The new generation of jailbreaks has arrived. Available for iOS 11 and iOS 12 (up to and including iOS 12.1.2), rootless jailbreaks offer significantly more forensically sound extraction compared to traditional jailbreaks. Learn how rootless jailbreaks are different to classic jailbreaks, why they are better for forensic extractions and what traces they leave behind.
Privilege Escalation
If you are follow our blog, you might have already seen articles on iOS jailbreaking. In case you didn’t, here are a few recent ones to get you started:
In addition, we published an article on technical and legal implications of iOS file system acquisition that’s totally worth reading.
Starting with the iPhone 5s, Apple’s first iOS device featuring a 64-bit SoC and Secure Enclave to protect device data, the term “physical acquisition” has changed its meaning. In earlier (32-bit) devices, physical acquisition used to mean creating a bit-precise image of the user’s encrypted data partition. By extracting the encryption key, the tool performing physical acquisition was able to decrypt the content of the data partition.
Secure Enclave locked us out. For 64-bit iOS devices, physical acquisition means file system imaging, a higher-level process compared to acquiring the data partition. In addition, iOS keychain can be obtained and extracted during the acquisition process.
Low-level access to the file system requires elevated privileges. Depending on which tool or service you use, privilege escalation can be performed by directly exploiting a vulnerability in iOS to bypass system’s security measures. This is what tools such as GrayKey and services such as Cellebrite do. If you go this route, you have no control over which exploit is used. You won’t know exactly which data is being altered on the device during the extraction, and what kind of traces are left behind post extraction.
In iOS Forensic Toolkit, we rely on public jailbreaks to circumvent iOS security measures. The use of public jailbreaks as opposed to closed-source exploits has its benefits and drawbacks. The obvious benefit is the lower cost of the entire solution and the fact you can choose the jailbreak to use. On the other hand, classic jailbreaks were leaving far too many traces, making them a bit overkill for the purpose of file system imaging. A classic jailbreak has to disable signature checks to allow running unsigned code. A classic jailbreak would include Cydia, a third-party app store that requires additional layers of development to work on jailbroken devices. In other words, classic jailbreaks such as Electra, Meridian or unc0ver carry too many extras that aren’t needed or wanted in the forensic world. Read the rest of this entry »
