A critical zero-day vulnerability in WinZip, tracked as CVE-2025-33028, allows attackers to bypass Windows' Mark-of-the-Web (MotW) security mechanism. Normally, MotW tags files downloaded from the internet, triggering security warnings upon access. However, WinZip fails to preserve this metadata during extraction, enabling malicious files such as macro-enabled Word documents to execute silently without user prompts.

The exploit is simple, an attacker compresses a harmful file into a ZIP archive and distributes it via phishing emails or compromised sites. When a victim extracts the archive using WinZip, the file appears trusted and can run undetected. This vulnerability carries a high severity impact and could lead to arbitrary code execution, privilege escalation, and data exfiltration. Alarmingly, it appears related to an earlier flaw CVE-2024-8811 indicating ongoing issues in WinZip’s handling of archive files.

Similar MotW bypass vulnerabilities have also been reported in other tools, such as 7-Zip (CVE-2025-0411) and WinRAR (CVE-2025-31334). No patch for WinZip is currently available, prompting security experts to advise against using it for untrusted archives. Users should opt for alternative tools that retain MotW tags, scan extracted files with antivirus software, and disable macro autoloading in Office apps.

In enterprise environments, implementing restrictions on executing newly extracted files and reinforcing layered defenses is recommended. This incident highlights the risks of seemingly routine tasks like file extraction and the importance of vigilant security practices.