DigiNotar is a Dutch "Internet Trust Provider" running a Certificate Authority (CA),  selling SSL Certificates and digital signature solutions. DigiNotar had recently been bought by VASCO.  On August 30, 2011, DigiNotar/VASCO reported that DigiNotar detected on July 19th, 2011 an intrusion into their CA infrastructure, "... which resulted in the fraudulent issuance of public key certificate requests for a number of domains, including Google.com. " In the meantime we know that so far the known number of fraudulently created certificates is beyond 500 and it concerns domains like windowsupdate.com, microsoft.com, the Tor anonymization network, CIA and MI6. An interim report describing the first results of a forensic investigation conducted by the experts from Fox-IT, headed by it's founder and CEO J.R. Prins and released on Sept. 5th, 2011, found out that many Certificate Authorities managed by DigiNotar, including the PKI CA Overheid, where the Certificates for the Dutch Government are created, had been penetrated by hackers with root permissions. Besides the already mentioned Overheid CA the Fox-IT report mentions the CAs of the Dutch Federal Ministry of Justice, the Koninklijke Notariele Beroepsorganisatie CA (maybe the CA where digital certificates for the Dutch Notaries have been issued?), Renault Nissan Nederlands, Technical University Delft and many others, which were compromised. DigiNotar now is under control of the Dutch Government.

So far, one rogue certificate issued for the www.google.com domain has been misused by Iranian hackers to perform man-in-the-middle attacks mainly against co-patriots using Google Gmail to write and read emails. Note: the rogue certificate itself is not yet enough to run this kind of attack. The hackers additionally need access to the DNS system in order to deviate Internet traffic from the real Gmail server to a different one. In a country like Iran this of course is not a problem.

As each use of a certificate causes a verification call to the CA, which had released the certificate, the number of such attacks can be counted precisely (OCSP responder traffic). Between July 27 and August 29, 2011, 300,000 Google Gmail sessions had been hijacked. The very very sad thing about this information is that during the period of attack DigiNotar did know that they had been hacked, but they kept it secret. This is not the kind of trust a trust provider should provide. Considering that Iranian hackers may at least be supported by their government, as such hacking would provide the government with intelligence about the political opposition in their country, the trial to keep this "accident" private may cause Iranian dissidents to face sanctions from their governments.

Beyond the obvious aim of the attack to control Iranian internet outside Iran, there also may be some revenge involved, answering the virus attacks against the Iranian atomic plant in Bushher. A real cyberwar, so to say, with DigiNotar being a (indeed very weak) piece of the western world Internet security backbone called PKI. One more piece, as it has not been the first attack against PKI. In March this year Comodo, another Internet Trust Provider, had been victim of an attack, where somebody compromised a user account to create 9 rogue certificates. It seems that both attacks had been conducted by the same hacker or group of hackers, as he/they left the same message on the servers ("Janam Fadaye Rahbar" - which means something like "my life for the leader"). Furthermore, there just appeared a message on pastebin, which seems to have been posted by the hacker(s):

"You know, I have access to 4 more so HIGH profile CAs, which I can issue certs from them too which I will, I won't name them, I also had access to StartCom CA, I hacked their server too with so sophisticated methods, he was lucky by being sitted in front of HSM for signing, I will name just one more which I still have access: GlobalSign, let me use these accesses and CAs, later I'll talk about them too..."
So, there is more to come and we should now start to think about the consequences that can be drawn from the fact that CAs can be compromised at any time. Is PKI as secure as we have been made to believe, even from governments? Maybe, as a starter, have a look at this more than 10 years old article from well known security expert Bruce Schneier, which I kind of referenced in my headline: "Ten Risks of PKI: What You're not Being Told about Public Key Infrastructure". Much of what he wrote is still true, and some things have gone even worse. While Schneier had asked in his "Risk#1: Who do we trust, and for what?",  who authorized the CA to behave like an authority in granting authorizations and while he found the term "trusted" to be misused in the case of CAs, today such authorizations are in place. By law. By legal document. In the case of DigiNotar, the Dutch government even used the hacked infrastructure to run that one root CA, which should be the last one to be hacked before a country loses its independence.

In his "Risk#9: How secure are the certificate practices?", Bruce Schneier states:

"Certificates aren’t like some magic security elixir, where you can just add a drop to your system and it will become secure. Certificates must be used properly if you want security."
PKI leaves plenty of space for insecure practices. Although there have been several incidents now suggesting that we have a serious problem with bad practices at trusted (sic!) third parties, it may be the vast majority that are safe and indeed trustworthy. Sure? It's unfortunately not for us to decide, which CAs are trustworthy and which not. This decision is being taken fo example by the browser manufacturers, because it is them who manage the lists of trusted certificates, which are part of each browser. Wouldn't it be better if the trust decisions are left to the users, without any influence? DigiNotar has now been deleted from all those lists, so that you will get a warning if a server uses a certificate issued by them. Comodo has not been deleted. What is it that makes the difference?

So, PKI seems to not be the trust model that will last forever, at least not without some fundamental renovation. But what can we do in the meantime? As a trust provider: don't make the management part of your CA software available in the cloud. That would not be good for you. As a client, you should have a business continuity plan telling what to do if your Root CA is compromised, even or especially if that Root CA is managed by a 3rd party.

Venafi's Calum MacLeod just sent out a mail proposing 4 steps to make you survive a compomised root CA:

  1. Have more than one, so that you can just throw away the compromised one.
  2. Organizations must have an accounting of all the CAs that they use as third party trust providers
  3. They must have a complete inventory of the owner and location for each certificate in the enterprise. This often numbers in the thousands and even tens of thousands or more in Global 2000 organizations.
  4. Every organization must have an actionable and comprehensive plan in place to recover from a CA compromise. The time to recover needs to be measured in hours, not weeks or months.
Even if these proposals come from a key and certificate management vendor - they aren't wrong at all.