Google recently reported the possibility of a Man-In-The-Middle (MITM) attack using fraudulent SSL certificates issued by DigiNotar. The attack affected people logging into Google's popular email services from Iran, and google has responded by rejecting all the Certificate Authorities operated by DigiNotar. We now know that Google is not the only possible target of these bogus DigiNotar issued certificates. Rather DigiNotar certificate signing services, used to create a foundation of trust, had been used maliciously to create many fraudulent SSL certificates. Given DigiNotar's critical role as a certificate authority, how could this have happened? What does it mean for the perceived "trust" we've become accustomed to in our daily usage of the internet? Given the attackers success with DigiNotar, the Comodo incident back in March, and the use of digitally signed malware, this appears to be a growing trend. How can we stop this from happening again and what can you as an internet savvy user do to protect yourself?
The breach of DigiNotar BV has been confirmed through an Interim Report released by Fox IT on the fifth of September, as well as by a flurry of online activity by major Internet browsers. In the report titled “Operation Black Tulip”, Fox IT mentions previous penetration test results from an audit company DigiNotar BV regularly utilized stating “A number of servers were compromised. The hackers have obtained administrative rights to the outside webservers, the CA Server “Relaties-CA” and also to “Public-CA”. Traces of the hacker activity started on June 17th and ended on July 22nd.” According to the report, a total of 531 fraudulent certificates were issued by the attackers.
The report goes on to mention some other key dates and pieces of information:
- 128 rogue certificates digitally signed by DigiNotar detected on July 19th, revoked immediately.
- 129 rogue certificated digitally signed by DigiNotar detected on July 20th, revoked on the 21st.
- No Date Given - DigiNotar implements detection mechanism for invalid serial numbers through OCSP.
- July 29th, a *.google.com certificate was discovered that had not previously been discovered, revoked immediately.
- August 30th, Fox IT called in to investigate the incident, and provide mitigation strategies going forward.
According to all reports, the first public mention of this serious breach was not by DigiNotar BV, but rather a user in Iran who was presented with a certificate warning when trying to access https://mail.google.com. His suspicion, as well as other users, drew the attention of Google, who offered the first mitigation strategy, and action against DigiNotar BV by revoking all certificates signed by the CA. Several browser companies immediately followed suite, including Microsoft and Mozilla. Apple has remained close lipped on the issue, most likely due to the fact a bug in the Safari browser will not allow the DigiNotar certificates to be properly revoked.
Right now Google Chrome, IE and Mozilla Firefox have updated their Certificate Revocation Lists (CRLs) to blacklist the DigitNotar signed certificates. Claims by ‘ComodoHacker’ to have access to four additional CAs have prompted Globalsign to stop issuing certificates until they can verify that their infrastructure is secure. And lastly, the Dutch government has stepped into take over DigiNotar’s operations, after Fox IT’s report stated that the official Dutch government CA, PKIOverheid, also run by Diginotar, may also have been compromised.
Still, while the investigation remains ongoing, there are many questions that need answers.
- Why did DigiNotar BV not notify the proper authorities regarding this breach nearly a month ago?
- If DigiNotar had notified browser makers immediately, would the follow on invasions of privacy in Iran have happened?
- How on earth were their most valued, and critical assets so readily available to the outside, and unpatched and outdated?
- What requirements, policies, standards, and governance do Certificate Authorities need to adhere to, to remain a trusted CA? For that matter, is there any governance?
- SSL is the only real technology at this time meant to provide true data integrity, and protection to it’s users on the Internet. What happens when we cannot count on the CA’s to provide prompt and proper notification, so that we may remain protected? The fact remains that SSL relies on an imperfect trust relationship between Certificate Authorities. Moxie Marlinspike’s presentation from Black Hat 2011, SSL And The Future of Authenticity, details a more distributed alternative.
Okay, so now that you understand the scope of the problem and how bad this is, what can you do to protect yourself?
- Make sure you browser is up to date
- Utilize browsers who are taking the necessary steps to protect the users
- Remain vigilant when browsing secured websites, if you suspect something is amiss, notify the sites abuse or security department immediately with as many details you can document
This and similar past events covered by Cyber Squared where fraudulent certificate signing was involved , makes one wonder if the foundation of Internet trust we have become accustomed, can be trusted in itself. Although scary, I hope that this serves as a wake-up call that CA's are targets for sophisticated cyber threats, and that there is currently a lack of policies, standards, and governance that the certificate authorities must adhere to to maintain their "trusted" status.