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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."
Let's go make a new one.
I prefer teal CAs, myself. Or possibly burnt sienna CAs. Sometimes fuschia CAs.
It's ROGUE you dumbass.
Oh noes! What department of Slashdot did this article come from? Its the end of the world as we know it! ;)
This space is not for rent.
The commies are creating their own CA!! PANIC!!!
http://spamdecoy.net - free throwaway anonymous email - avoid spam!
Why does your bank not give you a compact disc with their public key on it when you sign up for an account?
Go green: turn off your refrigerator.
These certificates are at the basis of truth on secure websites. MD5 has been known to have vulnerabilities for a loooong time (2004 according to the link article). Why do not banking services keep up to date with the state of the art crypto ?
The Wise adapts himself to the world. The Fool adapts the world to himself. Therefore, all progress depends on the Fool.
some CA's use MD5 the question really should be which ones
they point to a rather doomsday scenario of having a problem with all SSL Certificate Authorities
this is not the case
only the ones that use MD5
so the question really is what is the list of SSL Certificate Authorities that do this ?
regards
John Jones
http://www.johnjones.me.uk
It's important to note that this sort of collision is not taking advantage of any of the known weaknesses in MD5, rather it's brute force.
This is just to head off the inevitable screaming of "MD5 is broken for everything anyway!!!".
I've had enough abrasive sigs. Kittens are cute and fuzzy.
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
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
I'm not familiar with the details of certificate use, but as far as the cryptologic component there seems to be a reasonable fix, that will not require any change from end-users or invalidate existing certificates (apart from changing the hash).
The attack is based on finding a hash collision between certificates A and B, having the CA signing A, and using the signature for B. If the CA were to make a small change to A before signing it the attack would be foiled, since it requires active participation from the CA.
Suppose the CA started to add a few random bits to each certificate before signing it. The applicant is told what these bits are, so that they can use the signed (modified) certificate to verify themselves to users. With just a few extra bits this would make the attack unfeasible. Does this make sense?
A lot of people in the twitterverse seem to think otherwise, but this is not a major breakage of the Internet. See my commentary at O'Reilly: http://broadcast.oreilly.com/2008/12/the-sky-is-not-falling-on-toda.html
That's a nice piece of work. I'm very impressed.
Practical conclusions:
I'll set fire to CowboyNeal. That kills two birds with one stone: fuel and food.
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.
There are two kinds of sysadmins: paranoids and losers. I'm both kinds.
Of all the industries that are slow to implement change in cryptographic practices, banking is by far the slowest. Part of this is bureaucratic inertia, part of this is lack of trust of newer algorithms until "proven" safe, and still part of this is reliance on legacy HSMs in their server facilities. Even the NSA has mandated a faster transition to better crypto (e.g. Suite B) than banking. Banking is still using 3DES instead of AES128, although for practical purposes brute-forcing 3DES at 112 bits of effective security isn't that much worse than AES' 128 bits. Banking won't move quickly unless someone starts stealing many thousands of high-profile accounts, but it'll be a bit like a buffalo stampede.
Still, it's mind-boggling that MD5 is still in use by anyone at this point given that it is susceptible to collisions. NSA Suite B is very clear that SHA2 256 is the minimum acceptable hash, and so it should be elsewhere regardless of your symmetric or asymmetric crypto. Back in the day when RSA512 was still used for PKI because of limited computing power, there might have been an excuse to stick to MD5. And yet, we all moved on to RSA1024 and RSA2048 because RSA512 was broken too. SHA2 is free, and it works. It really is time to move on from MD5 for all uses.
Funny enough that the entire security of the Internet as most users see it is based on the MD5 hash of the browser binary...
First, this issue is about banks (for instance) verifying themselves to the client, not the other way around, so not sure how OTPs and such figure into this.
Overall, between the drama over one of Comodo's trustee CAs handing out certs without verification (for mozilla.com no less) and this MD5 attack, there is a lesson on this for Mozilla:
Trusted CAs aren't the epitome of web safety. In fact, they are LESS safe than one of those "Invalid" (to use Mozilla's ill-chosen words) self-signed certificates under some circumstances.
I put the ranking of https safety as follows:
1. Any self-generated cert (even self-signed) which has been directly copied from the service provider (bank, etc.) and imported into the browser.
Though this is the most secure, it is a shame that the user may receive warnings from other Firefox users who visited the site about the cert being "Invalid", undermining confidence in this most secure method of using certs.
2. Any self-generated cert (even self-signed) verified by SHA1 fingerprint "out of bank" (e.g. letter or phone call or even email) then imported into the browser. Unfortunately the easiest method to initiate this procedure (visit the site, verify then click on a button to import) is now somewhat broken in Firefox and will quite inappropriately undermine the user's confidence in what is otherwise a very secure cert.
3. Relying on the browser-trusted CAs. Unfortunately there now many of them which are obscure even in the tech community, and some are sloppy and incompetent.
Wouldn't setting security.ssl3.rsa_rc4_128_md5 to false prohibit these kind of attacks?
Strange bunch of hackers. Don't expect some rouge students here, one is Arjen Lenstra, which is a well known figure in the security scene.
Very interesting to see that not only do they issue certificates using MD5 signatures (a very stupid thing to do) but they haven't even bothered to make sure that only leaf certificates can be issued. Or there are probably other CA certificates already issued under these root CA's, making matters even worse.
The article was very well written and thus easy to read. I'm only concerned about the recommendation of the authors to do nothing if you've been issued an MD5 certificate yourself. Doing nothing does not seem to be a very good advice. I would myself go to another shop and get a SHA-1 signed certificate (or even a SHA-2 signed certificate for those not concerned with low level browsers). At least your customers will know that there is no man in the middle due to the MD5 issue, and you show that you care for your clients' security.
Hopefully SHA-1 will hold up a bit longer, because last time I looked (a year ago or somewhere in that order), there were zero (0!) certificates that were self signed using SHA-2, which is not a good indication of the current state at all.
Gosh, that's the second CA I've disabled within Firefox just this week. Interesting times.
Good conclusions. You write that RapidSSL and FreeSSL should be pulled from IE and Netscape.
Interesting point about this is, that there is only approx 30 Trusted CA:s in Windows Vista. Compared to how many in XP? 80-100 or so?
Seems that some have already been pulled?
I joined two users too late.
And that is what was done.
Link
You are being MICROattacked, from various angles, in a SOFT manner.
You're on /. and you've actually seen panties?
Stop making shit up.....
"City hall" in German is "Rathaus" Kinda explains a few things......
note that the collision attack requires a bit of junk in the cert to make the hash be the same as for the original... this means the junk will not look like the rest of the cert. the rest of the cert is formatted and the collision noise will look mostly random. a simple test for unexpected randomness in the cert data (including Netscape comments) would reveal this sort of mischief. it just takes a bit of code on the browser to look for it. shouldn't even degrade browsing performance too much.
"If still these truths be held to be
Self evident."
-Edna St. Vincent Millay