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IT Blogwatch

A Daily Digest of IT Blogs from Richi Jennings

Horrific DNS vulnerability now exploited

The sky is falling on IT Blogwatch: in which the theoretical DNS vulnerability of two weeks ago is now not-so-theoretical any more. Not to mention the pipetting system boyband (huh?)...

Robert McMillan realizes our worst fears:

Hackers have released software that exploits a recently disclosed flaw in the Domain Name System (DNS) ... Internet security experts warn that this code may give criminals a way to launch virtually undetectable phishing attacks against Internet users whose service providers have not installed the latest DNS server patches
...
The bug was first disclosed by IOActive researcher Dan Kaminsky earlier this month, but technical details of the flaw were leaked onto the Internet earlier this week .
...
The corporate users and Internet service providers who are the major users of DNS servers have had since July 8 to patch the flaw, but many have not yet installed the fix on all DNS servers. more

Glenn Fleishman adds:

Do you run domain name service (DNS) nameservers in your company? Not sure? Go check. Now. Really. I mean it. DNS is the glue that binds the Internet.
...
Kaminsky ... [and] Paul Vixie ... pulled together a secret meeting at Microsoft earlier this year that involved all major operating system and DNS server developers. Simultaneous work was performed to release patches all at the same time for every system.
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Visit the CERT page on the vulnerability to find what steps you need to take to ensure your users aren't vulnerable. more

Dan Kaminsky (for it is he) pens this ditty:

Patch. Today. Now. Yes, stay late. Yes, forward to OpenDNS if you have to. (They’re ready for your traffic.) Thank you to the many of you who already have. more

And Paul Vixie (the very same) flogs a dead horse:

As the coordinator of the combined vendor response, I've heard plenty of complaints, and I've watched as Dan Kaminsky has been called an idiot ... Stop complaining, we've all got a lot of work to do by August 7 and it's a little silly to spend any time arguing when we need to be patching.
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Please ... take the advisory seriously—we're not just a bunch of n00b alarmists, if we tell you your DNS house is on fire, and we hand you a fire hose, take it.
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News bulletin ... if your recursive nameserver is behind most forms of NAT/PAT device, the patch won't do you any good since your port numbers will be rewritten on the way out ... [So] move your recursive DNS to be outside your NAT/PAT perimeter, or enable your NAT/PAT device to be an ALG, or use TSIG-secured DNS forwarding when passing through your perimeter. more

Dr. Neal Krawetz despairs:

Patch now. Dan Kaminsky clearly found something -- some type of big bug that has been lurking in DNS. Even without knowing the details, it is clear that the fix needs to be applied.
...
One would think that every major ISP would be rushing to apply the fix. However, this does not seem to be the case. With half of the 30-day warning period already past, a surprisingly large number of ISPs are still vulnerable. In fact, of the 60 DNS servers I tested, more than half of them were still vulnerable. Considering that many of the "safe" DNS servers were not vulnerable prior to this situation, this means that far fewer than half of the large ISPs have even reacted to the notice. Here is the wall of shame so far. more

Kim Zetter is tired of being collated at the ends of lists:

Well ... the anticipated attack code to exploit the critical Kaminsky DNS cache-poisoning flaw is now in the wild (assuming there wasn't one already out there). Let's call it a .5-day exploit.
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System administrators who dragged their feet over updating their DNS servers have lost the race . . . so to speak. But that doesn't mean it's too late to patch your system. more

But bizitch can haz criticizm:

In case anyone is dumb enough to use a Microsoft DNS server as a authoritative internet DNS server - MS has released two lovely patches - KB951746 and KB951748.

The problem with this fix is that it turns the DNS.EXE daemon into a UDP socket grubbing whore. After the patch, the DNS.EXE daemon grabs no less than 2500 freaking UDP sockets.

This wreaks havoc on anything that - you know - needs UDP sockets on the same server. So far Zonealarm, Blackberry BES and Sphericall VOIP software all break with this "patch"

Stay tuned for more fun to come. more

And finally...

Buffer overflow:

Other Computerworld bloggers:

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Richi Jennings is an independent analyst/adviser/consultant, specializing in blogging, email, and spam. A 21 year, cross-functional IT veteran, he is also an analyst at Ferris Research. You can follow him on Twitter, pretend to be Richi's friend on Facebook, or just use boring old email: blogwatch@richi.co.uk.

