Recently, a critical vulnerability has been discovered in iMessage by the researchers of John HopkinsUniversity. This flaw, if exploited, will allow a skilled attacker to decrypt photos and videos sent as secure instant messages via iMessage.
According to Apple, the flaw is fully fixed in iOS 9.3, while iOS 9 has a partial fix that will make it harder for someone trying to decrypt the messages. The Washington Post reports that the researchers at John Hopkins, notified Apple about the bug, and when iOS 9.3 is officially released they will publish their research. However, the research team has explained briefly how the vulnerability can be exploited to decrypt iMessages.
The researchers wrote a code that imitated an Apple Server to intercept a file. The encrypted message they targeted contained a 64-digit key code to decrypt the message and also a link to the photo stored on Apple’s iCloud server. They guessed the digits by repetitively changing a digit or a letter in the key and sending it back to the target phone. When they guessed a digit correctly, the phone accepted it. They repeated this process thousands of times.
“And we kept doing that, until we had the key”, Green said.
Computer Science professor Matthew D. Green said that he suspected the existence of a vulnerability in iMessage when he read Apple’s encryption process security guide. He alerted Apple at that time, notifying them that a vulnerability might exist in iMessage. When Apple did not fix the flaw, a team of students decided to exploit the vulnerability in practice. The professor said that existence of such a flaw is support for Apple’s position against the FBI.
“Even Apple, with all their skills — and they have terrific cryptographers — wasn’t able to quite get this right. So it scares me that we’re having this conversation about adding back doors to encryption when we can’t even get basic encryption right”, Green said.
Apple users should update their devices to iOS 9.3 as soon as possible. Otherwise, all of their Apple devices could still be vulnerable to the exploit that will allow attackers to access their encrypted files.