Horizon Alert
Summary of the vulnerability and why it matters
Windows operating systems utilize the "Mark of the Web" (MOTW) feature to identify files downloaded from the internet and apply security warnings or restrictions. A flaw in this feature allows attackers to bypass these protections, potentially enabling the execution of malicious code without the expected security prompts or safeguards. This bypass can weaken defenses like Microsoft Office's Protected View and Windows Defender SmartScreen, increasing the risk of unauthorized actions on affected systems.
- Bypass of downloaded file security markings.
- Malicious file execution without warnings.
- Limited integrity and availability loss.
Attack Path
How an attacker could exploit the issue
This vulnerability allows an attacker to bypass the Windows Mark of the Web security feature. Exploitation can lead to a limited loss of integrity and availability for security features that rely on this tagging, such as Microsoft Office's Protected View. The attack requires an attacker to trick a user into interacting with a malicious file.
- Malicious file shared with user.
- User opens the file.
- Bypassed security controls.
Live Threat
Current exploitation, exposure, and threat context
This vulnerability affects Windows operating systems, potentially allowing attackers to bypass security features designed to protect users from untrusted files. Successful exploitation could lead to a limited loss of data integrity and availability, impacting security measures like Microsoft Office's Protected View. The organization should consider this a moderate risk due to the potential for bypassing security controls.
- Attackers with basic skills.
- Requires user interaction to open a file.
- Moderate business risk.
Priority actions
Operational Fix
Recommended remediation, mitigation, and detection steps
This vulnerability affects Microsoft Windows and could allow attackers to bypass security features by manipulating how downloaded files are identified. Exploitation could lead to a limited loss of integrity and availability of security protections, potentially impacting systems that rely on the Mark of the Web feature. Organizations should take immediate steps to address this risk.
- Identify Windows assets and configurations.
- Reduce exposure to downloaded files.
- Apply vendor updates and verify.
- Monitor for related security events.
