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New DoS Vulnerability In All Versions of BIND 9

Posted by kdawson on from the binding-with-briars-my-joys-and-desires dept.

Icemaann writes "ISC is reporting that a new, remotely exploitable vulnerability has been found in all versions of BIND 9. A specially crafted dynamic update packet will make BIND die with an assertion error. There is an exploit in the wild and there are no access control workarounds. Red Hat claims that the exploit does not affect BIND servers that do not allow dynamic updates, but the ISC post refutes that. This is a high-priority vulnerability and DNS operators will want to upgrade BIND to the latest patch level."

17 of 197 comments (clear)

  1. Use Unbound or NSD by nwmcsween · · Score: 5, Informative

    I don't want to bash BIND but it has had a fair amount of sec issues (well a lot), try unbound or nsd instead http://unbound.nlnetlabs.nl/ http://www.nlnetlabs.nl/projects/nsd/

    1. Re:Use Unbound or NSD by medlefsen · · Score: 5, Informative

      or djbdns. We use it where I work and other than a slight adjustment to djb-land it has been wonderful. I know people appreciate how powerful BIND is and maybe some people need that. I suspect though that most people just need their DNS servers to serve their DNS records or provide a caching DNS server for local lookups and for that BIND seems to be bloated and insecure.

  2. Re:Ain't what it used to be.... by ScytheBlade1 · · Score: 4, Informative

    I'm just hoping that CentOS pushes out the update before 10:00 PM MST today.

    Why?

    So I'll get my daily e-mail status update, telling me to do just that: run yum, and then restart (just bind) -- as opposed to seeing it tomorrow.

    As a footnote, it is generally a good thing to subscribe to whichever vendor's security-announce list that you use. It is really nice getting e-mail notifications of security-related package updates. CentOS has one, right here: http://lists.centos.org/mailman/listinfo/centos-announce

  3. Re:Ain't what it used to be.... by lordkuri · · Score: 4, Insightful

    Why in the holy hell would you reboot a server to put a new install of BIND into service?

  4. Only effective against MASTERS... by Olmy's+Jart · · Score: 5, Informative

    From the advisory: "Receipt of a specially-crafted dynamic update message to a zone for which the server is the master may cause BIND 9 servers to exit. Testing indicates that the attack packet has to be formulated against a zone for which that machine is a master. Launching the attack against slave zones does not trigger the assert."...

    So an obvious workaround is to only expose your slave DNS servers and to not expose your master server to the Internet. That's part of "best common practices" isn't it? You have one master and multiple slaves and you protect that master. Come on, this is pretty simple stuff. Just simple secure DNS practices should mitigate this. Yeah, if you haven't done it that way to begin with, you've got a mess on your hands converting and it's easier to patch. But patch AND fix your configuration.

    1. Re:Only effective against MASTERS... by raddan · · Score: 4, Insightful

      Because lots of people don't want intruders being able to affect the actual zone data in case an outward-facing DNS server gets compromised. Using SSH to transfer zone data is much easier and more secure than BIND's own zone transfer mechanisms (e.g., you can automate and schedule them), and you don't have to worry about zone transfers through firewalls. Troubleshooting all the weird crap that can happen between different DNS daemons all supposedly doing regular AXFRs is a real pain in the ass. SSH makes life easier.

      If having a DNS machine on the Internet that thinks it is a master really is a mistake, when then, BIND9 is a piece of shit. This is the most straightforward thing a DNS daemon should be asked to do.

      Nowhere in BIND's manual does it say people have to use BIND in a master/slave setup.

  5. For goodness sake upgrade.... by syousef · · Score: 4, Funny

    ...to Windows! DOS is just so 80's and 90's it's not funny.

    (Suggested mod: +1 funny)

    --
    These posts express my own personal views, not those of my employer
  6. djb by dickens · · Score: 4, Funny

    Somewhere I think djb is managing to both smile and raise his eyebrows simultaneously.

  7. Re:Ain't what it used to be.... by palegray.net · · Score: 4, Insightful

    Because modern-day admins don't know how to restart a service?

    Oh, wait, these are fellow Linux "admins" we're talking about...

    --
    512 MB RAM, 20 GB disk, 200 GB transfer, five datacenters. $19.95/month.
  8. Re:At least someone agrees that BIND 9 had issues. by profplump · · Score: 5, Informative

    Recent versions of BIND (8+) are not terrible to administer, and have much more reasonable data files. Older version were *really* nasty, and had a data file format so complicated that we invented a dedicated zone-transfer mechanism just so people could send DNS data to each other.

    And while djbdns uses an unconventional admin system with lots of environmental variables, that's a one-time setup (that is probably done in large part by your package manager) and the actual data files are dead-simple -- plain text, one record per line, can do DNS lookups at build time, can concatenate files, etc. There are valid complaints to be made about djbdns, but I don't think "difficult to wrangle" is one of them.

  9. Always do a reboot test ... by ZeekWatson · · Score: 4, Insightful

    If you're running a serious server you should always do a reboot test after installing any software. I've been burned many times by someone doing a "harmless" installation only to find out 6 months later a critical library was upgraded with an incompatible one (a recent example is expat 2.0) and the server doesn't boot like it should.

    Always reboot! Even with the super slow bios you get in servers nowadays it should only take 2 minutes to be back up and running.

  10. OMG... by Garion911 · · Score: 5, Interesting

    I reported a bug *very* similar to this back in Oct, and only now its coming to light? WTF? I submitted this back in january and it was rejected. Ah well. Here's my page on it: http://garion.tzo.com/resume/page2/bind.html

    --
    Slashdot is like Playboy: I read it for the articles
  11. Re:Interesting by Minwee · · Score: 5, Funny

    It is now.

    This vulnerability also gives the three people running DJB DNS a much needed opportunity for some smugness.

  12. Re:Interesting by kriebz · · Score: 5, Funny

    I was under the impression they had smugness to spare.

  13. iptables to the rescue by kju · · Score: 5, Informative

    For a quick "fix":

    iptables -A INPUT -p udp --dport 53 -j DROP -m u32 --u32 '30>>27&0xF=5'

    Will block (all) dnsupdate requests.

  14. Re:All versions of Bind 9? by tygerstripes · · Score: 5, Funny

    But it's a DOS vulnerability!!! Sheesh, read the title...

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    Meta will eat itself
  15. Re:It's because it works, & I believe in every by ShakaUVM · · Score: 4, Funny

    My approach isn't stupid in regards to that. Free? That's a "pretty good price", wouldn't YOU say? And, you're also FREE to customize it, & thus, YOUR PERSONALIZED VERSION OF A CUSTOM HOSTS FILE, JUST GOES ALONG WITH YOUR PERSONALIZED SPED UP & SAFER VERSION OF THE INTERNET... &, just as YOU see fit & like, easily. Notepad.exe for instance? My gosh - lol, just "does wonders" here, on this account... lol!

    Are you the ghost of Billy Mays?