CCC Create a Rogue CA Certificate

t3rmin4t0r writes "Just when you were breathing easy about Kaminsky, DNS and the word hijacking, by repeating the word SSL in your head, the hackers at CCC were busy at work making a hash of SSL certificate security. Here's the scoop on how they set up their own rogue CA, by (from what I can figure) reversing the hash and engineering a collision up in MD5 space. Until now, MD5 collisions have been ignored because nobody would put in that much effort to create a useful dummy file, but a CA certificate for phishing seems juicy enough to be fodder for the botnets now."

Comments

Re:from the ... dept?

[TypoNAM]

I hate replying to myself, but if anybody hasn't noticed that CmdrTaco has been trying to tell us something and by this article he has apparently given up:

Alan Cox Leaves Red Hat
Posted by CmdrTaco on 10:11 AM -- Tuesday December 30 2008
from the bet-wherrever-he's-going-he'll-have-electricity-and-heat dept.

The Fight Over NASA's Future
Posted by CmdrTaco on 08:15 AM -- Tuesday December 30 2008
from the still-no-power-at-my-house dept.

Storm Causes AT&T Outage Across Midwest
Posted by CmdrTaco on 08:55 AM -- Monday December 29 2008
from the guess-who-this-includes dept.

So he's without power and worse no internet at his home, aww poor CmdrTaco. Somebody please think of the slashdot editors! Anybody got a spare generator and fuel? ;)

Re:Why trust the PKI?

[fastest fascist]

Using that would probably be more hassle than your average user is willing to put up with. A bigger wtf is, in my opinion: Do so many banking services really rely on a single login/pass combo per user for authentication? When banking security comes up here, I see people worry about having their login+pass revealed, which makes me think that's the only verification their banks use.

My bank at least also uses a one-time pad system, namely a numbered list of 100 pre-generated codes. So I log in using a username and pass, and then to actually do something with the on-line banking system I'm asked to provide the code that relates to a randomly chosen number between 0000 and 0099. A code can only be used once. So basically if the phishing site manages to get hold of a few numbers from a user's passcode list, the chances are still pretty slim they'll be able to do anything with them.

Of course, if they scam hundreds of people, they will get a few successes, but not very many.

CA's using MD5

[xaosflux]

FTA, the following common CA's are still using MD5.

RapidSSL
C=US, O=Equifax Secure Inc., CN=Equifax Secure Global eBusiness CA-1

FreeSSL (free trial certificates offered by RapidSSL)
C=US, ST=UT, L=Salt Lake City, O=The USERTRUST Network, OU=http://www.usertrust.com, CN=UTN-USERFirst-Network Applications

TC TrustCenter AG
C=DE, ST=Hamburg, L=Hamburg, O=TC TrustCenter for Security in Data Networks GmbH, OU=TC TrustCenter Class 3 CA/emailAddress=certificate@trustcenter.de

RSA Data Security
C=US, O=RSA Data Security, Inc., OU=Secure Server Certification Authority

Thawte
C=ZA, ST=Western Cape, L=Cape Town, O=Thawte Consulting cc, OU=Certification Services Division, CN=Thawte Premium Server CA/emailAddress=premium-server@thawte.com

verisign.co.jp
O=VeriSign Trust Network, OU=VeriSign, Inc., OU=VeriSign International Server CA - Class 3, OU=www.verisign.com/CPS Incorp.by Ref. LIABILITY LTD.(c)97 VeriSign

Re:its only the CA's that use MD5 so the question

[gclef]

It's in their slides. As of 2008, there were some big names still using MD-5:

RapidSSL
FreeSSL
TrustCenter
RSA Data Security (!)
Thawte (!)
verisign.co.jp

Re:its only the CA's that use MD5 so the question

[perp]

If I understand the CCC's paper correctly, as long as *even one* of the CA certs trusted by the browser uses MD5, it is possible (with considerable effort) to create an intermediate CA cert that can be used to sign a cert for any FQDN, say paypal.com. Then with a little DNS poisoning, the user is directed to an https site, with a correct domain name and (if the user looks, not bloody likely) a perfectly good certificate that looks like it was signed by a cert that was signed by a cert trusted by the browser.

You don't have to create many rogue certs, all you have to to is create one rogue intermediate CA cert that can sign as many certs as you like, all of which will be accepted with the default browser config. This is what the CCC has done.

Re:Alright this Internet is ruined

[Alrescha]

"I wonder how broken the intarwebs would be to me if I simply deleted all the MD5-based root certificates from my box? Would I even notice?"

I think a better idea would be to simply delete all the certificates from your box (CA certs included!). Then start marking individual web certs as trusted after you inspect them yourself.

A.

Re:No weakness

[Just Some Guy]

Maybe it's my naivety, but wouldn't a hash have to be of infinite length to be able to be used in a way that guarantees no collisions?

That's what I thought he was saying at first, but it's not. For an n-bit hash, the birthday paradox says you'll need to try an average of (n/2) bits to find a hit. The problem with MD5 is that you can find collisions in much fewer than 2^64 attempts. So sayeth Wikipedia:

On 18 March 2006, Klima published an algorithm[9] that can find a collision within one minute on a single notebook computer, using a method he calls tunneling.

So yes, all fixed-length hashes will have an infinite number of collisions. It's just that some hash algorithms make it a whole lot easier to find some of them.