CVE-2024-21351: 
vulnerability analysis and mitigation

Windows SmartScreen Security Feature Bypass Vulnerability (CVE-2024-21351) was discovered and disclosed in February 2024. This vulnerability affects Windows SmartScreen security features and has been confirmed to be exploited in the wild as a zero-day. The vulnerability received a CVSSv3 score of 7.6 and is rated as moderate severity (NVD, Tenable Blog).

The vulnerability allows attackers to bypass SmartScreen security features by convincing targets to open malicious files. When exploited, it enables code injection into SmartScreen, potentially leading to code execution. This vulnerability is particularly significant as it's the fifth Windows SmartScreen vulnerability that has been exploited in the wild as a zero-day since 2022 (Tenable Blog, Help Net Security).

The successful exploitation of this vulnerability could result in SmartScreen security feature bypass, potentially leading to data exposure and system availability issues. The vulnerability affects Windows' Mark-of-the-Web (MotW) functionality, which is crucial for distinguishing files from untrusted locations, allowing attackers to evade this inspection and execute code in the background (Help Net Security).

Microsoft has released patches for this vulnerability as part of the February 2024 Patch Tuesday updates. Organizations are strongly advised to test and implement these patches quickly to protect against potential exploitation (Tenable Blog).