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DNS Cache Poisoning Spreads Malware
Gamma_UCF writes "As of April 4, 2005 the SANS Internet Storm Center has raised their alert level to Yellow following a rash of active DNS poisonings. The infected DNS servers are re-directing users from popular sites such as Google or American Express to malware infecting advertising sites. According to the ISC presentation on the attack, it is believed to be linked to known spammers and malware distributors. The full presentation of information up until this point can be found here."
Anyone who has been on irc for over 8 years remembers when DNS cache poisoning first started showing up (about 97.)
/dline ipmask :reason."
This is a quote from the "IRC Operators Guide" written in 8/97:
"DNS spoofing is a relatively new hit these days on IRC. You'll generally find spoofs one of two ways - you're watching the connections (usermode +c) and an unusual hostmask appears, or a user reports one. The first thing to do is to get the user's IP address (/stats L nick), and check to see if the DNS lookup matches the IP address. If it doesn't, you know you have a spoof. With this information, you can KILL the spoof, and when it reconnects, see where the real host is and issue a K-line (which won't stop them from spoofing again, but will prevent them from signing on *without* spoofing). Some servers have the capability of D-lines, which allow you to ban by ip mask. A D-line will prevent the client from connecting at all, regardless of whether they try DNS spoofing or not. If the server supports the DLINE command, you can do
It has been a well known problem since way back then and it has still not be dealt with in any real way.
We have. This has been a known problem since early 1997. It is well documented in the IRC community (admins and coders.)
Documents like this one from 1997: http://www.cs.rpi.edu/~kennyz/doc/unix/dns.spoof
It's where you have an insecure server and someone manages to modify your zone file externally. It really shouldn't be possible any more... all dns servers ship secure by default, and any admin that makes such a configuration change should be fired on the spot.
usually its done by flooding a dns server with carefully crafted false replys based on known previous requests from the server.
or by taking advantage of servers that listen to extra information that they really shouldn't listen to in a reply.
with both methods the aim is to trick the dns server into cacheing your false response for its clients.
Has anybody tried to redirect windowsupdate.microsoft.com? That could potentially install malware at massive privilege levels and therefore impossible to remove. And it's done automatically.
Automatic updates that are not signed and verified will not install.
I believe that all Windows Update patches are digitally signed, so this spoof might be harder to pull of than it would initially seem
There are probably other ways, but it isn't hard.
The bottom line, DNS is an untrustworthy system.
The separation between DNS Server and DNS Cache is very clever. This is a point that even BIND must take care.
This is a DNS server issue, not a client issue.
Suppose you visit citibank.com often. citibank.com is at 192.168.0.1 (It's an example). If the dns server you normally query has been poisened, it could potentially give you 10.0.0.1 (that's an example too). 10.0.0.1 could be a quick 0 day citibank look alike setup in korea with the sole purpose of grabbing your username,password,acct number, etc.
The real citibank.com would never know that this happened, and there is a real chance the person who ran your dns server wouldn't know either.
There are no 10 minute preventative measures one could do to protect themselves on this one, outside of using a known good dns resolver. Even then, you have to know the the dns server the resolver uses is good...
Opera (or Firefox) isn't immune to phishing attacks. How would you know you're giving your banking info to a phony site that looks exactly like your own bank's login screen? Especially if the domain name is correct?
I assume SSL would catch some of this, but not all.
DNS poisoning is creepy, since it's browser/OS agnostic.
Laugh while you can, monkey-boy.
The "no" part is that virtually nobody does this. All the protection in the world is useless if you don't use it. Further, the protections that do exist (such as those I mentioned) get redesigned a little too often, making wide-scale rollouts a real problem.
Routers are another key part of the infrastructure where there is plenty in place that COULD prevent poisoning, but where actual use in the "Real World" is limited. If DNS ever does improve, then scammers may well simply shift to poisoning router tables to achieve the same results.
The resources spent on producing quality and security are phenominal. The resources spent on actually putting these into practice can barely be detected with the best tunneling electron microscopes.
It's a small world and it smells funny; I'd buy another if it wasn't for the money; Take back what I paid (SoM)
Start by clicking the "HERE" in the article and, oh, wow, there's a whole report on how it happens!
- AMW
The article is about DNS Cache poisoning, not DNS spoofing. In DNS cache poisoning you're effectively telling the victim's DNS server to query your (fake) server for all of a class of requests (ie *.com), instead of the one it should be querying. DNS spoofing only tries to fool reverse lookups.
DJB has talked about it at least as far back as November 2001.
libresolv problems,talking about poissoning
Je ne parle pas francais.
Ever heard of a monoculture? It's dangerous. That's the primary reason Microsoft has so many security issues. To guard against this, the DNS infrastructure of the internet is intentionally made to be heterogeneous. They use different DNS software on different operating systems as much as possible.
Top security consultant? Doubtful. More likely an AC trying (and failing) to impersonate someone with a clue.
Damn, if only I had checked the "turn on security" box!!
