7-Zip Mark-of-the-Web Bypass Vulnerability
CVE-2025-0411
CVE-2025-0411 is a critical vulnerability identified in the 7-Zip file archiver, which allows remote attackers to bypass the Mark-of-the-Web (MotW) protection mechanism. This flaw, discovered by researchers from the Trend Micro Zero Day Initiative, has been assigned a CVSS score of 7.0, indicating its high severity. The vulnerability specifically arises from improper handling of archived files, where extracted files do not inherit the MotW designation, potentially allowing for arbitrary code execution in the context of the current user. (Jan 25, 2025)
What is Mark-of-the-Web?
The Mark-of-the-Web is a Windows security feature that flags files downloaded from the internet by adding metadata to indicate their origin. This mechanism helps prevent malicious files from executing automatically by triggering warnings or restrictions when users attempt to access these files. For example, Microsoft Office applications may block macros in documents marked with MotW, ensuring that users are alerted to potential risks.
Exploitation Scenarios
Scenario 1: Phishing Attack via Malicious Archive
- Crafting the Archive: An attacker creates a malicious archive that is designed to bypass MotW by stripping this metadata during extraction.
- Distribution: The archive is distributed through phishing emails or hosted on compromised websites.
- User Interaction: The victim receives the email and downloads the archive, which appears benign due to the absence of MotW warnings.
- Extraction and Execution: Upon extracting the contents using a vulnerable version of 7-Zip (prior to version 24.09), the user unwittingly executes a malicious executable contained within the archive, leading to potential system compromise.
Scenario 2: Nested Compressed Files
- Double Compression: An attacker creates a double-compressed archive containing an executable file designed to execute malicious code.
- Delivery Method: This file is uploaded to a file-sharing service and shared via social engineering tactics.
- Execution without Warnings: When extracted using an affected version of 7-Zip, the executable runs without triggering any Windows security warnings due to the absence of MotW propagation.
Mitigation Strategies
To protect against CVE-2025-0411, users and organizations should take immediate action:
- Update Software: Upgrade to 7-Zip version 24.09 or later, which includes patches for this vulnerability. Users should manually check for updates as 7-Zip lacks an automatic update feature.
- Exercise Caution: Avoid opening files from unknown or suspicious sources, particularly compressed archives that may contain harmful executables.
- Leverage Security Tools: Ensure that endpoint protection solutions are configured to detect and block malicious file activity, providing an additional layer of defense against potential exploits.
Conclusion
CVE-2025-0411 represents a significant risk due to its ability to undermine essential Windows security features designed to protect users from potentially harmful files. Given its exploitation scenarios and high CVSS score, it is crucial for users of 7-Zip to update their software immediately and remain vigilant against phishing attempts and other tactics employed by attackers.