CVE-2024-20697 is a high-severity heap-based buffer overflow vulnerability (CWE-122) affecting Microsoft Windows 11 version 22H2 (build 10.0.22621.0). The vulnerability resides in the Windows libarchive component, which is responsible for handling archive files. A heap-based buffer overflow occurs when the software writes more data to a buffer located on the heap than it can hold, potentially overwriting adjacent memory. This flaw can be exploited remotely to achieve remote code execution (RCE), allowing an attacker with limited privileges (local access with low privileges) and requiring user interaction to execute arbitrary code in the context of the affected system. The CVSS 3.1 base score is 7.3, indicating a high severity level, with a vector string of AV:L/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:H, meaning the attack requires local access, low attack complexity, low privileges, and user interaction, but can fully compromise confidentiality, integrity, and availability of the system. No known exploits are currently reported in the wild, and no official patches have been linked yet. The vulnerability was reserved in late November 2023 and published in January 2024. Given the nature of the vulnerability, an attacker could craft malicious archive files that, when opened or processed by the vulnerable libarchive component, trigger the overflow and execute arbitrary code, potentially leading to full system compromise or lateral movement within a network.

For European organizations, this vulnerability poses a significant risk, especially in environments where Windows 11 22H2 is deployed widely. The ability to remotely execute code with high impact on confidentiality, integrity, and availability means that sensitive data could be exfiltrated, systems could be manipulated or destroyed, and operational disruptions could occur. Sectors such as finance, healthcare, government, and critical infrastructure are particularly at risk due to the potential for espionage, data breaches, and service outages. The requirement for local access and user interaction somewhat limits the attack vector, but phishing or social engineering campaigns could be used to trick users into opening malicious archives. The lack of known exploits in the wild currently provides a window for proactive mitigation, but the high severity score indicates that once exploits emerge, rapid exploitation could follow. European organizations with remote or hybrid workforces may face increased exposure if users handle archive files from untrusted sources. Additionally, the vulnerability could be leveraged in targeted attacks against high-value targets or supply chain compromises.

European organizations should prioritize the following mitigations: 1) Implement strict email and file scanning policies to detect and block malicious archive files before they reach end users. 2) Educate users on the risks of opening archive files from untrusted or unexpected sources, emphasizing caution with unsolicited attachments. 3) Employ application whitelisting and sandboxing technologies to isolate archive processing and limit potential damage from exploitation. 4) Monitor systems for unusual behavior indicative of exploitation attempts, including unexpected process launches or memory anomalies related to libarchive usage. 5) Maintain up-to-date backups and incident response plans to recover quickly if compromise occurs. 6) Track Microsoft security advisories closely and apply patches immediately upon release, as no patches are currently linked but are expected. 7) Consider deploying endpoint detection and response (EDR) solutions capable of detecting heap-based buffer overflow exploitation techniques. 8) Restrict local user privileges where possible to reduce the impact of low-privilege code execution. These targeted measures go beyond generic advice by focusing on the specific attack vector and exploitation requirements of this vulnerability.