CVE-2024-38213 is a medium-severity vulnerability affecting Microsoft Windows 10 Version 1809 (build 10.0.17763.0). The vulnerability is categorized under CWE-693, which relates to Protection Mechanism Failure. Specifically, this issue involves a bypass of the Windows Mark of the Web (MOTW) security feature. MOTW is designed to mark files downloaded from the internet with a security zone identifier, which Windows uses to enforce security policies such as warning users before opening potentially unsafe content or restricting script execution. A bypass of this mechanism means that malicious files could evade these security checks, potentially allowing harmful content to execute without the usual warnings or restrictions. The CVSS 3.1 base score is 6.5, indicating a medium severity level. The vector string (CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N/E:F/RL:O/RC:C) shows that the vulnerability can be exploited remotely over the network without privileges and requires user interaction (UI:R). The impact is high on integrity (I:H) but does not affect confidentiality or availability. There are no known exploits in the wild at the time of publication, and no patches have been linked yet. The vulnerability was reserved in June 2024 and published in August 2024. This flaw could be leveraged by attackers to deliver malicious payloads that bypass Windows security warnings, increasing the risk of malware infections or unauthorized code execution on affected systems.

For European organizations, this vulnerability poses a significant risk primarily to those still operating legacy systems running Windows 10 Version 1809, which is an older release. The bypass of the Mark of the Web security feature could allow attackers to distribute malicious files that appear safe, increasing the likelihood of successful phishing or social engineering attacks leading to malware infections or integrity compromises. This could affect sectors with high reliance on legacy Windows environments, such as manufacturing, government agencies, and critical infrastructure operators. The integrity impact means that attackers could alter or execute unauthorized code, potentially leading to data manipulation or further compromise within networks. Although confidentiality and availability are not directly impacted, the integrity breach could facilitate lateral movement or persistence mechanisms for attackers. The requirement for user interaction means that phishing or social engineering remains a key attack vector. Given the widespread use of Windows in Europe, organizations that have not updated or migrated from Windows 10 Version 1809 are at risk, especially if they lack robust endpoint protection or user awareness training.

European organizations should prioritize upgrading or migrating systems from Windows 10 Version 1809 to supported, patched versions of Windows 10 or Windows 11 to eliminate exposure to this vulnerability. Until patches are available, organizations should implement strict email and web filtering to block or quarantine files that could exploit the MOTW bypass. Endpoint detection and response (EDR) solutions should be tuned to detect suspicious file execution or behavior indicative of bypass attempts. User training should emphasize caution when opening files from untrusted sources, especially those received via email or downloaded from the internet. Network segmentation can limit the spread of malware if an infection occurs. Additionally, organizations should monitor security advisories from Microsoft for patches or workarounds and apply them promptly once released. Employing application whitelisting and restricting script execution policies can further reduce the risk of exploitation. Finally, maintaining up-to-date backups is critical to recover from potential integrity compromises.