PANGU 9 INTERNALS presented at blackhatUS 2016

by Tielei Wang, Hao Xu, Xiaobo Chen,

Summary : Pangu 9, the first (and only) untethered jailbreak tool for iOS 9, exploited a sequence of vulnerabilities in the iOS userland to achieve final arbitrary code execution in the kernel and persistent code signing bypass. Although these vulnerabilities were fixed in iOS 9.2, there are no details disclosed. This talk will reveal the internals of Pangu 9. Specifically, this talk will first present a logical error in a system service that is exploitable by any container app through XPC communication to gain arbitrary file read/write as mobile. Next, this talk will explain how Pangu 9 gains arbitrary code execution outside the sandbox through the system debugging feature. This talk will then elaborate a vulnerability in the process of loading the dyld_shared_cache file that enables Pangu 9 to achieve persistent code signing bypass. Finally, this talk will present a vulnerability in the backup-restore process that allows apps signed by a revoked enterprise certificate to execute without the need of the user's explicit approval of the certificate.