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New Virus Attacks Via RAR Files

sscottsci writes "A new article at eWeek indicates that Virus writers are using .RAR files to bypass Filters and Anti-Virus systems to infect computers. Most anti-virus software cannot scan a .RAR file, and most firewalls do not block the extension yet."

42 of 585 comments (clear)

  1. Is this really a big deal? by FyRE666 · · Score: 4, Interesting

    ...most firewalls do not block the extension yet.

    Well, I know of a few that do now... Seriously, is this that much of a threat? Winzip (AFAIK) doesn't handle Rar archives, and most users wouldn't know how to open one if they did find one in their inbox...

    1. Re:Is this really a big deal? by LoRdTAW · · Score: 5, Informative

      Well it could definatly cause a problem with warez. Most warez is usually packed using RAR.

    2. Re:Is this really a big deal? by zbeeble · · Score: 4, Insightful

      I suppose it depends what you download. But quite a lot of games and movies are compressed with rar. Also I know a few people who send rar files through their work address's because zip is blocked.

    3. Re:Is this really a big deal? by Jhon · · Score: 4, Interesting

      I doubt eweek's demographic is strong in the 'warez' crowd. And if your in charge of a corporate firewall and your users are downloading 'warez', you've got serious problems. .rar have been blocked at our proxy (both extension and mimetype) and email scanner for years. Along with rtf, password protected zip files, exe files, cpl files, etc. It's a long list.

      I'm waiting for the email attachments without extension that include 'instructions' on how to 'save as' to add the extenion, then execute the code. The password protected zip file worms were close...

    4. Re:Is this really a big deal? by hab136 · · Score: 4, Insightful
      I've always wondered why a virus writter couldn't just wrap a virus in a self-extracting encryption algorithm? [...] How could scanning for a virus figure that as a virus (unless you block all executables)?

      You've answered your own question - most corporations and free email providers block executables.

    5. Re:Is this really a big deal? by Rei · · Score: 4, Funny

      ... because you can detect the part that does the self-extracting, of course. :)

      A more clever approach is to have another program do the extracting for you - for example, to distribute it as a password-protected zip file and make the password known to the user. That way, you don't need the identifiable extractor.

      --
      "Lock and load, Brides of Christ!"
    6. Re:Is this really a big deal? by stupidfoo · · Score: 5, Informative

      Unfortunately, a malicious person can still e-mail a macro virus by merely changing a .DOC file's extension to .RTF. (Microsoft should prevent Word from running macros in files with .RTF extensions, but it doesn't.)

      http://www.infoworld.com/articles/op/xml/00/10/30/ 001030oplivingston.html

    7. Re:Is this really a big deal? by ThosLives · · Score: 5, Interesting
      Actually, this points at a more fundamental issue. What happens if you simply take the extension off the file and set the MIME type to something like "binary stream" and just send it "raw"? I often have to rename files to get them through company (*ahem* outlook) filters that block files.

      Associating the name of a file with its content type is quite ludicrous; Apple used to do a better job of this with the file resources (the average user couldn't change file type - the name wasn't the type!) but with the transition to OS X (Unix) the metadata with files can be lost and is associated via file extension again.

      This boils down to the fact that digital data is inherently untyped; there is no way to tell if something is *really* a word document, bitmap, executable, or a random collection of bits (you can use signatures in the data to help with this, but that's about it).

      However, more on topic: I didn't know RAR files had "executable" content. If a file in a .RAR archive has a virus, that's no different than any other "hidden" trojan: shouldn't the virus scanner realise there is a problem as soon as the user tries to do something with the uncompressed/unencrypted file?

      --
      "There are a dozen opinions on a matter until you know the truth. Then there is only one." - CS Lewis (paraprhase)
    8. Re:Is this really a big deal? by Trejkaz · · Score: 4, Insightful

      If zip (or any) files are blocked, I like sending files encrypted, or merely scrambled.

      You would be surprised how few email filters detect an attachment which is simply sent as Base64 or UUEncoded text, in the body. As it's not an attachment, it frequently gets ignored.