From MSFT (http://support.microsoft.com/kb/241352/EN-US/)
How very wrong you are.
Win2k DNS automatically turns on "secure cache against pollution" in SP3+. Read about it at http://support.microsoft.com/kb/316786/EN-US/. Specifically, you're looking for this quote:
Win2k DNS servers with this feature turned on are STILL vulnerable. I know because my DNS servers are configured this way and I began to suffer from the DNS poisoning on Thursday of last week. It took me until Friday to get a real handle on what was happening. Slashdot ignored my submission of this story back then. They were too busy jerking around with April Fool's stories.
Wrote about this today in his blog:
http://blogs.washingtonpost.com/securityfix/
He provides some background and comments from companies effected by the attacks. And he offers some opposing views from SANS and Symantec Corp. on whether this is a serious concern or not.
Basically it comes down to this - the attack was used to hijack searches for pay-per-click engines. It was done in the most obvious way and got a lot of attention. If they had been smarter, they would only have redirected defunct sites instead of cnn.com and the rest of the .com TLD.
Now that the cat is out of the bag, people are watching for the traffic, so a second, more malicious attack probably won't see nearly as much success. So there's no reason to panic - it's a 4-year-old vulnerability as it is, and fixed by a simple registry edit. Most people will be unaffected by it.
-Joe
Joe Stewart, GCIH
Senior Security Researcher
LURHQ http://www.lurhq.com/
If you bothered to RTFA, you would also know that the problem is with Windows NT servers (that should have been taken offline years ago or upgraded to Linux) and Unix machines that were compromised (probably also not up to date). No upgrade in bind will help you on that one and NT is famous for being full of holes. Don't sweat it though, "experts" are dated quickly in this field.
Encourage people to keep their systems up to date, patched and watched would be better. Do integrety checking - like with tripwire. Check it every day. Even then you can still get burned, happens to the best of us.
Now, how do I get one of those fancy $450/hr jobs (No moving to Boston!)?
Earlier versions of BIND use sequential sequence numbers in each request; nowadays pseudo-random numbers are used. What we're really after here is the next sequence number, or at least an idea of what it might be. In the case of sequential numbers, you have a rather small range of next sequence numbers. If your pseudo-RNG isn't cryptographically secure, it's possible to guess the next number in the sequence (for which you might want to make a few legitimate requests to your target server to observe the sequence).
That seems fairly reasonable. I don't think you're really protected from poisoning, unless "poisoning" only applies to certain kinds of DNS spoofing. Specifically, first note the exceptions to the djbdns security guarantee:
Specifically, his forgery page points out that a spoofing attack based on the birthday paradox can still work... although probably tens of millions of packets are required. This page, which I think I got off slashdot before, uses the TCP sequence-number guessing tools to try to attack it. It's probably not quite as secure as djb estimates, but probably still in the millions. They don't seem to have actually run numbers for the randomized-port plus randomized-id, so it's unclear whether they actually attacked that thoroughly.
So there's no reason to panic - it's a 4-year-old vulnerability as it is, and fixed by a simple registry edit. Most people will be unaffected by it.
Ah, but here's the rub: It's not fixed by a simple registry edit. Win2k SP3 and SP4 are "secure" by default. I'm running Win2k SP3 and SP4, and I was bitten by this. The MS articles I initially found about cache poisoning didn't mention that SP3 and SP4 are secured by default, so I went and inserted the registry setting and restarted my DNS servers. The next day, the poisoning was back. That was when I discovered that SP3 and SP4 are secured by default, and that was when I realized that this problem is more serious than most people realize.
I tried to publicize what I'd learned on Friday. I submitted the story to Slashdot, where it was rejected because it wasn't an April Fool's prank. I submitted it to Russ Cooper's NTBugTraq, where it disappeared into the ether. Imagine my consternation when Russ Cooper was quoted in today's Washington Post security blog saying that nobody was seeing it. I wrote to Russ immediately after seeing that quote and assured him that I was seeing it and I had posted to his list, but the post had not been approved by him.
I'm pissed off because very few people are taking this seriously and well-meaning people such as yourself are dismissing it as a minor vulnerability that's easily remedied with a registry edit. This attack is not remedied by inserting a registry entry and restarting the server--it affects servers that are supposed to be immune.
You probably would have been better off sending your findings to handlers@sans.org - you're the first person I've heard say that the fix doesn't work, and since SANS hasn't updated the information, I presume they haven't heard about it yet either.
.com label in the Authority section is technically a subdomain of any .com domain they may be querying, the SecureResponses key doesn't reject it. This would be a fairly big deal (not too big, you realize, since most of the world doesn't use MS DNS servers) that would require some independent testing in order to convince MS to change their stance (and fix the problem for real).
Despite the fact that your experience contradicts MS and CERT-CC, I'm willing to accept the possibility that because the
Any chance you captured some of the traffic as it was occuring on your would-be immune servers? Because the poisoning attack from abx4.com is over now, so it will take a bit of work to recreate it in the lab without those servers to conveniently supply the test packets.