An Apple malware-flagging tool is “trivially” easy to bypass

Close-up photograph of a Macintosh laptop keyboard.

One of your Mac’s built-in malware detection tools may not be working quite as well as you think. At the Defcon hacker conference in Las Vegas, longtime Mac security researcher Patrick Wardle presented findings on Saturday about vulnerabilities in Apple’s macOS Background Task Management mechanism, which could be exploited to bypass and, therefore, defeat the company’s recently added monitoring tool.

There’s no foolproof method for catching malware on computers with perfect accuracy because, at their core, malicious programs are just software, like your web browser or chat app. It can be difficult to tell the legitimate programs from the transgressors. So operating system makers like Microsoft and Apple, as well as third-party security companies, are always working to develop new detection mechanisms and tools that can spot potentially malicious software behavior in new ways.

Apple’s Background Task Management tool focuses on watching for software “persistence.” Malware can be designed to be ephemeral and operate only briefly on a device or until the computer restarts. But it can also be built to establish itself more deeply and “persist” on a target even when the computer is shut down and rebooted. Lots of legitimate software needs persistence so all of your apps and data and preferences will show up as you left them every time you turn on your device. But if software establishes persistence unexpectedly or out of the blue, it could be a sign of something malicious.

With this in mind, Apple added Background Task Manager in macOS Ventura, which launched in October 2022, to send notifications both directly to users and to any third-party security tools running on a system if a “persistence event” occurs. This way, if you know you just downloaded and installed a new application, you can disregard the message. But if you didn’t, you can investigate the possibility that you’ve been compromised.

“There should be a tool [that notifies you] when something persistently installs itself, it’s a good thing for Apple to have added, but the implementation was done so poorly that any malware that’s somewhat sophisticated can…