Apple iOS Exploit Takes Complete Control of Kernel

Multiple vulnerabilities in the AppleAVEDriver when linked together create an opportunity to launch an iOS exploit that can take full control of the iOS kernel, security researcher Adam Donenfeld of Zimperium's zLabs revealed today.

Donenfeld, who today demonstrated the exploit at the Hack In the Box conference in Singapore, says all iOS devices running versions 10.3.1 released in April as well as earlier versions are currently vulnerable to the attack. 

Apple patched eight vulnerabilities Donenfeld previously discovered – seven in AppleAVEDriver.kext and one in the iOSurface kernel extension – in its iOS version 10.3.2 in May.

It all began in January when Donefeld was researching the favored path attackers take in hitting Apple's iOS, which entails focusing on the direct containerized app-to-kernel vulnerabilities.

"The attack surface in between [the containerized app and kernel] is often underlooked and has more vulnerabilities, which are, usually, much, much easier to exploit. So, in most cases, even though an attacker has to go through more lines of code, finding and exploiting those bugs is usually an easier job," Donefeld says.

In his app-to-kernel vulnerabilities search, Donefeld did find a bug on Jan. 24, which in turn raised questions in his mind about other iOS attack surfaces. That curiosity led him to dive deeper into Apple's closed-source kernel modules, where he found one he was not familiar with called Apple AVEDriver. That module lacked basic security fundamentals and contained seven vulnerabilities that would allow attackers to elevate privileges by overtaking the kernel and gaining arbitrary read-write and root control.

Building an iOS Kernel Exploit

Donefeld created the fully chained iOS kernel exploit - which he dubbed ZIVA - by linking together the seven vulnerabilities he found in the AppleAVEDriver module, he says.

Some of these AppleAVE vulnerabilities could allow information disclosures, denial of service (DoS), and elevation of privilege (EoP), Donefeld says.

"The issues are severe and could allow the attacker to take complete control of any iOS device on the market prior to version 10.3.2., as well as access information including GPS data, photos, and contact information, or conduct denial-of-service (DoS) attacks," Donefeld says.

He notes that because Apple issued a patch for the flaws with version 10.3.2, iOS users who updated their device to the latest iOS version should be protected. Others, he adds, should invest in a third-party security solution.

"This provides a complete control over the kernel," he says of the exploit.

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