Antivirus Software is a Hack

- -

- I read a really terrific article today about computer security and - really dumb ideas or trends that have developed in this field. It's - M. Ranum's The Six Dumbest Ideas in Computer Security, and I highly recommend reading through the whole thing. It's got - great anecdotes and really simple language for what I consider to be - some of the obvious issues with the way programmers and sysadmins think - about security (myself included). One portion of it (idea #2), however, - finally put something into words that I've felt for a really long time. - It enables me to explain why I think all antivirus software is a total - hack and is virtually useless. -

- -

- hack
- 1. n. Originally, a quick job that produces what is needed, but not - well. -

- -

- This is the Jargon File's definition of a hack. And to me, this is what - antivirus software is. Antivirus software, as I understand it, emerged - in the mid to late 1980s and became prolific in the 1990s. In the 2000s - it was considered an essential piece of software and people were paying - for yearly subscriptions for antivirus suites from Norton, Avast, and - McAfee. -

- -

- The most basic functionality of an antivirus program is to determine - whether malware exists on a host operating system. The typical method of - doing this is to use a collection of virus definitions and compare each - and every potentially-infected file with each and every definition to - determine whether the file is malware or has been infected by some. An - over-simplified way of implementing this is to store a collection of - hashes, each taken from a known potentially unwanted program or - infectious executable. You can then hash entire files or portions of - files and compare the checksums to see whether a file contains or is - equivalent to the definition, and is therefore infected and shouldn't be - executed. Some security suites go beyond this with heuristic matching, - but if you run an antivirus that has to "update definitions" on a - routine basis, it probably works something like this*. With any luck, it - does it without being a total detriment to system performance. Ideally - it also doesn't act like a piece of malware itself by making itself near - impossible to remove (looking at you, McAfee). -

- -

- To me, a virus definition database is "enumerating badness" (Ranum's - Dumb Idea #2). The premise is that it is not only logical but even - possible to compile a list of all potentially unwanted - programs, viruses, ransomware, and worms. An environment of trust should - be built around the programs that you want to run (read: - allow to run), not the other way around. Picture an operating - system where no binary file can be executed unless it is specifically - flagged as being allowed to. Oh and picture also being able to restrict - this execution to just the file's owner, or other groups of users. - Wouldn't it be easier to store the list of 30 odd programs that you and - other system users trust to be run than the thousands (millions?) of - programs that are infectious, forbidden, or unwanted? What about when - those trusted applications become compromised? Would it not also be - easier to maintain a list of checksums for those binaries and compare - those checksums before they're executed to make sure they haven't been - infected or replaced? -

- -

- The answer is yes, it would be easier. And yes, it is easier. Of course, - your system has to work that way. Antivirus software is a hack because - it's a hack-y solution to a problem that has a better, simpler solution. - It also has the potential for making a ton of money but I won't go into - that. It's easier to enumerate goodness, to specifically open up to a - select few trustworthy applications. Good lists are usually shorter than - bad lists. This builds on top of Ranum's Dumb Idea #1: Default Permit. - You wouldn't configure a firewall to just block some known bad ports and - traffic. You configure it to block all of it, and then whitelist the - ones you know you can trust. You wouldn't configure a browser ad-blocker - to permit all ads, and select the ones you don't want to see. You block - all of them! Then, if there are sites or ads you're okay with seeing, - you whitelist them. You shouldn't default permit all programs to be - given control over your computer, and then meticulously list the ones - that don't have that permission. -

- -

- Oh and of course, as always, there's free software that lets you do - this. You don't have to pay for an antivirus suite, or even use an - unpaid one that slows down your computer or barrages you with ads. On - the BSDs and virtually all Linux distributions, there are built-in tools - to control access and execution of binaries. There are additional tools - that you can install that check whether binaries (in locations like - /bin or /usr/local/bin have been modified - since you last used them. On Windows, the story is a little different. - Most home Windows 10 users are automatically allowed to install and run - any software they want to by default. Windows Server does have Software - Restriction Policies that allow you to create a "default deny" policy - and whitelist only the software that's allowed to run. If you're using a - home edition you probably have to look for software that lets you do - this. I haven't tried any of them so I'm not going to endorse or even - name them here. -

- -

- Preventing malware from running on your system is a problem. Solving - this problem is the right thing to do. But please, try to solve it the - right way. I stopped using an antivirus after I moved out and got to - control my own computer. I don't think it ever did me any good besides - flag false positives (a lot of the time with programs or applications - that I wrote, which weren't malicious in any way!) and grind my spinning - disk to a halt. Evaluate what software you use. Is most of it online? - Are there one or two applications that you know you need to use? How - often do you install and use unknown or untrusted software? Odds are you - can come up with a list of very few programs that you want or need to - use. If it's less than 100,000, you're probably better off with a - default deny policy than an antivirus suite. -

- -

- * What I didn't mention here is that as soon as a new piece of malware - is constructed, if it's different enough from its predecessors, it's - impervious to all antivirus suites on the planet that don't have it in - their definitions. So until that malware is used, detected, and added to - the list, it has free reign. -