Previously in IT Blogwatch:

What People Are Saying

Rate this
Rated +6
468 Votes

Too much talk, very little action

1. I don't care what OS you use as long as you patch it. Bash Windows, bash linux, bash Solaris, bash BSD, bash OSX Server all you like. You use what you can provide skilled technicians to keep running.
2. One of the writers (of another article on this topic) makes the mistake of saying that DNS server that is poisoned would be taken offline. Well, if that isn't a joke, I don't know what is. It has taken three years for the FBI to build a case against someone I know OF well enough to throw his butt in jail for committing actual crimes, not redirecting pokemon fans to a competing website. If you had competent writers on your staff, it wouldn't hurt.
3. ONE POISONED DNS SERVER doesn't really harm much in reality. DNS servers point to domains using tables of names and IP addresses. An analogy for you - if you are driving from Dallas Texas going to New York City, and along the way you pass through Denver Colorado, you should be able to figure out something is wrong. Guess what? DNS servers are only part of the system, did you all forget there are routers along the way that also have DNS functions? Maybe you also did not realize that most ISPs have a DNS cache and that is where the greatest vulnerability is, although this can be reduced to zero effect by redundant checks (most ISPs have two or more DNS servers each with its own cache).
4. I have known of this exploit (at least in theory) for over five years. This is not news. This is one company being highly irresponsible and my hope is that this has proven to be the most embarrassing moment for them, and the person who released the information.
5. The problem with "news organizations" even in the IT sector is that they latch onto what seems to be an interesting story, but the truth is that there isn't much to report here. A known (by too many it seems) exploit was published accidentally and before the (F)OSS community could take care of the problem. It would have been nice if they had sent an email to mozilla and opera first, dontcha think? Maybe the FBI (and NSA) also. Irresponsible reporting of an irresponsible release of information regarding a zero day exploit ...
6. For a company that focuses on security, how is it that they are the ones who end up releasing sensitive data? That would be like an Air Force Press Release with the Roswell crash info unredacted on the web for a few hours - pictures of little green (or gray) men and all! You can bet I won't be contracting them for services in the future.
7. This would have been an interesting story if it really applied on a global scale. It doesn't. THE ARTICLE ITSELF STATES ONLY LINUX DNS SERVERS ARE EFFECTED ONCE WINDOWS DNS SERVERS ARE PATCHED. That means BSD, OSX, Solaris, etc are not effected. So much for scripting vulnerabilities, huh? I guess maybe linux isn't so powerful after all ;-)

Rate this
Rated +18
430 Votes

Misinformed

Sadly, Mike, you're misinformed.

You can't have known of this exploit for over five years, because it did not exist five years ago.

Neither did can you have known of the vulnerability, except as a mere theory of an "impossibility" -- nobody had figured out how to take advantage of the small ID space.

Your point about ISPs running DNS servers is exactly the problem -- all these servers need to be patched, with few exceptions. As Dr. Krawetz points out, several big ISPs appear to be dragging their feet.

If anyone reading this is responsible for a DNS server, do your career a favor and ensure it's patched. Thanks.

Rate this
Rated +2
412 Votes

That specific exploit? No, however ...

My point wasn't articulated very well, but I feel you understood it. I could add to what I wrote above and let you form your own opinions on how much theft would occur from a DNS trick to a fake banking site - what about the SSL cert? There, I've done it. Well, unless we are talking about debian, right?

And when I say in theory, I mean that once I learned enough about computers, I knew it wouldn't be hard to misdirect traffic intended for a site. The how and why ... that is why I say there is grievous error in the initial release of this info. Keep dealing with specifics in public, and I will keep addressing the generalities. If idiot (my word) me has thought of it, why haven't sysops at ISPs? This gets to a second (ninth?) very valid point. If you don't have enough staff to maintain your equip and services, you had better hire more fast!

I could instead say that if Cisco Systems was a responsible netizen, they would have made sure this sort of thing was impossible. No, I laid the blame squarely where it should be. My published comments aren't really an attack on you, by the way. You have an editor, or should anyhow. A single editor strategically placed would have prevented this very public and very worrisome event until it got patched by everyone who needed to patch it.

Oh, and seriously - you think every effected linux box will ber patched? Not until there is a centralized repository for updates, and that would REQUIRE those who build the distros to be responsible and stop playing "my code is better than yours" games. Sure, a competent programmer can solve this problem in linux in about 15 minutes, but can we gurantee that everyone who uses a linux DNS server is a competent programmer? Or that they actually look for known exploits and search for solutions?

Rate this
Rated -3
391 Votes

Well, not exactly, IMHO

Addressing at least some of your points:

  • SSL won't help if the bank doesn't encrypt the initial logon page, as many U.S. banks fail to do (they only encrypt the form submission and subsequent pages).

  • Yes, this class of vulnerability is well-known, but the method is apparently new. Hence, this is a newly-discovered vulnerability. The vuln makes it "easy" to exploit.
  • People have thought of this before, yes -- that's why OpenDNS and others have been preaching randomized port numbers for ages. But nobody listened -- it takes a high-profile story like this to mobilize people.
  • My "editor" fires me at least once a week, as you may have noticed. But I'm still here -- does that tell you something? ;-)

Cheers,
richi.