macOS Big Sur 11.4 Addresses Vulnerability That Could Let Attackers Take Secret Screenshots

macOS Big Sur 11.4, which was released this morning, addresses a zero-day vulnerability that could allow attackers to piggyback off of apps like Zoom, taking secret screenshots and surrepetiously recording the screen.

jamf malware secret screenshots
Jamf, a mobile device management company, today highlighted a security issue that allowed Privacy preferences to be bypassed, providing an attacker with Full Disk Access, Screen Recording, and other permissions without a user's consent.

The bypass was actively exploited in the wild, and was discovered by Jamf when analyzing XCSSET malware. The XCSSET malware has been out in the wild since 2020, but Jamf noticed an uptick in recent activity and discovered a new variant.

Once installed on a victim's system, the malware was used specifically for taking screenshots of the user's desktop with no additional permissions required. Jamf said that it could be used to bypass other permissions as well, as long as the donor application the malware piggybacked off of had that permission enabled.

Jamf has a full rundown on how the exploit worked, and the company says that Apple addressed the vulnerability in macOS Big Sur 11.4, Apple confirmed to TechCrunch that a fix has indeed been enabled in macOS 11.4, so Mac users should update their software as soon as possible.

Related Forum: macOS Big Sur

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Top Rated Comments

Kung gu Avatar
41 months ago
11.4 also fixes excessive ssd writes.

PSA: The SSD disk write issues have been fixed in 11.4 which came out today. The person who found the issue in first place says it was a result of a kernel bug and he also says 11.4 addresses the issue.
Update to 11.4 if your on M1 macs.
Users on this thread also report lower disk writes on 11.4.


[MEDIA=twitter]1396374313591140357[/MEDIA]
Score: 17 Votes (Like | Disagree)
Apple_Robert Avatar
41 months ago

OK just read the report by JAMF. So it piggybacks on fake Xcode projects, then requires the user to grant access through the Terminal and also through System Preferences. I'm glad this was found and dealt with, but it seems like it's a pretty weak exploit since nearly all of these behaviors should alert a user with more than 2 brain cells to stop the process
Unfortunately, a lot of people click accept without really thinking about what they are giving system access to and for what reason.
Score: 11 Votes (Like | Disagree)
deevey Avatar
41 months ago

Unfortunately, a lot of people click accept without really thinking about what they are giving system access to and for what reason.
And that folks, is why iOS should remain locked down tight :)
Score: 10 Votes (Like | Disagree)
Rigby Avatar
41 months ago

I assume this will be backported?
According to the post by JAMF it only affects MacOS 11. The security updates for Mojave ('https://support.apple.com/en-us/HT212531') and Catalina ('https://support.apple.com/en-us/HT212530') that also came out today do not list it.
Score: 8 Votes (Like | Disagree)
Guyferd Avatar
41 months ago

So how was it installed? The usual pirated software? Tricking users into downloading it as a fake utility or game?
OK just read the report by JAMF. So it piggybacks on fake Xcode projects, then requires the user to grant access through the Terminal and also through System Preferences. I'm glad this was found and dealt with, but it seems like it's a pretty weak exploit since nearly all of these behaviors should alert a user with more than 2 brain cells to stop the process
Score: 8 Votes (Like | Disagree)
TheYayAreaLiving ?️ Avatar
41 months ago
Thank you for the heads up. Hide your identity and yourself people!!!



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Score: 7 Votes (Like | Disagree)