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."

Comments

April Fools Idea

[DarkHelmet]

Oh man, this article gave me an idea. Too bad it's a couple days late, or else it would have made a *great* april fools for the workplace here.

1. Change the company's DNS server here to map google.com to a private machine here on the network.
2. Create a frontend on the internal machines here that looks exactly like google.com
3. Map the internal IP addresses on the network to specific people here.
4. Inject specific "spooky" messages into the search results based on the IP address of the querying machine. Examples would be like: "How about looking at some pr0n, Mr. Bridges?" or "You really should have that bald patch looked at, sir."
5. April Fools! HA HA!
6. Look for a new job.

Oh well, you only live once.

Re:April Fools Idea

[Cruithne]

7. Profit!

Re:April Fools Idea

[sjames]

Just keep in mind, In Soviet Russia, a beowulf cluster profits by imagining 50 year old South Koreans pouring hot grits down your pants.

IRC

[Wizy]

Anyone who has been on irc for over 8 years remembers when DNS cache poisoning first started showing up (about 97.)

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 /dline ipmask :reason."

It has been a well known problem since way back then and it has still not be dealt with in any real way.

internet rash

[Cruithne]

following a rash of active DNS poisonings

Damn internet rashes, they're the worst. Remember, dont surf without protecting your board. :/

More color-coded warnings?

[loqi]

I give it two years until the sight of a rainbow fills me with abject terror and confusion.

Re:More color-coded warnings?

[oneiros27]

Kryten: We must take action. Be bold, positive, decisive. I suggest we move from blue alert to red alert, sir. Cat: Forget red! Let's go all the way up to brown alert! Kryten: But there's no such thing as brown alert, sir. Cat: You won't be saying that in a minute. And don't say I didn't alert you!

Red Dwarf, Series 8, Episode 1.

Re:More color-coded warnings?

[mmkkbb]

*KABOOM*

Arrr, an attack! Matey, fetch me red shirt! Can't let the men see me bleedin' if I get hit! ...

*KABOOM*

Arrr, that was a close one! Fetch me brown pants too!

Re:More color-coded warnings?

[Fjornir]

RIMMER: Go to blue alert.
LISTER: What for? There's no-one to alert - we're all here.
RIMMER: I would just feel more comfortable if I know that we're all on
our toes 'cos everyone's aware it's a blue-alert situation.
LISTER: We all are on our toes.
RIMMER: May I remind you all of Space Core Directive 34124?
KRYTEN: 34124. "No officer with false teeth should attempt oral sex in
zero gravity".
RIMMER: Damn you both, all the way to Hades! I want to go to Blue Alert!
LISTER: Ok, ok.
.
.
.
LISTER: Too small for a vessel... maybe some kind of missile.
KRYTEN: It's impossible to tell at this range. Whatever it is, they
clearly have a technology way in advance of our own!
LISTER: So do the Albanian State Washing Machine Company.
RIMMER: Step up to red alert!
KRYTEN: Sir, are you absolutely sure? It does mean changing the bulb.
RIMMER: There's always some excuse, isn't there?

Let's Kill The Golden Goose

[ackthpt]

Sure, internet click-thrus generate money, but when they get so invasive and destructive, they'll drive people way from the internet. I can't imagine any advertiser likes that idea.

Worse, perhaps, is that all these problems may encourage some horrible proprietary internet standards to arise, claiming safety from ad/spy/malware, phishing, etc. and all the cattle have to do is sign up, abandoning the old internet.

Re:If this is such a big deal...

[Wizy]

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

Re:How does this work?

[Tony Hoyle]

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.

Question

[Ryosen]

I've been using Opera for 6 years now and I'm a little confused.

What is "malware"?

Re:Question

[OnceWas]

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.

Re:More reason to use Firefox

[bcmm]

I bet that malware is Internet Explorer-specific.

Yes. It's so great to use a web browser that doesn't rely on Microsoft technology like DNS...
Oh, wait...


Idiot.

Re:colored alerts

[delta_avi_delta]

You know the British secret service use color coded bikini's for terror alert levels. Black-Special Bikini has got to be the coolest alert level around :)

Re:windowsupdate.microsoft.com?

[Anonymous Coward]

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.

