Security Experts:

Exploit for OS X Zero-Day Published by Researcher

A researcher has published a proof-of-concept (PoC) exploit for a local privilege escalation vulnerability affecting OS X Yosemite, including the latest 10.10.5 version.

The exploit was published on GitHUb over the weekend by Italian researcher Luca Todesco. The expert has refused to say why he decided to drop the zero-day without giving Apple a chance to fix the issue. “All I can say is that I had my reasons,” he told SecurityWeek.

Todesco says the vulnerability was patched by Apple in the beta version of OS X 10.11, dubbed El Capitan. This could indicate that Apple has been aware of the security hole, but the researcher noted that the company “could have simply refactored some code.”

Apple has not immediately responded to SecurityWeek’s request for comment.

The local privilege escalation attack, dubbed by the researcher “tpwn,” involves two security bugs. An attacker can leverage the technique to obtain root privileges, but only if he can execute a specially crafted file, the expert said.

NULLGuard, a tool designed by Todesco, can be used to mitigate tpwn and other attacks involving NULL pointer dereference bugs.

OS X 10.10.5 was released by Apple last week. The latest stable version of the Mac operating system attempts to patch a total of 135 vulnerabilities, including a local privilege escalation vulnerability (CVE-2015-3760) disclosed publicly in July by German researcher Stefan Esser.

This particular flaw was reported privately to Apple months ago by a researcher known as “beist.” However, the company only released a patch after experts warned that the weakness had been exploited in the wild to install adware.

Esser announced on Monday that he has updated his SUIDGuard tool to help users protect themselves against the tpwn exploit. Todesco has also recommended SUIDGuard for mitigating attacks.

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Eduard Kovacs (@EduardKovacs) is a contributing editor at SecurityWeek. He worked as a high school IT teacher for two years before starting a career in journalism as Softpedia’s security news reporter. Eduard holds a bachelor’s degree in industrial informatics and a master’s degree in computer techniques applied in electrical engineering.