Thursday, May 5, 2011

Some observations on the rekey of encrypted.google.com...

(This is a fairly technical post about monitoring changes in PKI infrastructure. Unless that sentence interests you, you probably don't want to read further.)

Since the Comodo CA issue I've been playing around with some of the PKI monitoring infrastructure including Perspectives and the Google Certificate Catalog. So when I heard that encrypted.google.com was rekeyed today, I decided to see what those monitoring infrastructures saw. A couple things surprised me.

First, I happened to have a browser window open to encrypted.google.com from the previous day when it was still using the old certificate. So I saved both the old and new certificates. From the certificates it was clear it wasn't just a new certificate for the same key, but a new key (along with a update of the validity period from 2/2011-2/2012 to 4/2011-4/2012).

Then, I looked at Perspectives, and it showed the new certificate (94:47:cd:b3:15:94:94:0c:f5:fd:5c:1b:b7:3c:ee:ce - the blue below with the purple being the old certificate) as just starting to be seen, no surprise there.








But, looking a little more carefully at the individual notary responses, while two notaries had either not seen it yet or just seen it in the last day, the other two have been seeing the new certificate for a while. hostway.ron.lcs.mit.edu saw the new certificate briefly back in April:

Key = 94:47:cd:b3:15:94:94:0c:f5:fd:5c:1b:b7:3c:ee:ce
 start: Tue Apr 26 02:28:11 2011
 end  : Tue Apr 26 14:28:07 2011
 start: Tue May  3 14:28:41 2011
 end  : Thu May  5 02:28:55 2011
And mvn.ron.lcs.mit.edu:8080 has been seeing it on and off for a week like clockwork:

Key = 94:47:cd:b3:15:94:94:0c:f5:fd:5c:1b:b7:3c:ee:ce
 start: Fri Apr 29 14:12:06 2011
 end  : Sat Apr 30 02:12:06 2011
 start: Sat Apr 30 14:12:05 2011
 end  : Sun May  1 02:12:06 2011
 start: Sun May  1 14:12:06 2011
 end  : Mon May  2 02:12:11 2011
 start: Mon May  2 14:12:18 2011
 end  : Tue May  3 02:12:20 2011
 start: Tue May  3 14:12:17 2011
 end  : Wed May  4 02:12:23 2011
 start: Wed May  4 14:12:22 2011
 end  : Thu May  5 02:12:25 2011 
Then I went and queried Google Certificate Catalog:
$ dig +short 20115245c15b7650f11e23985f117728cc8dcdb2.certs.googlednstest.com TXT
"15079 15098 19"
It has seen the new certificate for 19 days. If you do the math, the first day it saw the certificate works out to be April 14th, which is the day after it was issued (according to the certificate itself). So either it is clued into the issuance, or Google uses the certificate internally for a while before the world sees it.

So what does this mean? If this rekey is any indication, it means these things don't happen in a clean binary manner. Different parts of the network may see new certificates before others, and maybe for short spurts cutting back and forth between new and old. Looking at the detailed responses from Perspectives, previous changes for encrypted.google.com also show a similar bouncing back and forth (particularly with hostway.ron.lcs.mit.edu). This is turn means that certificate checkers using these infrastructures are going to have to be tolerant of this sort of noise during a change over.

Also, looking at Perspectives long term data for encrypted.google.com, it looks like a change happens every two months or so (note, one can't tell from this if they re-key or just create a new certificate):

Thursday, April 28, 2011

Sony PSN: Compromised security questions...

I am not a fan of security questions. My big criticism is that they turn an innocent fact about you into a shared secret - you now have to remember that the street you lived on in first grade gets you into your webmail account and not blog about that favorite childhood memory.


Now with the recent Sony Playstation Network compromise, it has raised an even bigger problem with (suspected in this case, they aren't sure) compromise of security questions. What do you do if your password questions get compromised at a site?

First, you probably have no idea what answers you even gave. The idea behind these questions is that you remember the answers naturally, so you don't need to write them down. So you probably have no idea now what questions you were asked and what answers got leaked.

Second, even if you did somehow know what answers you gave Sony (perhaps you signed up two weeks ago and you have a great memory), do you remember all the other sites you gave the same answers to? Time to go site to site checking (except, back to my first point, you probably don't remember what answers you are checking for).

Third, let's say you remember all that. These answers about you have been compromised and you can't change them - it's your history! This is a problem shared with biometrics, once your fingerprint gets out, you're stuck with just having nine left. Once a fact about you is known, you just have to know not to use it anymore as a secret.

So, security questions just went from bad to worse in my book.

My suggestion, fill in random strings (I use a random password generator or "slap on the keyboard"). Write your password down in a good password program like Password Safe or KeePass or use the password saving feature on your browser (I suggest setting a master password if you do so). Or if you do forget your password, most sites will still have some way you can get your password reset the old fashioned way through customer support.

Some interesting work on security questions:

And finally xkcd:
 

Thursday, March 10, 2011

Registration for 2011 CACR Higher Education Cybersecurity Summit now open

Date: Monday, April 11
Time: 8:00 a.m. - 5:00 p.m.
Location: University Place Conference Center, IUPUI

The Indiana University Center for Applied Cybersecurity Research cordially invites you to attend the 2011 Higher Education Cybersecurity Summit. This year's summit will take place on Monday, April 11, on the IUPUI campus near downtown Indianapolis.

The summit will offer a variety of sessions of interest to security, policy, and privacy officers as well as cybersecurity practitioners. There is no cost to attend the summit.

Sunday, February 13, 2011

My new position at IU CACR

Late in January I started my new position at Indiana University's Center for Applied Cybersecurity Research(CACR) as Deputy Director. I'm excited about this opportunity in that I'm joining a great existing team and working with CACR's Director, Fred Cate, who is internationally renown policy and pricacy expert. CACR has a existing education and outreach program that includes an annual cybersecurity summit (coming up again this year on April 11th, save the date) and a unique video-based cybersecurity education program for the general public called SecurityMatters. It is also a pleasure to work closely with staff at IU's Pervasive Technology Institute and the researchers in the informatics department that I've collaborated with remotely over the years.

On top of all that, the position returns me to Bloomington, where I grew up. Though I admit, it's strange coming back home after 22 years away.

My primary contribution to CACR will be to develop and lead a technical applied cybersecurity program to compliment the existing CACR outreach activities and cybersecurity research activities at IU. More on that to come as plans firm up over the coming weeks.