A high severity vulnerability in 7-Zip is exploiting in the wild. This vulnerability, identified as a Mark-of-the-Web (MoTW) bypass, allows attackers to craft a double archive file that, when extracted, bypasses MoTW protections.

Overview

The vulnerability enables threat actors to create archives containing malicious scripts or executables, which, due to the flaw, will not receive the usual MoTW protection.

This exposes Windows users to potential attacks and has recently been added to the CISA Known Exploited Vulnerabilities Catalog. Furthermore, a Proof of Concept (PoC) for this vulnerability has been publicly released, increasing the risk of exploitation.

7-Zip vulnerability allows attackers to bypass the Mark of the Web (MotW) Windows security feature and was exploited by Russian hackers as a zero-day since September 2024.

Technical Summary

This vulnerability bypasses the Mark-of-the-Web (MoTW) feature, a security measure in Windows operating systems that flags files originating from the internet as potentially untrusted. MoTW is typically applied to files like downloaded documents, images, or executable files, which prompts a warning when opened. However, this vulnerability occurs when 7-Zip fails to properly propagate MoTW protections to files inside double-encapsulated archives.

An attacker can craft an archive containing another archive (a “double archive”), and 7-Zip did not properly propagate MoTW protections to the content to the inner archive.

This flaw allows any malicious content in the inner archive to be executed without triggering any security warnings. Consequently, this exposes Windows users to the risk of remote code execution and other malicious activities.

Remediation:

Update 7zip to v24.09 or the latest version. Installing the latest version will ensure that vulnerability is addressed, protecting systems from potential exploitation.

Generic Recommendations

• Exercise Caution with File Extraction: Always verify the source before extracting files, especially from unfamiliar or untrusted sources.
• Enhance User Awareness: Educate users on identifying phishing attempts and avoiding clicks on suspicious links or attachments.
• Monitor for Anomalies: Continuously monitor systems for signs of exploitation, unusual file extraction behaviors, or unauthorized access attempts.

Conclusion

The MoTW bypass vulnerability in 7-Zip represents a serious security concern for Windows users, as it allows attackers to circumvent protective measures and execute malicious code. Updating to the latest version of 7-Zip is the recommended action to ensure systems are protected against this vulnerability.

References:

• https://nvd.nist.gov/vuln/detail/CVE-2025-0411
• https://www.zerodayinitiative.com/advisories/ZDI-25-045/
• https://www.trendmicro.com/en_us/research/25/a/cve-2025-0411-ukrainian-organizations-targeted.html
• https://cybersecuritynews.com/poc-exploit-released-for-7-zip-vulnerability/
• https://github.com/dhmosfunk/7-Zip-CVE-2025-0411-POC

#CyberSecurity #7Zip #SecurityAdvisory #VulnerabilityManagement #CISO #CXO #PatchManagement #Intrucept