus is deployed is that the former's limitations are baked in while the latter's limitations are bolted on (because like it or not when an anti-virus stops a piece of malware from executing on your system it is effectively limiting your system's ability to perform the function that malware represents)... that appears to be what cohen's real contention is about - that baked in is better than bolted on... in some ways that may be true, but in others (like the matter of agility) it's definitely not (because it's easier to change the bolt than it is to change the whole system)...
i wish i'd been there to see that (actually no i don't, i almost certainly would have rolled my eyes, crossed my arms and gone to sleep), but since i'm not part of the industry and flying over to berlin on my own dime is kinda out of the question i had to miss out... it seems i wouldn't have even heard about it if not for randy abrams posting about it here... i've waited patiently for a couple of days now for anyone else to write something about it so i could get more details of what was actually said, but that doesn't seem to be forthcoming... even eicar's site only tells me that the title of his talk was supposed to be "Computer Virology: 25 Years From Now"...
so, since i don't have first hand experience of the conference to give me a clue as to what on earth he was thinking, i went and did some research to see if anything he's said or written in the past might give me a clue and i believe i've found what i was looking for...
in an article on his site titled "Unintended Consequences" it starts to become clear that he feels the computer security industry is in the practice of detecting and reacting to bad things instead of preventing and deterring them, and he paints that in a rather negative light... when i read this i was struck - if he thinks anti-virus (probably one of the most mainstream parts of the computer security industry) is about detection and not prevention then he's doing it wrong!... in my earlier post on defensive lines in anti-malware i illustrate pretty clearly how anti-virus technologies (both the ones that security numpties consider av and the ones they don't) are employed as preventative measures, preventing such things as access to threats, execution of threats, and behaviour of threats (among other things)...
the thing is, fred cohen is really not the sort of person you'd expect to be using av wrong... thankfully i found a pair of interviews with him - one called "Three Minutes With Fred Cohen, Virus Trends Tracker", and the other "Fred Cohen - Not all virus writing is a crime"... although anti-virus is certainly used for prevention, it's underlying mechanisms are largely detection-based - however when cohen talks of prevention he's referring to the type where the underlying mechanism is sort of like an immunity... it all became clear to me when he said we should be using systems that are less susceptible to viruses in the first place - systems that have more limited functionality... this relates back to his 1984 paper Computer Viruses - Theory and Experiments where, in the section on prevention (i really should have looked there earlier) he discusses the 3 key properties of a system that allow viruses to spread - sharing, transitivity of information flow, and the generality of interpretation...
systems with limited functionality refers specifically to the third of these properties - the generality of interpretation - by limiting the functions that a system can perform you limit what can be done as a result of interpreting data as code... cohen poses the examples of turning off macros in ms word, or turning off javascript in the browser - i would follow those up with more contemporary examples such as microsoft recently announcing the disabling of autorun for flash media, or the increasing trend (at least among security conscious users) to use alternate PDF viewers as opposed to Adobe's own Acrobat Reader which has been bloated with unnecessary (and frankly unsafe) functionality for a long time...
i'm not going to try and detract from his arguement by saying the idea doesn't have merit - it does... i even considered whether my defensive lines post needed another line regarding system immunity, though i later realized that limited functionality is already covered by existing lines (as it's just another method of preventing exection and/or particular behaviours)... the problem isn't that his argument in favour of using this technique has merit, the problem is figuring out how he could think anti-virus is broken and this technique isn't - or what he thinks the security industry can do about limiting functionality...
the very existence of the security industry underscores the fact that there has historically been no (and largely still is no) place for security in the rest of the computer industry... limiting functionality is the domain of the original product developers, not 3rd party security companies - the norton's and mcafee's of the world don't have the freedom to cripple Acrobat Reader for example (at least not without getting sued)... and the original product developers by and large aren't limiting functionality because that goes against consumer expectations for technology... technology is supposed to empower us to do more, to do things better/faster, etc - so it's a given that when we choose something we expect to empower us, we aren't going to go with the less powerful option... this is born out by history as well because there have always been less functional/powerful options available and the market has consistently selected against them in favour of the bloated product suites and application platforms...
furthermore, limiting applications is all well and good but there's plenty of malware out there that exists as native binary executables, and limiting the operating system's functionality (or worse, that of the hardware itself) to prevent things like self-replication or botnet command and control communication is a far trickier proposition...
so given the difficulty in getting more adoption of limited systems and given the fact that even cohen isn't suggesting limiting things to the point of systems with fixed first order functionality, i can't help but wonder how he could consider this any less flawed an approach in practice than anti-virus... it is clear to me that it will be just as possible to work around the limitations he's proposing as it is to work around anti-virus technologies, and limited functionality defenses are a lot less agile than things like known-malware scanning so when those special cases come along it will cost a great deal more to redesign a system to further limit functionality so as to deal with such special cases...
that should give you a clue as to my opinion of limited functionality-based defenses - they have promise as a complement to anti-virus techniques... anti-virus may not work in the sense that it's not completely effect at preventing malware infestation, but limited functionality systems aren't either... anti-virus may not work in the sense that it's a computationally expensive approach to prevention, but limited functionality has logistical costs for development, marketing, and maintenance that we may never completely overcome... i fully endorse the idea of selecting software that only has as much power and functionality as you need and no more, but i still think you should use anti-virus right along side that...
frankly, at the end of the day, the main difference between systems that are designed to have more limited functionality and ones where anti-virus is deployed is that the former's limitations are baked in while the latter's limitations are bolted on (because like it or not when an anti-virus stops a piece of malware from executing on your system it is effectively limiting your system's ability to perform the function that malware represents)... that appears to be what cohen's real contention is about - that baked in is better than bolted on... in some ways that may be true, but in others (like the matter of agility) it's definitely not (because it's easier to change the bolt than it is to change the whole system)...
