NEW SECURITY BREACH: APPLE SECURE ENCLAVE FOR iOS

A hacker who goes by the alias "xerub" has managed to successfully crack Apple's Secure Enclave firmware decryption key for their iOS devices. The Secure Enclave Processor (SEP) is used by iOS devices to store and manage the encryption keys and authentication process for the device. This includes fingerprint data for Touch ID. Fingerprint Touch ID is the authorisation for sensitive data and allows payment transactions to proceed, including Apple Pay and purchases from the iTunes Store.

Ultimately this type of attack could lead to an authentication bypass attack – making Touch ID redundant - for the device owner. Outcomes include payment authorisations being forged and potential financial loss for the device owner. On top of this, if an attacker is able to inject a backdoor into the Secure Enclave then it would bypass all traditional detection techniques to identify compromised devices, which would allow the attacker to retain control for an extended period of time.

How it Works

The Secure Enclave runs its own version of operating system called SEPOS, which it also ensures is verified and signed by Apple.

The significance of the decryption key being made available is that attackers are now able to decrypt the Secure Enclave firmware to gain access to its previously inaccessible operating system files. This allows new attack vectors and vulnerabilities to be researched to identify ways that the Secure Enclave may become breached.

Example Breach

If an attacker identified a vulnerability within one of the SEPOS operating system executables, then there is a possibility that an exploit could be developed to force the application processor to send malicious data through to the Secure Enclave to trigger the vulnerability in the target executable. This would provide the attacker with the ability to execute arbitrary code within the Secure Enclave. 

A Black Hat presentation in 2016, "Demystifying The Secure Enclave Processor" demonstrated that the SEP lacks anti-exploitation protections including ASLR (Address Space Layout Randomisation) and protections that do exist are oddly easy to bypass, such as static Stack Cookies. This means that once a vulnerability within the Secure Enclave is identified, then the exploit should be relatively straight forward and can be quite small, which can increase the likelihood of the exploit being successful.

This type of attack could lead to authentication bypass attacks for the victim device and payment authorisations being forged to lead to financial losses of the device owner.

Examples of an authentication bypass would be to allow any fingerprint to login to the device via Touch ID, or disable the time delay for passcode attempts that would allow brute force attacks to guess the victim's passcode to login to the device. 

iPhones could become even more valuable

Once this is achieved, you can expect the value of a stolen iPhone to increase dramatically since attackers would be able to bypass your passcode and login to your financial apps, email accounts and social media using any fingerprint. The reality of this type of attack isn't likely to arise in the short term; however, you can guarantee that attackers will be researching these new attack vectors for iOS devices.

Apple's iOS security guide provides some rough bounties for successful attacks:

·        Secure boot firmware components $200,000

·        Extraction of confidential material protected by the Secure Enclave $100,000

·        Execution of arbitrary code with kernel privileges $50,000

·        Unauthorized access to iCloud account data on Apple servers $50,000

·        Access from a sandboxed process to user data outside of that sandbox $25,000.