PoC Released for Dangerous iOS Kernel Exploit

25.8.2017 securityweek iOS
Proof-of-concept (PoC) code has been released for recently patched iOS vulnerabilities that can be chained to take full control of a mobile device. The flaws could also be useful for a jailbreak, according to the researcher who found them.

iOS 10.3.2, which Apple released in mid-May, patches seven AVEVideoEncoder vulnerabilities and one IOSurface flaw discovered by Adam Donenfeld of mobile security firm Zimperium. The security holes, which Apple says can be used by an application to gain kernel privileges, are believed to affect all prior versions of the iOS operating system.

The vulnerabilities are tracked as CVE-2017-6979, CVE-2017-6989, CVE-2017-6994, CVE-2017-6995, CVE-2017-6996, CVE-2017-6997, CVE-2017-6998 and CVE-2017-6999. The bugs were discovered between January 24 and March 20, when they were reported to Apple.

Donenfeld, who disclosed his findings this week at the Hack in the Box security conference in Singapore, said he identified the vulnerabilities while analyzing iOS kernel modules. His analysis led to a little-known module, called AppleAVE, which appeared to lack basic security.

Donenfeld demonstrated how some of the flaws in AppleAVE and IOSurface, which can lead to denial-of-service (DoS), information disclosure and privilege escalation, can be chained to achieve arbitrary read/write and root access. The exploit is said to bypass all iOS security mitigations.

“These vulnerabilities would allow elevation of privileges which ultimately can be used by the attacker to take complete control over affected devices,” the researcher said in a blog post.

The expert has released a PoC exploit, which he calls the zIVA (Zimperium’s iOS Video Audio) exploit, to demonstrate his findings. The exploit can be used to take complete control of the kernel, which means it could also be useful for a jailbreak.

Technical details have been made public for only one of the vulnerabilities, but Zimperium will release all the advisories it sent to Apple. The tech giant had asked the security firm to delay the release of the exploit, likely in an effort to give users time to update their devices.