An Iranian hacker has stepped forward to claim responsibility for the SSL certificate hack against Comodo, providing an insight into how the high-profile hack might have been pulled off.
The lock-picker – who claimed he had "1,000 times" the experience of any hacker or programmer – asserted that after compromising Comodo's partner in Italy (GlobalTrust.it and InstantSSL.it) he was able to generate bogus SSL certificates for Skype, Yahoo, Windows Live, mail.google.com and addons.mozilla.org. These forged certificates created the means for others to pose as the targeted websites in man-in-the-middle or phishing attacks. The approach also cleared the way towards preventing users from installing censorship-circumvention Firefox extensions, at least in theory.
A total of nine certificates for seven domains were issued during the breach, which occurred on the evening of 15 March. The incident only became public a week later, after browser makers had issued an update, and long after the offending digital certificates had been revoked.
The incident sparked a debate about about how digital certificates are issued and revoked.
Mozilla, while praising Comodo for quickly revoking the certificate, criticised the firm for placing too much trust in its resellers: "The practice of issuing certs directly from the root eliminated some possible steps we could have taken to mitigate the problem. We are concerned about the amount of trust Comodo seems to have placed in RAs whose network security they did not oversee."
Comodo last week admitted that an affiliate registration authority, which it didn't name beyond saying it was based in southern Europe, had been hacked as part of an assault that it traced back to Iran. It suggests that the level of expertise that featured in the attack indicated it might be state-sponsored in some way.
However the hacker who stepped forward to claim responsibility for the attack claimed he had acted alone and was not affiliated with the Iranian Cyber Army, a Iranian government affiliated hacking cadre. The Iranian Cyber Army was previously known for an DNS hijack attack against Twitter and a DNS records hack against Chinese search engine Baidu that redirected surfers to a counterfeit (defaced) page back in January 2010.
The Comodo hacker said that he had set himself the goal of compromising the SSL root certificate system. After finding the RSA algorithm that underpins the security of the system too hard a nut to crack, he said he then began to look at the security of Certificate Authorities (CAs), later hitting on a Comodo partner in Italy as a weak link in the chain of trust that underpins the digital certificate system.
He discovered that InstantSSL.it provided application interfaces that allowed developers to submit certificate signing requests. Looking further, he reportedly discovered that plain text login credentials were used as part of this Certificate Signing Requests (CSRs) submission process, a howler that allowed him to forge countersigning signatures for digital certificates.
The hacker posted portions of what purports to be the offending library (TrustDLL.dll) to pastebin in order to substantiate his claims. These coding snippets included programming routines for authentication that appeared to rely on an unencrypted password.
It's very difficult to verify the claims beyond saying that the scenario is plausible and fits Comodo's explanation of the sequence of events, especially since the websites of GlobalTrust.it and InstantSSL.it have each been pulled down for repairs.
More commentary on the latest chapter of the Comodo-gate saga, including screenshots featuring the offending code snippets and the hacker's rather inflated claims, can be found in a blog post by Sophos here. ®