Re:windowsupdate.microsoft.com?

[Dejohn]

I believe that all Windows Update patches are digitally signed, so this spoof might be harder to pull of than it would initially seem

Re:How to stop DNS cache poisoning

[Wizy]

Did you run the warez server? I know that guys name.

Djbdns - immune to DNS cache poisoning (?)

[bad_outlook]

Anyone using Djdns? I've set it up on my home network server running FreeBSD to provide dnscache for all my boxes within 192* and thus far it's working perfectly. From Djdns' security page, it says that it's impervious to DNS poisoning:

• "dnscache does not cache (or pass along) records outside the server's bailiwick; those records could be poisoned. Records for foo.dom, for example, are accepted only from the root servers, the dom servers, and the foo.dom servers."

  "dnscache is immune to cache poisoning."

Djbdns

While I don't think I'm in the clear because of this, I feel better protected from the (unwashed ;)) internet. Anyone care to comment, please do, as I've just started using this and want to know how effective it is.

bo

The most frightening part...

[loopsandsounds]

If you read down the SANS presentation you come to this:

The following list shows how far-reaching this attack proved to be. The list is a small, categorized excerpt of the 665 domain names from his site (with my short notes) that were being re-directed to hostile web servers. It is very important to note that e-mail, FTP logins, HTTPS sessions, and other types of traffic were also being re-directed to the malicious servers. We do not believe that the attacker was reading e-mail or collecting passwords, but we have no conclusive proof to assert either theory.

Totally browser/machine agnostic attacks, no user intervention. If you look at the names of the sites, many of them are financial institutions! And all of those victims that click okay everytime they get an "invalid certificate" message. Be afraid, very afraid.

Re:How does it happen?

[Anonymous Coward]

There are a few ways. Off the top of my noggin:

• If your target DNS server is running Microsofts DNS server, on W2K SP 1 or 2 (this may have been patched, I dunno), you can poison DNS using an alias. It's simple. You have to have control of a zone (say realzone.com) and a DNS server. You create a zone on your dns server under the name you want to poison, say example.com. Your DNS server thinks it is authoritative for the example.com zone. Next you create a host record in example.com that points to a host you control. In your real zone (realzone.com), you create a CNAME record for a host like spoof that points to hostname at example.com, like www.example.com. Then you point your local stub resolver at the target DNS server (most DNS servers will resolve for anyone by default). When you try to lookup spoof.realzone.com, the target DNS server will find your dns server. Your dns server will see that spoof.realzone.com is a CNAME for www.example.com and look that up. Since it thinks it is authoritative for example.com, it will ask itself, and returh that IP address to the target DNS server. Now it is in the targets DNS cache. Anyone who tried to resolve www.example.com from that DNS server will get the IP address of the host you defined in the example.com zone. Spoof!.
• Another way is to sniff the traffic of the target DNS server and when it tries to resolve a host name, feed it the result of your choosing before the recursive query finishes. The first response wins, generally.

There are probably other ways, but it isn't hard.

The bottom line, DNS is an untrustworthy system.

Re:simple

[fimbulvetr]

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...

Re:How does it happen?

[jon3k]

Unprotected DDNS (dynamic dns registration, Microsoft loves this one)

And also you can feed a slave server your own zone, based on the nameserver configuration, it will work (very rarely).

No

[temojen]

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.

Yet another example of Windows messing up

[Paradox]

Ahh, Windows. People use it for servers too.

From TFA:

Basically, the UNIX-based stuff has been secure against cache poisoning
for quite some time, but there may always be a bug or design flaw that
is discovered. We are not quite sure why Microsoft left a default
configuration to be unsecure in NT4 and 2000. (Exercise to reader:
insert Microsoft security comment/opinion/joke here, but keep it to
yourself).

The worst part about DNS cache poisoning is that it affects DNS nodes underneath it in the hierarchy. So if you're below a Windows DNS that gets attacked, you yourself may be subject even if your local DNS is in fact secure.

Oh, and fear caching http proxy servers that touch DNS servers that get poisoned. They can keep the bad data around for a long time.

SANS vs. the rest of the security community.

[tsu doh nimh]

Washingtonpost.com is running an interesting story about how SANS is really the only major player in the security community that is making any noise about this.

