CVE-2023-42859 is a vulnerability identified in Apple macOS that permits an application to modify protected parts of the file system without requiring privileges or user interaction. The root cause is insufficient access control enforcement (CWE-284) allowing unauthorized write access to critical system areas. This vulnerability affects multiple macOS versions prior to the patched releases: macOS Sonoma 14.1, Monterey 12.7.1, and Ventura 13.6.1, where Apple implemented improved checks to prevent unauthorized modifications. The vulnerability has a CVSS 3.1 base score of 7.7, indicating high severity. The attack vector is local (AV:L), meaning the attacker must have local access but does not require privileges (PR:N) or user interaction (UI:N). Successful exploitation can lead to high confidentiality and integrity impacts by allowing an attacker to alter system files, potentially enabling persistence, privilege escalation, or bypassing security controls. No known exploits in the wild have been reported yet, but the vulnerability's characteristics make it a significant risk if exploited. The flaw highlights the importance of strict access control enforcement in operating system design to protect critical system components from unauthorized modification by unprivileged applications.

For European organizations, this vulnerability poses a significant risk especially to those with macOS endpoints in their environment. Unauthorized modification of protected file system areas can lead to compromise of system integrity, enabling attackers to implant persistent malware, alter security configurations, or exfiltrate sensitive data. Sectors such as finance, government, healthcare, and critical infrastructure that rely on macOS devices for sensitive operations could face increased risk of targeted attacks or insider threats exploiting this vulnerability. The local attack vector means that attackers need some form of local access, which could be achieved through social engineering, physical access, or leveraging other vulnerabilities to gain initial foothold. The lack of required user interaction lowers the barrier for exploitation once local access is obtained. This could facilitate lateral movement within networks or persistence on compromised devices. The confidentiality impact is high as protected files may contain sensitive system or user data, and integrity impact is high due to potential unauthorized changes to system files. Availability impact is not significant in this case. Overall, the vulnerability could undermine trust in macOS security posture within European organizations if not promptly addressed.

1. Immediate deployment of Apple’s security updates: macOS Sonoma 14.1, Monterey 12.7.1, and Ventura 13.6.1 or later versions that include the fix for CVE-2023-42859. 2. Restrict installation of applications to trusted sources such as the Apple App Store or enterprise-approved software repositories to reduce risk of malicious apps gaining local access. 3. Implement endpoint protection solutions that monitor and alert on unauthorized file system modifications, especially in protected system directories. 4. Enforce strict access controls and user privilege management to limit the number of users and processes with local access to macOS devices. 5. Conduct regular audits of installed applications and system file integrity to detect anomalies indicative of exploitation attempts. 6. Educate users on the risks of installing untrusted software and the importance of physical security to prevent unauthorized local access. 7. Use macOS security features such as System Integrity Protection (SIP) and Full Disk Encryption (FileVault) to add layers of defense. 8. For organizations with macOS device management, enforce policies that prevent execution of unsigned or unapproved binaries. These steps collectively reduce the attack surface and improve detection and response capabilities against exploitation of this vulnerability.