Day: May 2, 2013

iOS Counter Forensics: Encrypting SMS and Other Crypto-Hardening

As I explained in a recent blog post, your iOS device isn’t as encrypted as you think. In fact, nearly everything except for your email database and keychain can (and often is) recovered by Apple under subpoena (your device is either sent to or flown to Cupertino, and a copy of its hard drive contents are provided to law enforcement). Depending on your device model, a number of existing forensic imaging tools can also be used to scrape data off of your device, some of which are pirated in the wild. Lastly, a number of jailbreak and hacking tools, and private exploits can get access to your device even if it is protected with a passcode or a PIN. The only thing protecting your data on the device is the tiny sliver of encryption that is applied to your email database and keychain. This encryption (unlike the encryption used on the rest of the file system) makes use of your PIN or passphrase to encrypt the data in such a way that it is not accessible until you first enter it upon a reboot. Because nearly every working forensics or hacking tool for iOS 6 requires a reboot in order to hijack the phone, your email database file and keychain are “reasonably” secure using this better form of encryption.

While I’ve made remarks in the past that Apple should incorporate a complex boot passphrase into their iOS full disk encryption, like they do with File Vault, it’s fallen on deaf ears, and we will just have to wait for Apple to add real security into their products. It’s also beyond me why Apple decided that your email was the only information a consumer should find “valuable” enough to encrypt. Well, since Apple doesn’t have your security in mind, I do… and I’ve put together something you can do to protect the remaining files on your device. This technique will let you turn on the same type of encryption used on your email index for other files on the device. The bad news is that you have to jailbreak your phone to do it, which reduces the overall security of the device. The good news is that the trade-off might be worth it. When you jailbreak, not only can unsigned code run on the device, but App Store applications running inside the sandbox will have access to much more personal data they previously didn’t have access to, due to certain sandbox patches that are required in order to make the jailbreak work. This makes me feel uneasy, given the amount of spyware that’s already been found in the App Store… so you’ll need to be careful what you install if you’re going to jailbreak. The upside is that , by protecting other files on your device with Data-Protection encryption, forensic recovery will be highly unlikely without knowledge of (or brute forcing) your passphrase. Files protected this way are married to your passphrase, and so even with physical possession of your device, it’s unlikely they’d be recoverable.

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