...(snip..)

...."But here's the rub: Symantec Corp., which maintains tens of thousands of "sensors" at various points around the Internet to pick up signs of Internet attacks, said it isn't seeing anything out of the ordinary with DNS attacks.

Dave Kennedy, director of research services at Herndon, Va.-based Cybertrust (formerly TruSecure), had this to say about the reports: "It's been nearly a month since SANS started ringing their alarm bells over this and maybe I'm not looking in the right places, but I'm grading this as hype until I see some independent support."

Russ Cooper, Cybertrust's chief technologist, put it this way: "In my opinion, our industry's creditiblity comes from further reports from multiple sources. We run a very large operation worldwide, and we've looked for signs of what SANS is talking about, but we're just not seeing it."

All of this may seem like an academic debate to those who claim to have been victimized by these attacks.

On March 24, Ken Goods, a computer network administrator for a mid-sized insurance company in Idaho, learned that the company's DNS servers had been attacked when employees began reporting that their Internet browsers were being redirected to a Web site hawking generic Viagra and other prescription drugs.

"I kept trying to go to Google to research the problem, but even though my Web browser said I was at Google.com, the only content that showed up was this pharmacy site," said Goods, who asked that his employer not be named because the company is still in the process of fixing the problem.

John, a systems administrator for a major U.S.-based manufacturing company, said a DNS poisoning attack like the one SANS described last month led to Internet problems for roughly 8,000 of his company's 20,000 employees. John asked that his surname and employer's identity be omitted from this story because the company is trying to determine if it is still vulnerable.

In the following weeks, several more attacks ensued that sent victims at John's company to Web sites advertising penis-enlargement pills.

Marcus Sachs, director of SANS and a former White House cyber-security adviser, said the security industry's response to their alerts about the attacks has been little more than a collective "yawn." Meanwhile, Sachs said, it appears the Internet connection at a San Diego hotel where the organization is holding its annual conference this week also was hit with a poisoning attack (the guy at the hotel who handles Web site security hasn't yet returned my calls.)

"People are waving this off and saying 'This is nothing new, we've seen this kind of thing before, let's move on.' But the consensus amongst the SANS folks is that something doesn't feel right here, and that there's more to this story than meets the eye. We feel like there's something deeper going on here, but the fact is there are not a lot of people out there in the security industry who are willing to dig deep and get to the bottom of this."

Re:SANS vs. the rest of the security community.

[httptech]

I wrote this article about the source and motivations of the attack (also mentioned by the Washington Post blog), so SANS is not the only security organization talking about it. But there's a reason you're not hearing alarm bells all over.

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/

Re:How to stop DNS cache poisoning

[menscher]

If all DNS records had 0 lifetime, the load on the core DNS servers would cause them to melt. Nice if you want a DDoS, not so nice if you want the internet to work.

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.

Re:Funny How Easy this is to prevent

[McSpew]

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:

DNS cache pollution protection is enabled by default in Windows 2000 SP3 and later.

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.

Sebben Alert Level Update

[ewhac]

...the SANS Internet Storm Center has raised their alert level to Yellow following a rash of active DNS poisonings.

ATTENTION: ALERT LEVEL UPDATE. The authorities at SANS (Sebben-Affilliated Network Security) have issued this network alert update:

The DNS cache poisoning alert has been upgraded from "Yellow" to "Blackwatch Plaid." Repeat: DNS cache poisoning alert level is now at Blackwatch Plaid.

Available information does not yet justify a further upgrade to alert level "Moving Pictures."

And for everyone's safety and security, and to preserve our way of life, SANS is taking a drastic step and installing a network monitor. Just one. For safety, security, and omniscient, unblinking information gathering of everyone's activities.

:-),
Schwab

Re:More reason to use Firefox -- Yeah

[gru3hunt3r]

DNS poisoning is not new. Using it for fraud is new. Defending against it (if you're Google) is difficult, but not impossible.

I swear -- Technical people need to stop addressing these problems with solutions that are technically elegant but unrealistic.
Yeah, lets secure all the nameservers on the Net! sure that'll work. Hell, we've only been doing DNS poisoning attacks for what? 12 years or so? hey well at least we finally got sendmail secure. Doh!

