iOS Security - Scratching the surface!

Apple Inc. recently published details about iOS security. Its interesting to note that the first iPhone was released in July 2007. iPhone hackers claimed to have pwned iOS within a few days of of the official release.

Here's a high level architectural diagram of iOS representing the different layers of iOS from the pdf.

Source: Apple

What caught my interest was the fact that the entire file system is encrypted. Yes, FDE (Full Disk Encryption) as it called is implemented in iOS. FDE can be complex, performance hungry and a pain to configure at times. Configuration wise, Apple took away the pain by turning it ON by default on your iPhone. Performance wise, the engine to handle encryption, Crypto Engine in the hardware on the iOS thereby reducing the operational overhead. Here's an excerpt describing the implementation: Every iOS device has a dedicated AES 256 crypto engine built into the DMA path between the flash storage and main system memory, making file encryption highly efficient. Along with the AES engine, SHA-1 is implemented in hardware, further reducing cryptographic operation overhead. Security wise, the root certificate for encryption is fused into the processor during manufacture. This would mean if you were to replace the memory chips from one device to another, the files would be inaccessible.

The other point of interest to me was App Code signing. Here's an excerpt that aptly describes this feature: To ensure that all apps come from a known and approved source and have not been tampered with, iOS requires that all executable code be signed using an Apple-issued certificate. Apps provided with the device, like Mail and Safari, are signed by Apple. Third-party apps must also be validated and signed using an Apple-issued certificate. Mandatory code signing extends the concept of chain of trust from the OS to apps, and prevents third-party apps from loading unsigned code resources or using self- modifying code.

Till date, there have been no known instances of malware on the iOS. An exception to this was Ikee, an iPhone worm which stole financially sensitive information from infected iPhones. But, it only ever spread on a iOS which was jailbroken.