Comodo has admitted a further two registration authorities tied to the digital certificates firm were hit by a high-profile forged digital certificate attack earlier this month.
No forged certificates were issued as a result of the assault on victims two and three of the attack, but confirmation that multiple resellers in the Comodo community were compromised is bound to renew questions about the trust model applied by the firm.
Comodo has previously admitted that the compromise of one of its partners in southern Europe on 15 March allowed a hacker to generate bogus SSL certificates for Skype, Yahoo, Windows Live, mail.google.com and addons.mozilla.org. These certificates were revoked hours after they were issued, but the incident only became public a week later after browser developers including Microsoft and Mozilla had published updates. The certificates create a means to mount convincing man-in-the-middle or phishing attacks.
Earlier this week an Iranian hacker claimed responsibility for the assault, claiming that he acted alone and naming GlobalTrust.it and InstantSSL.it as the targets of his assault. He published fragments of digital certificate programming interfaces on Pastebin to substantiate his claims. The presumed hacker also posted the forged certificate for Mozilla that he created for himself, as well as the associated private key for this certificates.
The miscreant also published what he claimed were tables from files on Comodo's database in a post on Tuesday, as further proof of his self-described elite skills against those who doubted his initial claims. He called on Comodo to come clean about the hack, the exact motives for which remain more than a little unclear.
Comodo has now discovered that two more of its registration authorities (also unnamed) were hit by the same attack. Robin Alden, CTO of Comodo, stated in a post to mozilla.dev.security.policy about the attack: "Two further RA accounts have since been compromised and had RA privileges withdrawn. No further mis-issued certificates have resulted from those compromises."
Alden said Comodo was in the process of rolling out two-factor authentication products to its resellers (registration authorities), as a safeguard against future attacks. this process is likely to take around two weeks. In the meantime Comodo has promised to review validation work by its resellers before issuing certificates, rather than trusting the whole process to its resellers.
Responding to criticism from Mozilla that Comodo should not have allowed its RAs resellers to issue digital certificates directly from the root, a practice that invalidated possible countermeasures to the attack, Comodo said it was changing its business practices to move away from this model. ®