The only way we're going to be able to stop bad guys is to start having applications that use more than one protocol to verify integrity AND start building in stronger indepedent crypto behind the scenes making it much much much harder to spoof. You don't have to change the whole protocol stack we just need to share more information across protocols. Right now, when you compromise one protocol, you own the box. Aiiee!

I'm actually happy this happened -- because I've felt the Net needed a big overhaul for a while. My parents can't safely use the Internet, neither can yours. And all us gunslingers who could keep them safe are too busy securing our damn nameserver, and dealing with joe jobs to do anything about it. The solution requires a more comprehensive look at the problem.

If the bad guys are specifically targeting google with DNS poisoning, it's reasonable to assume it will undermine peoples faith in Google. (ATTENTION FLAMERS: YES, I am aware the request was hijacked long before it got to Google -- but the end user won't be because they don't have a clue what DNS stands for or how it works).

Seriously - your mom/dad would take away from an explanation of DNS hijacking was "Go to google, get a virus" (read the previous article posted earlier today about how people don't understand technobabble) ..

Does anybody else besides me find this whole thing incredibly ironic? People will see Google as being the problem, even though it's almost definitely Microsofts fault. Damn.. sucks to be Google. (Okay, yeah.. honestly i'd love to have Googlesque problems, but also the Googlesque resources to solve them!)

Anyway I think this sort of article hopefully illustrates to Google why they need to start promoting a secure browser WHICH isn't subject to malware attacks such as IE really is in their best interest -- and although it has a minimal cost impact to them, it has a huge long term impact to the net community. Honestly, I believe if Google offered a "safer" online experience -- i'd put my parents on it in a second, I think everybody here would too. I don't trust Yahoo, MSN, Ask Jeeves, etc. or any of those companies with the tender care of my parents Internet experience.

I say Google - rather than just "firefox", because if Google put Gbrowser on their homepage you know it'd have a 30% usershare virtually overnight -- maybe more. They install the google toolbar, it transmits information about where you're surfing to google -- BUT it also checks with Google to make sure you're at a "safe site" --

OKAY so you want a real example -- how about a simple one -- why not a modified robots.txt with an entry that included a list of the valid IP's for the SOA for your root domain for the next 30 days. Boom, they already pick up robots.txt -- BUT now they can authenticate that the DNS wasn't posioned using google toolbar. Sexy huh?

I've got lots of ideas like this -- there are probably 5 things sites could *OPTIONALLY* do, that merge application stacks -- but at the same time it would make it necessary for a phiser to compromise MULTIPLE hosts, across MULTIPLE protocols -- thereby making it *statistically* impossible.

(NOTE: If I seem brilliant it's only because i'm standing on the shoulders of Giants. I love how SPF uses DNS to authenticate mail servers -- it's non-intrusive, but an illustrative example of the types of solutions that we as a technical community need to solve problems)

Re:How does this work?

[Stuwee]

From memory, classic DNS poisoning goes something like the following:

1. Pick any DNS server which isn't authoritative for the domain which you wish to poison with the IP of your choosing. Something like your ISP's DNS server will work nicely.
   
2. Send a legitimate DNS request to the server for a domain which is authoritative under a server you are in control of, and which your choosen server (and any in-between it and your own server) won't already have in its cache.
   
3. When the request for the domain comes into your server, you have the sequence number which originated from your target DNS server. The idea with this sequence number is that your reply to the originating server contains the number, and hence the server knows which request is being replied to. Here is where the vulnerability comes in.
   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).
   
4. Next up, make a request to your target server for the domain which you want to take control of. For this to work, your target DNS server must send out a further request for this domain. Since you have an idea of the sequence number which has been sent out with this request, you can now start flooding the target DNS server with false replies.
   
5. The ultimate goal is that you will hit the correct sequence number with your false reply before the legitimate reply comes in, hence poisoning the DNS. Further requests to your target server within the record timeout (which you may specify yourself in your false replies, so they can last quite a while) will be replied to with a cached version containing your poisoned IP.
   
6. Watch the requests come in for the content to your own IP, serve up appropriately.
   

DON'T CLICK LINK

[suwain_2]

Don't click that link! I clicked it and got a really nasty porn site.