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Ten Percent of DNS Servers Still Vulnerable
maotx writes "Even with the uproar caused by the recent DNS attacks, a recent study shows that roughly 10% of 2.5 million DNS servers show that they are still vulnerable to DNS cache poisoning. To put that a little bit more in perspective, of that 10% discovered, 230,000 were identified as potentially vulnerable, 60,000 are very likely to be open to this specific type of attack, and 13,000 have a cache that can definitely be poisoned." From the article: "The use of DNS cache poisoning to steal personal information from people by sending them to spoofed sites is a relatively new threat. Some security companies have called this technique pharming."
This is strikingly similar to the Cisco OS debacle, where a patch had been available for some time, yet Admins failed to patch their hardware on their own. Yes, it's a pain in the ass to take your network down, but look at the alternative...Hacked!
"Simplify, simplify, simplify!" Thoreau
230,000 were identified as potentially vulnerable, 60,000 are very likely to be open to this specific type of attack, and 13,000 have a cache that can definitely be poisoned.
Okay, let's have it for unclear writing!
Seriously, what does this even mean? Of the 250,000 that are vulnerable, 230,000 are vulnerable, 60,000 are vulnerable, and 13,000 are vulnerable.
Okay, that clears it up.
This is not suprising at all especially considering the history of DNS and it's mainframe components. They will always be vunerable, especially for people who do not have the proper PPS setup. I wouldn't be suprised if it's more then 10%.
It's tacyo YO!
with almost all of the potentially vulnerable ones they only said really that 73k of them were vulnerable to something... and only 10k of those "definately" were.... 73k = 2.92% The onlther 230k might not have been vulnerable at all, they just think there's a chance that they might be. This, ladies and gents, is called sensationalism...
The same person also does Qmail Rocks. Of course djbdns and qmail is much more secure than bind and sendmail.
Fight Spammers!
Some security companies have called this technique pharming.
Phor phuck's sakes! I've had enough of this phreaking 733T-speak from the phucking security compaines! It was original with phreaking; it was mildly amusing with phishing; now it's just annoying.
Why not just leave the terminology as "DNS cache poisoning" and be done with it?
[/rant]
"I don't get it." -- ObviousGuy
...or for any other DNS exploits, for that matter?
Any good tools to (or sites to help) check for those?
A lot of these new vulnerabilities have the "phat" theme as dictated by the industry's leading security researcher/rapper Prompt Master Chizzy. Expect an RFC soon on the new naming convention.
Exec 1: We at our company want a an attack name with attitude. It's edgy, it's "in your face." You've heard the expression "as easy as stealing from a baby"? Well this is an attack which makes it "eezzay!". Consistently and thoroughly.
CEO: So it's speculative, huh?
Exec 1: Oh, God, yes. We're talking about a totally outrageous paradigm.
Exec 2: Execuse me, but "speculative" and "paradigm"? Aren't these just buzzwords that dumb people use to sound important? [backpedaling] Not that I'm accusing you of anything like that. [pause] I'm fired, aren't I?
CEO: Oh, yes.
CEO: The rest of you start thinking up a name for this funky attack. I dunno, something along the line of say... farming, only more dangerous and 1337.
Exec 1: So, Pharming okay with everybody?
All: [reclining in their chairs] Yeah...
Someone's gotta speak up for the poor admins. Not all of them really are morons for not patching. There are cases where the patch breaks more than it fixes. In these cases, it's often more economical to just leave the vulnerability there (hey, at least you know about it) than to try to patch it. SQL Slammer caused some serious problems with IIS because the 'patch' for the bug it exploited was part of a large update that required a lot of man-hours to clean up after. Of course, there are plenty of moron admins out there too, I wouldn't want them to feel overlooked... >.>
Government's view of the economy: If it moves, tax it. If it keeps moving,regulate it. If it stops moving, subsidize it.
Especially since the pharmaceutical companies have a much better (and prior) claim to the name for using organisms to produce medicines.
DNS Cache Spoofing is not the only nasty trick available to DNS hackers; There is a (still) relatively unknown vulnerability afecting the vast majority of nameservers today, and one that is not easily resolved by patches alone.