      --
      Karma: It's all a bunch of tree-huggin' hippy crap!
    9. Re:Is this really a big deal? by Lord+Kano · · Score: 4, Insightful

      doubt eweek's demographic is strong in the 'warez' crowd. And if your in charge of a corporate firewall and your users are downloading 'warez', you've got serious problems.

      Contrary to popular opinion, Corporate admins aren't the only people who worry about security.

      LK

      --
      "Hi. This is my friend, Jack Shit, and you don't know him." - Lord Kano
    10. Re:Is this really a big deal? by HD+Webdev · · Score: 5, Informative

      Well, I know of a few that do now... Seriously, is this that much of a threat? Winzip (AFAIK) doesn't handle Rar archives, and most users wouldn't know how to open one if they did find one in their inbox...

      .rar archives being infected is very old news as well as every other archive format.

      .rar files have been infected since they have existed and posted to USENET. Rar files are much better than zip files in that people can download (let's say) a .rar that's been split into 15 parts. By using smartpar, even if a part of that .rar is corrupted, Smartpar does parity and other checks to reconstruct the missing part(s)

      As you note, most people don't know about rar files. And even if they do, the anti-virus program will block the virus as soon as the rar set is put back together.

      This is a complete non-issue. Not to mention, Winrar, which creates and reassembles .rar files prompts users to scan files for infections before extracting them.

      --
      This is not a dream, not a dream...we are transmitting from the year 1-9-9-9.
    11. Re:Is this really a big deal? by Jhon · · Score: 5, Insightful
      I'd bet dollars to donuts you are a user, not an admin.

      Attack against users? What user needs to receive .SCR files via email? Seriously. How about .CPL files? How about .exe files? or .com files? Or .bat? or .vbs?

      All the typical vectors of viruses/worms. Who in billing, or sales/marketing, or whatever NEEDS those files?

      When you weigh the cost between the constant drain on IT resources broken OSs (from viruses, unapproved 3rd party apps, etc) would cost, you can't SERIOUSLY hold your position as someone in charge of security.

      Our email server blocks up to 2000 (sometimes more) of the above extentions. Most are IDd viruses (netsky, bagle, etc). The RARE occation it blocks something not IDd is due to a NEW virus that hasn't made it to the virus-def file on the scanners.
      I'm constantly amazed by the number of people..
      And I'm constantly amazed by the number of ACs who pretend to know things and act indignant.
    12. Re:Is this really a big deal? by Anonymous Coward · · Score: 5, Insightful

      You lost your dollars. I'm an MCSE and a CCNA with several years experience as a network admin. Notice I was talking about blocking long lists of extensions. I block executables on my network, both exe and scripts. .EXE, .WSH, .CPL, .BAT, etc. Probably less than 20 extensions, total. I don't block things like .RTF or .XLS or .DOC or .MDB . Yes, it is possible to get various types of malware that way. But there's always a trade off between usability and security. If you want a really secure network, unplug the cable and shut everything down. No viruses or worms, guaranteed. Being able to pass around documents and useful files is part of the reason to have a network. When it gets to the point where your users are sending emails that say "Here's the new database I created. Save it to your desktop and rename it from database.bdm to database.mdb before you open it" then you're part of the problem, not the solution.

      IT people all too often lose perspective. They see the network as an end to itself. The users are just pains in the neck who screw up my beautiful setup and can't be trusted to use my equipment properly. The whole point of having a network is to enable people to do their jobs more effectively and more efficiently, and part of doing the job includes exchanging various types of files. If you're going to stop the network from being useful, why not shut it down and save all the money you're spending on it?

      Blocking executables and having solid, updated virus protection is part of good network security. So is temporarily blocking certain extensions if there's an alert for a new worm or virus that uses a specific type of file. Once your antivirus is updated to reflect the new beastie and the initial infection crisis is over, unblock the extension. Blanket blocking long lists of extensions is a DoS on yourself.

