QOTW #34 – iMessage – what security features are present?

2012-09-07 by . 0 comments

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Two weeks ago, a phishing vulnerability in the text messaging function of Apple’s iPhone was discovered by pod2g. The statement released by Apple said that iMessage, Apple’s proprietary instant messaging service was secure and suggested using it instead.

Apple takes security very seriously. When using iMessage instead of SMS, addresses are verified which protects against these kinds of spoofing attacks. One of the limitations of SMS is that it allows messages to be sent with spoofed addresses to any phone, so we urge customers to be extremely careful if they’re directed to an unknown website or address over SMS.

This prompted a rather large interest in the security community over how secure iMessage really is, given that the technology behind it is not public information. There have been several blog post and articles about that topic, including one right here on security.stackexchange –  The inner workings of iMessage security?

The answer given by dr jimbob provided a few clues, sourced from several links.

It appears that the connection between the phone and Apple’s servers are encrypted with SSL/TLS (unclear which version) using a certificate self signed by Apple with a 2048 bit RSA key.

The iMessage service has been partially reverse engineered. More information can be found here and here.

My thoughts – Is iMessage truly more secure?

Compared to traditional SMS, yes. I do consider iMessage more secure. For one thing, it uses SSL/TLS to encrypt the connection between the phone and Apple’s servers. Compared to the A5/1 cipher used to encrypt SMS communications, this is much more secure.

However, iMessage still should not be used to send sensitive information. All data so far indicates that the messages are stored in plaintext in Apple’s servers. This presents several vulnerabilities. Apple or anyone able to compromise Apple’s servers would be able to read your messages – for as long as their cached.

Treat iMessage as you would emails or SMS communications. It is safe enough for daily usage, but highly sensitive information should not be sent through it.








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