Zero-day vulnerability in macOS

Security features bypass
CVE-2021-30657

The Jamf Protect detections team observed this exploit being used in the wild by a variant of the Shlayer adware dropper, as early as January 9th, 2021.

Known malware:

Shlayer

Vulnerability details

Advisory: SB2021042704 - Multiple vulnerabilities in macOS

Vulnerable component: macOS

CVE-ID: CVE-2021-30657

CVSSv3 score: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H/E:H/RL:O/RC:C

CWE-ID: CWE-254 - Security Features

Description:

The vulnerability allows a remote attacker to bypass implemented security restrictions.

The vulnerability exists due to a logic issue within the Gatekeeper checks. A remote attacker can craft a specially crafted payload that is not checked by Gatekeeper and bypasses File Quarantine and Application Notarization protections as well. As a result, a malicious binary can be executed on the system.

Note, the vulnerability is being actively exploited in the wild.

External links:

https://support.apple.com/en-us/HT212325

About zero-day vulnerabilities

Zero-day vulnerability is an undisclosed vulnerability in software that hackers can exploit to compromise computer programs, gain unauthorized access to sensitive data, penetrate networks, etc. We consider vulnerability a zero-day when there is no solution provided from software vendor and the vulnerability is being actively exploited by malicious actors.

Zero-day candidate is a potential zero-day vulnerability in software which might have been used in targeted attacks, however there is no evidence to support this suggestion.