Appelbaum said that Iranian authorities confront activists with online evidence of their alleged crimes during interrogations. "They regularly show those who are arrested data on their Internet traffic," said Appelbaum.
Abdulhayoglu said there was no proof that anyone in Iran was at risk because of the disclosure delay.
The only certificate that Comodo saw actually in use was one of the three assigned to Yahoo, login.yahoo.com. "Only one certificate was seen live, and that was just a test," said Abdulhayoglu.
According to Comodo, the fake Yahoo site went offline shortly after the company revoked the phony certificate.
Comodo has not been able to confirm if the attackers were actually able to obtain any of the other eight certificates before they were revoked, Abdulhayoglu admitted. He also declined to share details of the attack, including the reseller whose account was used to acquire the certificates or how the hackers obtained the reseller's username and password, citing ongoing law enforcement investigations.
In any case, there was no reason to disclose the theft before browser makers could patch their software to block the stolen certificates. "There's no point in disclosing unless there's a remedy," Abdulhayoglu said. "Hence the patches, which make everyone secure."
Several times Abdulhayoglu said the delay was necessary for "responsible disclosure," the practice of withholding information about security vulnerabilities or problems until a fix is ready.
Google, Microsoft and Mozilla have each issued updates that add the nine stolen certificates to their browsers' blacklists.
But Appelbaum argued that no one -- other than the attacker who had the stolen certificates -- would have been harmed if Comodo and others had broken the news earlier.
"The only people that can attack using [the certificates] are those who have them," said Appelbaum. "I can't launch an attack, I am only able to detect an attacker using [the certificates]."
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