  2. Oh, the horrid memories by Tablizer · · Score: 5, Funny

    Goatse once came to me in a .REAR file. Close enough to avoid.

    1. Re:Oh, the horrid memories by tehshen · · Score: 5, Funny

      I hope you didn't have any wide open ports for a virus to exploit.

      --
      Guy asked me for a quarter for a cup of coffee. So I bit him.
  3. uh... by koreaman · · Score: 5, Funny

    don't accept rar files from people you don't know. And, if you do, don't run random executables inside them?

  4. For those that don't know by Anonymous Coward · · Score: 5, Funny

    Rar files are most commonly used in the legal archiving of binary files and DVDs.

    1. Re:For those that don't know by greenegg77 · · Score: 5, Funny

      So, thats like 50% legal then?
      Nah, it's 100% legal - you're simply a small part of someone's distributed offsite backup and archive model. :D

      --
      --- This .sig for sale - $500 OBO.
  5. Can't scan rar?? by nuclear305 · · Score: 4, Insightful

    "Most anti-virus software cannot scan a .RAR file"

    What? Is it really a case where the software can't scan the archive or is it just that it's not included in the default types of files to scan?

    Just tested this on AVG and it indeed scans rar archives.

  6. No problem! by ChibiLZ · · Score: 4, Insightful

    I fail to see the problem here. TFA says that the .rar contains a file like foto.jpg.exe. This is nothing new, they're just using a better compression program to spread their malware.

    Carry on with the downloading, there's nothing to see here...

    --
    Don't buy WoW Gold! Make it yourself!
  7. The Bright Side by Dachannien · · Score: 4, Insightful

    Fortunately, your grandmother has no clue what a .rar file is or how to open one, leaving her safe from infection by this new method. In fact, it's fairly safe to say that the only people who will get owned by .rar file viruses are lamer hax0r wannabes desperate for more pr0n.

  8. Slashdot Headline! by im_thatoneguy · · Score: 5, Funny

    "Warez is becoming infected with viruses!"

  9. RAR is very popular by bigtallmofo · · Score: 5, Interesting

    I find that more technically-abled people are familiar with and have installed WinRAR or the unix-variant based RAR on their system.

    Of course, such people are less likely to be taken in by a virus, so I'm forced to believe that this new spin on virus writing isn't going to be very effective.

    Similarly, I suppose virus-writers could rename their .exe file to be .txt and leave instructions within the .txt file to rename the file to .exe and from there ask them to execute it but the people that would understand those instructions would not be likely to follow them.

    --
    I'm a big tall mofo.
  10. How's this new? by Phanatic1a · · Score: 5, Insightful

    It's not that there's a virus piggybacked on the .rar, which you infect yourself with by unraring the .rar, it's that they're sending around .rared viruses, which you infect yourself wih if you unrar and then execute them.

    Not seeing the problem, aside from the same old 'don't go happy-assing around executing any damn old executable that someone emails you.'

  11. Re:Good news! by TheRealMindChild · · Score: 5, Interesting

    Maybe you live in the stone age, but I know we use RAR here almost exclusively.

    The reason Zip became so popular was its speed/efficiency comprimise back in the days where it mattered. Using zip, nowadays, is simply due to habit and culture. There isn't an advantage for MOST like there used to be.

    RAR compression is better and has a very nice archive spanning feature. Believe me... this is ever so handy when backing up 40GB of data to a file system/Software that can't address files larger then 2GB. Couple that with the free Stuffit Expander, and I can't come up with a reason you WOULDN't use RAR.

    --

    "When life gives you lemons, don't make lemonade. Make life take the lemons back!" -- Cave Johnson
  12. eWeek ... by jest3r · · Score: 4, Funny

    ... in related news eWeek is able to sell more impressions and generate more revenue by getting coverage on Slashdot for pointless non-news articles such as new Virus hides in compressed files ...

