CVE-2024-27876 is a race condition vulnerability identified in Apple’s macOS and related operating systems, including iOS, iPadOS, and visionOS. The flaw stems from improper locking during the unpacking process of archive files, which allows an attacker to exploit a time-of-check to time-of-use (TOCTOU) race condition. By crafting a malicious archive and tricking a user into unpacking it, an attacker can write arbitrary files to the system. This could lead to overwriting critical files or planting malicious payloads, potentially resulting in unauthorized code execution or data corruption. The vulnerability affects multiple Apple OS versions, notably macOS Ventura 13.7, Sonoma 14.7, Sequoia 15, iOS 17.7 and 18, iPadOS 17.7 and 18, and visionOS 2. The issue was addressed by Apple through improved locking mechanisms in these versions. The CVSS v3.1 score is 8.1, reflecting high severity due to network attack vector (AV:N), low attack complexity (AC:L), no privileges required (PR:N), but requiring user interaction (UI:R). The impact on confidentiality and integrity is high, while availability is not affected. Although no exploits are currently known in the wild, the vulnerability presents a significant risk given the widespread use of Apple devices and the potential for arbitrary file writes. The CWE classification is CWE-362, indicating a race condition vulnerability. Organizations should be aware of the risk posed by malicious archives and ensure timely patching and monitoring.

For European organizations, this vulnerability poses a significant risk especially in environments where Apple devices are prevalent. The ability to write arbitrary files without privileges can lead to unauthorized code execution, data tampering, or persistence mechanisms for attackers. Confidentiality and integrity of sensitive data can be compromised, impacting sectors such as finance, healthcare, government, and critical infrastructure. The requirement for user interaction (unpacking an archive) means phishing or social engineering could be used to trigger exploitation. The high CVSS score indicates a serious threat that could facilitate lateral movement or privilege escalation if combined with other vulnerabilities. Disruption to business operations is possible if critical files are overwritten or system integrity is compromised. Given the widespread use of Apple devices in European enterprises and public sector organizations, the vulnerability could be leveraged in targeted attacks or broader campaigns if exploited in the wild.

1. Apply the latest Apple OS updates immediately, specifically macOS Ventura 13.7, Sonoma 14.7, Sequoia 15, iOS 17.7 and 18, iPadOS 17.7 and 18, and visionOS 2, which contain the fix for this vulnerability. 2. Restrict or monitor the unpacking of archive files from untrusted or unknown sources to reduce the risk of triggering the vulnerability. 3. Implement endpoint detection and response (EDR) solutions capable of monitoring suspicious file system activity during archive extraction. 4. Educate users about the risks of opening archives from untrusted emails or websites to reduce the likelihood of social engineering exploitation. 5. Employ application whitelisting and strict file integrity monitoring to detect unauthorized file writes or modifications. 6. Use network security controls to block or flag suspicious archive files entering the network. 7. Regularly audit and review system logs for unusual file creation or modification patterns that could indicate exploitation attempts.