Check out my paper about this, its called DNS Cache Snooping, and allows for a bunch of interesting tricks. It afects most of DNS Server/Cache combination implementations and is triggered by an extremely common misconfiguration, one that allows for the whole of the internet to use a given DNS server as their primary DNS server.
Luis Grangeia
DNS cache poisoning doesnt stop at tricking people out of their money. At defcon Kaminsky also showed how it can easily be used to do things like email misdirection, which I think is much more of a big deal.
Can I get a list of these vulnerable servers so I can.. umm... see if I'm on it and patch my systems? Yeah.. that's it.
You create your own reality - Leave mine to me.
I'm confused about this one too. This is what I THINK is going on with this exploit. Hopefully, someone who ACTUALLY knows will correct my mistakes. :)
One of the possible ways to set up a DNS server is as a 'forwarder'. This means that it doesn't do lookups itself, but rather passes all DNS requests to another machine, gets replies, and then sends replies to the clients. One reason you might do this would be to distribute DNS load in a big ISP; you have a few machines that do the actual outbound DNS determination, and then the cache ripples back to the servers that are actually talking directly to the clients. DNS is fairly low-load, relatively speaking... this architecture would date from when everyone was deploying 50Mhz machines as servers. I'll call the local BINDs 'caching' servers, and the one doing the actual lookups on the internet the 'point' server.
So in and of itself, this architecture isn't a problem. But one of the features of the DNS protocol is that any server can send back more data than what was actually asked for, even data that is totally unrelated to the main query. Caching BIND servers by default trust their point server. And, when functioning as a point forwarder, BIND4 and BIND8 apparently just pass along queries they receive without checking them. The point BIND assumes that the caching BINDs are checking, while the caching BINDs assume the point BIND is checking, and the packet never gets checked for sanity at all.
So Joe Hacker snoops around... he tries to find DNS servers on your network. Once he finds one, he queries it for a name in a domain he controls. (or he initiates a connection to a webserver on the same machine, which may cause the same DNS lookup). He watches for the request to his DNS server coming from a DIFFERENT machine. That often indicates a forwarder configuration.
So he waits for his cached info to expire, and does it again... except this time, his reply packet includes extra information, "Oh, by the way, www.microsoft.com is on joes.evil.server.here." If BIND4 or BIND8 is the functioning as the master lookup in a forward configuration, it just passes along the packets it receives. And when BIND is in a SLAVE configuration, it just trusts what it gets from the forwarder. So suddenly, your whole network is connecting to joes.evil.server.here instead of www.microsoft.com. And if it doesn't work, oh well, next DNS server... this is a very low-profile attack. You have to really be LOOKING for it to be able to see it.
Apparently, the workarounds are A) don't use a forwarder configuration. There's no real need for this anymore, even a cheap 1ghz machine with a gig or so of ram will serve tens of thousands of clients. B) if you MUST use a forwarder, use BIND9 (or, presumably, DJBDNS) as your 'point' machine. BIND9 does sanity checking when it's on point.
Hopefully I got this right. I haven't been paying much attention to this before, because I (rightly) didn't think it affected me. If I'm wrong, PLEASE correct me, I hate to spread misinformation.
We were fighting people doing this 10 years ago. Some of the second-gen (meaning they used at least some technology rather than outright and direct use as is) usenet spammers and flooders and email spammers were doing it. The new uses to which this is being put are news, but DNS poisoning is not. IIRC, the icq.net servers were so compromised after having been bought out by AOL and put to new use.
I'm betting there's still a problem with admins that don't want it fixed, because they have given permission, or worse, for their servers to be used thus with some plausible deniability. Arranging this was the origin of the second-gen spammers.
"I may be synthetic, but I'm not stupid." -- Bishop 341-B
Sure. But if you use forwarders who run BIND4/BIND8 you've still got the same problem. If you're connecting directly to the root servers you're contributing to their unneccesary overload and bypassing the heirarchal nature of the DNS system.
BD Phone Home!
Shameless plug. Like you weren't expecting it.