  13. Re:Good news! by wtrmute · · Score: 5, Informative

    Which is a pity, since .rar files are so much more compressible than .zip files. The difference is roughly the same between .gz and .bz2... What would be really easy is for anti-virus writers to include a RAR decompression library and look inside the damned files, rather than reject useful technology for no good reason

  14. ClamAV wins again... by Vellmont · · Score: 5, Informative

    The OSS program ClamAV supports scanning of RAR files. If most anti-virus programs truly don't support RAR format, this is another big win for ClamAV. (I run it on my own server, and as part of an anti spam/virus email service and it runs flawlessly).

    --
    AccountKiller
    1. Re:ClamAV wins again... by j-turkey · · Score: 5, Interesting
      The OSS program ClamAV supports scanning of RAR files. If most anti-virus programs truly don't support RAR format, this is another big win for ClamAV. (I run it on my own server, and as part of an anti spam/virus email service and it runs flawlessly).

      ClamAV just wins period. Not having to pay per-seat licensing is awesome. Never needing to track or renew a subscription is worth every penny you'll spend on Clam AV (umm...$0.00).

      I can't think of any reason to run anything else for an email server. Am I missing something really big that ClamAV just can't do?

      --

      -Turkey

  15. How about a .virus file type? by jptechnical · · Score: 5, Funny

    It seems to me this would be the simplest. Just require the virus makers to use the .virus extension and that will give the AV makers more time to perfect RAR scanning.

    Is anyone with me?

    --

    Boredom's not a burden anyone should bear.
  16. Re:It can't scan INSIDE the rar by nuclear305 · · Score: 4, Interesting

    Apparently I should have been more clear--when testing with AVG it certainly can scan the contents of the archive; I watched as it scanned several exe files I placed inside the archive.

    I can't say I've ever paid much attention to other products but I would have hoped Norton and the like would also have this capability.

  17. concern for warez ... not really by rkmath · · Score: 5, Insightful

    It is true that most warez files are compressed using RAR. But it is also true that the general warez kiddie is not the type who would click on any executable without some virus checking. (Yes - it seems a shame - but the run of the mill warez kiddie is not the clueless user who clicks on every attachment in their email).

    1. Re:concern for warez ... not really by LoRdTAW · · Score: 4, Insightful

      Warez has changed allot in the past years. Gone are the days where you had to know someone with an ftp site (similar to the old BBS days). Back then you had to know what you were doing and how to talk your way in. Enter edonky/kazaa and bittorrent where any joe can download anything they want. I know my brothers friends download using emule and they certainly dont know any more then your average joe.

  18. Comment removed by account_deleted · · Score: 4, Insightful

    Comment removed based on user account deletion

  19. Re:limited scope at best by Temsi · · Score: 4, Insightful

    Personally I prefer WinRAR to any compression program currently available.
    Unfortunately, WinZip sucks beyond words.
    XP's Native handling of Zip files is annoying at best, and is usually one of the first things I disable whenever I install XP.

    I guess I just don't understand what the "nightmare" part is about WinRAR.

    How easy does it have to be, really? Select files, right click, select "add to archive" or "add to filename.rar" and let it run. You're done.
    Extracting is even easier. Right click, select "Extract files" to get a path choice, "Extract Here" to uhm, extract in the current folder or "Extract to filename" which creates a folder with the same name as the file.

    Not to mention the bonus features you get if you bother to open the program, such as file recovery and repair, authentication checking, and the ability to extract from a partial set and even extract broken files if you really, really need them.

    However, this should not be an issue at all, since most people don't have any support for RAR files and therefore can't open them to run the executable inside it (which is monumentally stupid anyway and whoever does, deserves whatever crap they get installed as a result of that action).

    As for the "yet" part of blocking...
    When are we going to put the responsibility in the hands of the user and stop dumbing down the internet? There are those of us who actually know what we're doing, don't open unknown attachments, never get viruses or trojans and always get pissed off when email servers filter out valid files.
    I can't even send a bloody Word document because of the "risk of macros".

    Gimme a freakin' break already.

    Listen up people, if you're too dumb to use email without infecting your computer with the latest malware, maybe you should reconsider email as your communications method of choice.

