iMessage flaw lets hackers see your photos and videos

21 Mar, 2016

Threat of iPhone backdoor "scares" researcher, who says Apple must get basic encryption right

Researchers at Johns Hopkins University have discovered an encryption flaw in Apple's iMessage platform that could allow an attacker to view photos and videos sent via the service.

The group was led by Matthew Green, an expert in cryptography and professor at the university's department of computer science, who had suspected a bug may exist after reading an Apple security guide in 2015, which described the encryption process.

Green alerted Apple's engineers to the potential vulnerability, according to The Washington Post. However, after a few months passed with no patch being issued, he and his research team decided to investigate it themselves.

Green told the Post he and his graduate students wrote software to mimic an Apple server in order to target a message being sent between iPhones that contained a link to a photo stored in Apple's iCloud server and a 64-digit key to decrypt it.

While the key's digits were hidden, the students were able to effectively use a process of trial and error to guess them by repeatedly changing a letter or number in the string. When it was correctly guessed, the phone would accept it, giving them incrementally more of the key until they had the full 64-bit string.

Referring to the ongoing court case between Apple and the FBI, Green told the Post: "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 backdoors to encryption when we can't even get basic encryption right."

All devices not running Apple's latest mobile OS, iOS 9.3, are vulnerable to the attack and, the researchers claimed, a modified version of the attack would work even on this operating system, although it would require the resources of a nation state.

Full details of the exploit will be revealed in a research paper to be published by Green and his graduate researchers once Apple has rolled out a patch for the bug.

Image credit: Kelvinsong (Own work) [CC BY 3.0], via Wikimedia Commons

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