A critical vulnerability in WinZip, tracked as CVE-2025-33028, compromises Windows’ Mark-of-the-Web (MotW) security feature. This flaw, present in WinZip versions up to 29.0, allows attackers to bypass crucial security checks and execute malicious code without alerting users. The MotW mechanism flags internet-downloaded files and triggers warnings when users attempt to open potentially dangerous content. However, WinZip fails to propagate this tag when extracting files, leaving victims vulnerable to hidden malware in archives.
Researchers discovered that attackers can exploit this flaw by creating malicious files, such as macro-enabled Office documents, and compressing them into archives.
When victims extract these files using WinZip, the extracted files execute without triggering Windows’ typical warnings, creating a silent attack vector. This vulnerability poses a significant risk because it allows attackers to bypass Windows’ built-in protection, enabling unauthorized code execution and data theft with minimal technical expertise. The flaw’s severity is amplified by its ability to evade security warnings and appear legitimate to the user.
This vulnerability is not isolated to WinZip. Other popular archive utilities, including 7-Zip and WinRAR, have also been affected by similar MotW bypass flaws.
The issue suggests a broader problem in securing archive extraction processes, which attackers are actively exploiting. In response, WinRAR released a patch in version 7.11 to address its own MotW bypass vulnerability. However, as of now, WinZip has not issued a fix, leaving users exposed to potential exploitation.
Until a patch is available, users are urged to exercise caution when opening archive files from untrusted sources. They should use alternative archive utilities that properly handle the MotW tag, scan extracted files with up-to-date antivirus software, and disable automatic macro execution in Office applications. This incident highlights the growing risk of cyberattacks targeting seemingly harmless file operations and emphasizes the need for comprehensive security measures to protect against these evolving threats.
