Apple has implemented a series of short- and long-term defenses to its iMessage protocol after several issues were discovered by a team of researchers at Johns Hopkins University, according to a report published today (via PatentlyApple).
This attack is different to the one Johns Hopkins researchers discovered in March, which allowed an attacker to decrypt photos and videos sent over iMessage.
The technical paper details how another method known as a "ciphertext attack" allowed them to retrospectively decrypt certain types of payloads and attachments when either the sender or receiver is still online.
The scenario requires that the attacker intercepts messages using stolen TLS certificates or by gaining access to Apple's servers. While the attack takes a high level of technical expertise to be successful, the researchers note that it would be well within the means of state-sponsored actors.
Overall, our determination is that while iMessage’s end-to-end encryption protocol is an improvement over systems that use encryption on network traffic only (e.g., Google Hangouts), messages sent through iMessage may not be secure against sophisticated adversaries.
The team also discovered that Apple doesn't rotate encryption keys at regular intervals, in the way that modern encryption protocols such as OTR and Signal do. This means that the same attack can be used on iMessage historical data, which is often backed up inside iCloud. In theory, law enforcement could issue a court order forcing Apple to provide access to their servers and then use the attack to decrypt the data.
The researchers believe the attack could also be used on other protocols that use the same encryption format, such as Apple's Handoff feature, which transfers data between devices via Bluetooth. OpenPGP encryption (as implemented by GnuPGP) may be vulnerable to similar attacks when used in instant messaging applications, the paper noted.
Apple was notified of the issue as early as November 2015 and patched the iMessage protocol in iOS 9.3 and OS X 10.11.4 as a result. Since that time, the company has been pushing out further mitigations recommended by the researchers through monthly updates to several of its products.
However, the team's long-term recommendation is that Apple should replace the iMessage encryption mechanism with one that eliminates weaknesses in the protocol's core distribution mechanism.
The paper detailing the security issue is called Dancing on the Lip of the Volcano: Chosen Ciphertext Attacks on Apple iMessage, and was published as part of the USENIX Security Symposium, which took place in Austin, Texas. You can read the full paper here.
Top Rated Comments
Jesus ****ing christ on a stick we're less than three comments in and 2/3 of them are dismissing this out of hand because it's not a 100% positive Apple story but a constructive criticism of how they can improve weaknesses in their cryptography.
Green is part of the group which developed Zerocoin ('https://en.wikipedia.org/wiki/Zerocoin'), an anonymous cryptocurrency ('https://en.wikipedia.org/wiki/Cryptocurrency'). His research team has exposed flaws in more than one third of SSL/TLS ('https://en.wikipedia.org/wiki/Transport_Layer_Security') encrypted web sites as well as vulnerabilities in encryption technologies, including RSA BSAFE ('https://en.wikipedia.org/wiki/RSA_BSAFE'), Exxon/Mobil Speedpass ('https://en.wikipedia.org/wiki/Speedpass'), E-ZPass ('https://en.wikipedia.org/wiki/E-ZPass'), and automotive security systems. In 2015, Green was a member of the research team that identified the Logjam ('https://en.wikipedia.org/wiki/Logjam_(computer_security)') vulnerability in the TLS protocol.
Green is a member of the technical advisory board for the Linux Foundation Core Infrastructure Initiative, formed to address critical Internet security concerns in the wake of the Heartbleed ('https://en.wikipedia.org/wiki/Heartbleed') security bug disclosed in April 2014 in the OpenSSL ('https://en.wikipedia.org/wiki/OpenSSL') cryptography library.
He sits on the technical advisory boards for CipherCloud ('https://en.wikipedia.org/wiki/CipherCloud'), Overnest and Mozilla Cybersecurity Delphi. Green co-founded and serves on the Board for Directors of the Open Crypto Audit Project (OCAP), which undertook a security audit ('https://en.wikipedia.org/wiki/Security_audit') of the TrueCrypt ('https://en.wikipedia.org/wiki/TrueCrypt') software.
https://en.wikipedia.org/wiki/Matthew_D._Green