    --
    -- This sig for rent.
  20. Re:It can't scan INSIDE the rar by orkysoft · · Score: 5, Interesting

    Are you sure AVG didn't actually use the WinRAR you have installed to extract the files, so it can scan them? I know that Ark (a KDE file archiving utility) uses Rarsoft's unrar to operate on RAR files.

    Of course, I don't know whether you have WinRAR installed. Can AVG scan your RAR files if you don't have WinRAR installed?

    --

    I suffer from attention surplus disorder.
  21. Re:Good news! by fireboy1919 · · Score: 4, Insightful

    You give compeling arguments why both zip and rar are used: they became popular when the speed/efficiency compromise mattered. Using either now is simply due to habit and culture.

    There isn't an advantage for most users.

    bzip2, 7z, and many more compression formats are better, and you can find archive spanning programs for every single compression technique because that's such a trivial algorithm to implement.

    I can't come up with a reason why you'd use rar OR zip.

    --
    Mod me down and I will become more powerful than you can possibly imagine!
  22. *sigh* by Nephroth · · Score: 5, Insightful

    This bothers me, it always bothers me when something that is not a vulnerability gets pegged as one. .RAR is not a vulnerability, and it's not a means for spreading viruses any more than any other format is. The vulnerability lies in short-sighted software development that failed to take into account that perhaps .RAR files might be used in addition to .ZIP. It's similar to the claims that international support in mozilla was a vulnerability. It isn't. the USER is the vulnerabitlity, educate the user and the vast majority of these problems will go away.

    Why didn't we have problems like this in the past? Why did virus writers have to be so much more clever? It was because the only people using computers had at least something of an idea of what they were doing. Viruses are, for the most part, easily avoided. It's only when users are clueless and trusting that they are allowed to flourish.

    --
    Our greatest enemy is neither a single man, nor is it a nation, it is, as it has always been, our own greed.
  23. Not sure how this is a new threat by RaguMS · · Score: 5, Insightful

    Correct me if I'm wrong, but I do not understand how this poses a new threat to any system that is protected by a working antivirus.
    Scenario 1: System cannot unpack .rar files. System is safe from virus.
    Scenario 2: System can unpack .rar files. User manually executes virus contained in .rar file. File is first decompressed to the Temp directory, where antivirus catches it.

    I just tested eTrust Antivirus, and it does catch the EICAR test file if I try to open it from a RAR, so I don't see what the problem is.

  24. When will we see a .TXT virus? by Chief+Typist · · Score: 4, Interesting

    It's only a matter of time before we see a .TXT virus. Sounds implausible, but virus writers are very good at adapting to people's work habits.

    Many companies block .ZIP at the perimeter (at a firewall or mail server.) People still have work to do -- so they workaround this block by renaming .ZIP files as .TXT files. We have several clients who *REQUIRE* us to send them files us like this.

    So, once people get into the .TXT -> .ZIP -> unarchive habit, they'll be happy to do the same with a virus.

    And it's going to be fun seeing the whole IT infrastructure that relies on file extensions fall into a crumbling heap.

    -ch

  25. Slow news day! by francisew · · Score: 4, Insightful

    Why exactly does putting viruses into .rar's count as a new virus attack technique?

    This is the same thing that has been going of for a long time with viruses in compressed files.

    What's next, complaining that there are viruses in tar files? Suggesting that propagation of viruses by usb-flash drives, DVD-RW's, SD camera memory and so on... are new vectors of propagation?

    This seems like a really lousy way of trying to instill virus paranoia in people to sell more A/V software.

    Then again, maybe my tinfoil hat is just a bit tight today. Does anyone think there is merit to this article?

  26. Re:Is this really a big deal? Use WordPad by bob+beta · · Score: 4, Funny

    While that might seem an attractive option to some, helpdesk employees worldwide are screaming at the thought of the association for .doc and .rtf files suddenly switching to Wordpad.

    "Why won't my Office work, and what is this silly 'wordpad' that started up?"