The news.com article is short on specifics about what the thousands of servers are actually doing, but there's better info at Dan Kaminsky's site: http://www.doxpara.com/
t
This powerpoint presentation has some details: http://www.doxpara.com/Black_Ops_Of_TCPIP_2005.pp
Why isn't this said when a microsoft issue comes about, and there has been a patch for some time... it's always bad microsoft!!!
Now that's it's Bind, it's the admin's fault?
I read
Your sig is an urban legend. See snopes for details.
General Relativity: Space-time tells matter where to go; Matter tells space-time what shape to be.
I think there should be an internet user license program. I know it smells like some way of identifying people and all that, but it doesn't have to be any more than a driver's license does at present.
I'm thinking of something along the lines of a radio operator's license with different levels and qualifications and all that. Then people who are said to be administrators of web hosts and stuff like that would be required to posess a certain level of knowledge (and potentially a certain level of pay?) and ability. If it is shown that they do not demonstrate the proficiency required for some reason, then their license should be revoked or downgraded.
Furthermore, certain levels of internet "safety" and "security" ratings should be given to all software, firmware and hardware products that run on the public internet. The consumers can be better aware of the quality of the products they use on the internet. (Examples might include a rating for MSIE having a lower security rating than Firefox because of that whole ActiveX thing... or a Linksys firewall/router giving the users behind it a certain rating of security over a Windows box connected directly to the public internet.)
Not only would we be able to leverage these sorts of licenses and ratings to have a better and safer internet, but we would be able to have a more conscious set of consumers who just might be able to look at the label to determine that product A is better than product B. They will no longer need to get an education in how the internet works just to get their home computers on the net... and we'll be less likely to deal with all those spambots and zombies out there as well.
I love people who think DJB owes them something because he wrote some code. If you read some of his papers, he sure does have a big ego, but if you take a look at the papers and software he produces, it's pretty darn flawless. If you could produce unbelievably fast and secure code as quick as him, you too could get cocky.
That's what admins/geeks are. Think of the classic 'Hackers' movie, and the big admin with the password of 'God'. Admins love thier l33t Perl, C, TCL, Shell scripts because they do everything they need. We have contests as to who can make code that does something in the fewest number of lines (many references on Slashdot) and who can make the code decievingly complex (again many references).
DJB made something that fits with his views. He made it available to the public and people liked it so much they started to use it. The best part about DJBs stuff is that it does it's job and does it well.
I hear the big anti-qmail and anti-djbdns debate all the time about people who want tons of features in there. All of the features you can want are in patches, and patch collections that you can safely add. DJB has a mail system that does what he wants, and does it securely. He's not willing to accept patches into the mail distro because it taints its quality. That's his choice.
He wrote the code, he puts it up there. If you like it, use it. If you don't, avoid it. If you want features, make a patch for yourself or for others.
He's a smart guy who produced some damn good software that has a following for good reason. He doesn't want patched binary distributions floating around, as security issues in those reflect negatively on his word. As well, it keeps those who don't take the time to learn the basics of administration from operating misconfigured qmail installations. All good reason- I'd agree with most of it.
-M
when you see the word 'Linux', drink!
What the badguy actually does is:
- gets queried for www.badguy.com by target.com
- delegates authority for HIS nameservers to ns.yahoo.com, for example; so he says:
- www.badguy.com NS ns1.yahoo.com
- www.badguy.com NS ns2.yahoo.com
- ...
- ALSO includes fake mappings of the form:
- ns1.yahoo.com A 1.2.3.4
- ns2.yahoo.com A 1.2.3.4
- ...
- so target.com contacts "ns1.yahoo.com" at 1.2.3.4 and asks to resolve "www.badguy.com"
- since ns1.yahoo.com is *actually* a name server under bad guy's control (bad guy controls 1.2.3.4), ns1.yahoo.com returns how to get to www.badguy.com
- then in future queries for www.yahoo.com, the name server will ask 1.2.3.4 for the IP for www.yahoo.com and send that reply to the requestor
Much better explained hereAs DJB says, the "work around" is not to accept authoritative mappings (e.g. ns1.yahoo.com A 1.2.3.4) from anyone but yahoo.com.