CVE-2024-40827 is a vulnerability identified in Apple macOS that allows a local application to overwrite arbitrary files on the system due to insufficient validation checks. This flaw affects multiple macOS versions prior to Sonoma 14.6, Monterey 12.7.6, and Ventura 13.6.8, which include the security fixes. The vulnerability does not require user interaction but does require the app to have low-level privileges on the system, which means an attacker must already have some form of local access, such as through a compromised user account or malicious app installation. The core issue is that the operating system fails to properly verify the legitimacy of file overwrite operations initiated by an app, enabling it to modify files it should not be permitted to alter. This can lead to integrity violations, such as overwriting system or user files, potentially allowing persistence of malicious code or disruption of normal system operations. The CVSS v3.1 score is 5.5 (medium), reflecting the local attack vector, low complexity, low privileges required, no user interaction, and impact limited to integrity without affecting confidentiality or availability. No public exploits or active exploitation have been reported so far. The vulnerability was addressed by Apple through improved checks in the specified macOS updates. Organizations running affected macOS versions should apply these patches promptly to mitigate the risk.

For European organizations, this vulnerability poses a risk primarily to the integrity of systems running vulnerable macOS versions. An attacker with local access could overwrite critical files, potentially leading to unauthorized persistence mechanisms, tampering with application or system files, or corrupting data. This could disrupt business operations, compromise system trustworthiness, or facilitate further attacks. Sectors relying heavily on macOS devices, such as creative industries, software development firms, and certain government agencies, may be particularly impacted. Although the vulnerability does not affect confidentiality or availability directly, the ability to modify arbitrary files can be leveraged as a stepping stone for more severe attacks. The lack of required user interaction lowers the barrier for exploitation once local access is obtained, increasing the threat in environments where endpoint security controls are weak or where users may inadvertently install untrusted applications. The absence of known exploits in the wild reduces immediate risk but does not eliminate the potential for future exploitation. Organizations must consider the risk in the context of their macOS usage and local access controls.

1. Immediately apply the security updates released by Apple: macOS Sonoma 14.6, Monterey 12.7.6, and Ventura 13.6.8 or later. 2. Enforce strict application installation policies to prevent unauthorized or untrusted apps from running on macOS systems. 3. Implement endpoint protection solutions that monitor and restrict file system modifications by applications, especially those running with low privileges. 4. Use macOS built-in security features such as System Integrity Protection (SIP) and Full Disk Encryption to limit the impact of file overwrite attempts. 5. Regularly audit and monitor local user accounts and their privileges to reduce the risk of local compromise. 6. Educate users about the risks of installing untrusted software and encourage adherence to organizational security policies. 7. Employ application whitelisting and sandboxing where feasible to contain app capabilities. 8. Maintain up-to-date backups to recover from any potential file corruption or tampering incidents.