Microsoft is warning Mac users to update to the latest version of MacOS Monterey after it found a vulnerability in Apple’s Transparency, Consent, and Control (TCC) feature.
Exploiting this vulnerability could allow malicious actors to spoof the TCC and plant malware or hijack another app on the computer.
Introduced in 2012 with MacOS Mountain Lion, TCC is designed to help control an app’s access to things such as the camera, microphone, and data. When an app requests access to protected data, the request is compared to existing stored records in a special database. If the records exist, then the app is denied or approved access based on a flag that denotes the level of access.
Otherwise, a prompt is shown to the user to explicitly grant or deny access. Once the user responds, that request is stored in the database and future requests will follow the user’s previous input.
According to Microsoft, the “powerdir” vulnerability, also known as CVE-2021-30970, was actually exploited two times by their security researchers. The first “proof of concept” exploit basically planted a fake TCC database file and changed the user’s home directory.
By doing this, Microsoft was able to change the settings on any application or enable access to the microphone or camera. Microsoft was even cheekily able to give Teams mic and camera access. Microsoft reported these initial findings to Apple in July 2021, though the exploit apparently still worked, despite Apple fixing a similar exploit demonstrated at Black Hat 2021.
The second proof of concept exploit came about because a change in MacOS Monterey’s dsimport tool broke the first exploit. This new exploit allows an attacker to use code injection to change binary called /usr/libexec/configd. This binary is responsible for making system level configuration changes, including access to the TCC database. This allowed Microsoft to silently change the home directory and execute the same kind of attack as the first exploit.
Fortunately, Microsoft again notified Apple of the vulnerability, and it was patched last month. Microsoft is urging macOS users to ensure that their version of MacOS Monterey is updated with the latest patch. The company also took time to promote its own Defender for Endpoint enterprise security solution, which was able to prevent those exploits even before Apple patched them.
There have been previous TCC exploits, including one that utilizes Apple’s built in Time Machine utility, that have since been patched as well. It’s always highly advised to keep all of your devices updated with the latest patches to prevent possible exploits like this. Feel free to read the details of Microsoft’s TCC exploits on their security blog post.