CVE-2025-33028: WinZip Mark-of-the-Web Bypass RCE Flaw

CVE-2025-33028 Overview

CVE-2025-33028 is a Mark-of-the-Web (MotW) bypass vulnerability affecting WinZip through version 29.0. This vulnerability represents an incomplete fix for the previously disclosed CVE-2024-8811, allowing attackers to bypass the Windows Mark-of-the-Web protection mechanism. When users extract files from a crafted archive that bears the Mark-of-the-Web, WinZip fails to propagate this security marker to the extracted files, potentially enabling arbitrary code execution in the context of the current user.

Critical Impact

Attackers can leverage this vulnerability to execute arbitrary code by distributing malicious archives that bypass Windows security warnings designed to protect users from untrusted downloaded content.

Affected Products

• WinZip versions through 29.0
• Windows systems relying on Mark-of-the-Web protection
• Systems where users extract archives downloaded from untrusted sources

Discovery Timeline

• 2025-04-15 - CVE-2025-33028 published to NVD
• 2025-10-24 - Last updated in NVD database

Technical Details for CVE-2025-33028

Vulnerability Analysis

This vulnerability stems from WinZip's incomplete handling of the Mark-of-the-Web security attribute during archive extraction. The Mark-of-the-Web is a Windows security feature that tags files downloaded from the internet with a Zone.Identifier alternate data stream, containing metadata such as HostUrl that indicates the file's origin. When Windows applications encounter files with this marker, they can display security warnings or apply restricted execution policies.

The specific flaw exists within WinZip's handling of archived files. When extracting files from archives that carry the Mark-of-the-Web attribute, WinZip does not propagate this critical security marker to the extracted files. This means that executable content extracted from a downloaded archive will not trigger the expected Windows security warnings, potentially leading users to execute malicious content without appropriate caution.

It is important to note that this CVE is currently disputed. Some parties argue that Mark-of-the-Web propagation can actually increase risk through security-warning habituation (users becoming desensitized to frequent warnings), and that the intended control sphere for file-origin metadata may be narrower than for reading file content. Additionally, the original disclosure documentation on GitHub has reportedly been deleted.

Root Cause

The root cause is classified under CWE-830 (Inclusion of Web Functionality from an Untrusted Source). WinZip's archive extraction process does not properly transfer the Zone.Identifier alternate data stream from the parent archive to extracted child files. This represents an incomplete remediation of the earlier CVE-2024-8811 vulnerability, suggesting that the original patch did not fully address all scenarios where MotW propagation should occur.

Attack Vector

The attack vector requires user interaction through a network-based delivery mechanism. An attacker would need to craft a malicious archive containing executable or script content and distribute it via email, malicious websites, or other download mechanisms. When a victim downloads the archive, Windows correctly applies the Mark-of-the-Web to the archive file. However, when the victim uses WinZip to extract the contents, the extracted files lose their MotW designation, allowing them to execute without the usual security warnings that would alert users to potentially dangerous content from untrusted sources.

The vulnerability can be exploited to execute arbitrary code in the context of the current user, which could lead to system compromise, data theft, or further malware deployment depending on the user's privileges and the nature of the malicious payload.

Detection Methods for CVE-2025-33028

Indicators of Compromise

• Extracted executable files lacking Zone.Identifier alternate data streams despite originating from downloaded archives
• Unusual process execution originating from directories commonly used for archive extraction (e.g., Downloads, Temp)
• Execution of unsigned or untrusted binaries without corresponding Windows SmartScreen or security warning events

Detection Strategies

• Monitor for execution of files extracted by WinZip that lack the expected Zone.Identifier metadata
• Implement endpoint detection rules to flag executable content extracted from archives that bypass MotW warnings
• Use file integrity monitoring to track the presence or absence of alternate data streams on newly created files

Monitoring Recommendations

• Deploy SentinelOne endpoint protection to monitor for suspicious execution patterns following archive extraction
• Enable detailed logging for WinZip operations and correlate with process execution events
• Implement behavior-based detection for code execution following archive extraction without corresponding security warning events

How to Mitigate CVE-2025-33028

Immediate Actions Required

• Review and update WinZip to the latest available version by checking the WinZip Release Notes
• Implement application control policies to restrict execution of content from common extraction directories
• Educate users about the risks of extracting and executing content from downloaded archives
• Consider using alternative archive utilities that properly propagate Mark-of-the-Web attributes

Patch Information

Organizations should monitor WinZip's official release notes and security advisories for patches addressing this incomplete fix. Review the WinZip Release Notes for the latest updates. Given that this vulnerability is an incomplete fix for CVE-2024-8811, ensure that any patches specifically address the MotW propagation issue.

Workarounds

• Use Windows built-in archive extraction capabilities which properly handle Mark-of-the-Web propagation
• Implement Group Policy settings to enforce SmartScreen checks regardless of MotW status
• Deploy endpoint protection solutions that can detect and block malicious executables based on behavior rather than relying solely on MotW warnings
• Configure email gateways and web proxies to scan archive contents before delivery to end users

# Check for Zone.Identifier on extracted files using PowerShell
# Run this to verify if MotW is present on extracted files
Get-Item -Path "C:\Users\*\Downloads\extracted_file.exe" -Stream Zone.Identifier -ErrorAction SilentlyContinue

# Alternative: Use dir to check for alternate data streams
dir /r "C:\Users\*\Downloads\extracted_file.exe"