CVE-2025-33028: WinZip Flaw Exposes Users to Silent Code Execution via MotW Bypass, No Patch

A security flaw has been unearthed in WinZip, the popular file compression utility, placing millions of users at risk of silent code execution. Tracked as CVE-2025-33028, this vulnerability enables a Mark-of-the-Web (MotW) bypass, allowing attackers to deliver malicious payloads via crafted archives without triggering the usual Windows security prompts.

The Mark-of-the-Web is a Windows security feature that flags files downloaded from the internet with a special alternate data stream. This flag ensures that when such files are opened—especially those containing macros or executables—Windows issues a warning before they run. It’s a crucial first line of defense against phishing and malware-laden documents.

However, this safeguard breaks down completely in the case of CVE-2025-33028.

“WinZip does not propagate the Mark-of-the-Web protection to the extracted files when opening an archive that has been downloaded from the internet,” according to the vulnerability disclosure.

When users download a malicious archive (e.g., .zip, .7z) and extract it using WinZip version 29.0 (64-bit), the contained files lose their MotW tag. This makes them appear safe to Windows—even if they’re embedded with dangerous macros or scripts.

Here’s how attackers can exploit this vulnerability:

1. Malicious Archive Creation: The attacker crafts a malicious archive file (e.g., .zip or .7z) containing a harmful file, such as a weaponized .docm (macro-enabled Word document).
2. Delivery and MotW Tagging: This archive is then distributed and downloaded from the internet. As a result of the download, the archive is tagged with the Mark-of-the-Web.
3. WinZip Extraction: The user opens the downloaded archive with WinZip and extracts its contents.
4. MotW Removal: Critically, WinZip strips the MotW tag from the extracted malicious file.
5. Malicious Code Execution: The extracted file is now treated as a trusted, local file, allowing the malicious macros or scripts within it to execute without triggering security warnings.

The consequences of this vulnerability can be severe:

1. Code Execution: Attackers can execute arbitrary code on the victim’s system, potentially installing malware or taking control of the machine.
2. Escalation of Privileges: Exploitation could allow attackers to gain elevated privileges within the user’s context, enabling them to perform actions they wouldn’t normally be authorized to do.
3. Information Disclosure: Sensitive data stored on the compromised system could be accessed and stolen by attackers.

As of this writing, no official fix has been released by WinZip Computing. Users are strongly urged to:

• Avoid opening untrusted archives with WinZip.
• Use alternative archive tools that honor MotW (like Windows’ built-in extractor).
• Deploy endpoint protection capable of detecting malicious macro execution.

Related Posts:

• CVE-2025-0411: 7-Zip Security Vulnerability Enables Code Execution – Update Now
• PoC for 7-Zip CVE-2025-0411 Lets Attackers Bypass MotW and Run Malicious Code
• CVE-2025-1240: WinZip Vulnerability Opens Door to Remote Code Execution
• CVE-2024-8811: WinZip Flaw Allows Malicious Code Execution