Tuesday, April 08, 2008
no such thing as non-executable files
i happened to notice a post by benny ketelslegers presenting a digested view of a symantec post by andrea lelli on file format vulnerabilities... i didn't give the symantec post much thought when i first encountered it, but when i read benny's post i realized that i (and perhaps many others) have been taking the issue of executable files for granted and that the word choices being made could lead to an altogether wrong concept of what a program is and by extension what sorts of things can effectively be malicious agents on a computer...
perhaps my first exposure to the idea that there are no non-executable files came when i was still a teenager learning that for every sequence of bytes there exists a turing machine for which that sequence of bytes is a virus... i didn't even really know that much about turing machines at the time (other than they were a way to model computers) but i understood what it meant - for every sequence of bytes there exists a possible computing environment where those bytes are interpretable as a self-replicating program...
it's an interesting statement, but it's awfully narrowly focused on viruses... it turns out that the focus on viruses was just because of the context... in reality, for every sequence of bytes there exists a possible computing environment where those bytes are interpretable as a program...
that probably still sounds pretty formal to the average person, but not as formal as fred cohen's reference to the generality of interpretation... the simplest way i can express this is that there is no fundamental difference between data and code, that program code basically is data but that it's data for which there happens to be some part of the computer (some other program or subsystem) that will treat it as a collection of one or more instructions... any piece of data you can imagine can potentially be interpreted (or even misinterpreted) as program code, although it may not have much meaning or do anything useful as a program...
this ability to treat arbitrary data as code is what allows us to add new, previously unimagined capabilities to our computers in the form of new software... it's what makes our general purpose computers 'general purpose', but there's still more to the story... the ability to treat a particular chunk of data as code in practice may not even be intentional, it can be an emergent property resulting from excessive complexity and/or poor implementation... this leads to what i often refer to as exotic execution and data that makes use of such a property is generally referred to as an exploit...
all this is to say that all data may also be considered by the computer to be program code under the right conditions, and determining if those conditions have or have not been met can be very hard... as such, to say something is not program code, to say that it is non-executable is an oversimplification that can (especially when uttered by authoritative sourced like symantec) promulgate an idea that there are safe, non-executable file types which in turn gives people a false sense of security when handling those types of files...
indeed, the majority of the file types referenced by the symantec post explicitly support the ability to contain code that their respective reader applications are intended to execute (whether that be javascript in pdf documents or visual basic in microsoft office documents)... the fact that those file types can also carry known exploits should have little bearing and the very fact that people need to be corrected about the safety of such files points to a more endemic false sense of security about data in general... there are in fact no safe file types and no such thing as non-executable files...
perhaps my first exposure to the idea that there are no non-executable files came when i was still a teenager learning that for every sequence of bytes there exists a turing machine for which that sequence of bytes is a virus... i didn't even really know that much about turing machines at the time (other than they were a way to model computers) but i understood what it meant - for every sequence of bytes there exists a possible computing environment where those bytes are interpretable as a self-replicating program...
it's an interesting statement, but it's awfully narrowly focused on viruses... it turns out that the focus on viruses was just because of the context... in reality, for every sequence of bytes there exists a possible computing environment where those bytes are interpretable as a program...
that probably still sounds pretty formal to the average person, but not as formal as fred cohen's reference to the generality of interpretation... the simplest way i can express this is that there is no fundamental difference between data and code, that program code basically is data but that it's data for which there happens to be some part of the computer (some other program or subsystem) that will treat it as a collection of one or more instructions... any piece of data you can imagine can potentially be interpreted (or even misinterpreted) as program code, although it may not have much meaning or do anything useful as a program...
this ability to treat arbitrary data as code is what allows us to add new, previously unimagined capabilities to our computers in the form of new software... it's what makes our general purpose computers 'general purpose', but there's still more to the story... the ability to treat a particular chunk of data as code in practice may not even be intentional, it can be an emergent property resulting from excessive complexity and/or poor implementation... this leads to what i often refer to as exotic execution and data that makes use of such a property is generally referred to as an exploit...
all this is to say that all data may also be considered by the computer to be program code under the right conditions, and determining if those conditions have or have not been met can be very hard... as such, to say something is not program code, to say that it is non-executable is an oversimplification that can (especially when uttered by authoritative sourced like symantec) promulgate an idea that there are safe, non-executable file types which in turn gives people a false sense of security when handling those types of files...
indeed, the majority of the file types referenced by the symantec post explicitly support the ability to contain code that their respective reader applications are intended to execute (whether that be javascript in pdf documents or visual basic in microsoft office documents)... the fact that those file types can also carry known exploits should have little bearing and the very fact that people need to be corrected about the safety of such files points to a more endemic false sense of security about data in general... there are in fact no safe file types and no such thing as non-executable files...
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