CVE-2025-33028 is a vulnerability in WinZip versions up to 29.0 involving the improper handling of the Mark-of-the-Web (MotW) security feature. MotW is a Windows security mechanism designed to mark files downloaded from the internet or other untrusted sources, thereby restricting their execution or prompting security warnings to prevent inadvertent execution of potentially malicious content. This vulnerability stems from an incomplete fix for a previous issue (CVE-2024-8811) and specifically affects how WinZip processes archived files bearing the MotW attribute. When a user extracts files from a crafted archive marked with MotW, WinZip fails to propagate this security attribute to the extracted files. Consequently, these files lose the MotW protection, allowing them to be executed without the usual Windows security prompts or restrictions. Exploiting this flaw requires user interaction, such as opening a malicious archive or visiting a malicious webpage that delivers such an archive. An attacker can leverage this behavior to execute arbitrary code under the context of the current user, potentially leading to unauthorized actions or further compromise. The vulnerability is classified under CWE-830, which concerns the inclusion of web functionality from untrusted sources, highlighting the risk of executing untrusted content without proper security checks. The CVSS v3.1 base score is 6.1 (medium severity), reflecting that the attack vector is network-based with low complexity, no privileges required, but user interaction is necessary. The impact affects confidentiality and integrity but not availability, and the scope is changed due to the potential for code execution beyond the initial component. No known exploits are currently reported in the wild, and no patches have been linked yet, indicating that organizations should be vigilant and prepare for remediation once available.

For European organizations, this vulnerability poses a tangible risk, especially in environments where WinZip is widely used for handling compressed files. The ability to bypass MotW protections can facilitate the execution of malicious payloads delivered via seemingly benign archives, increasing the risk of malware infections, data breaches, or lateral movement within networks. Since the attack requires user interaction, phishing campaigns or social engineering tactics could be employed to trick users into opening malicious archives. This risk is heightened in sectors with high reliance on file sharing and document exchange, such as finance, legal, healthcare, and government institutions. The compromise of user accounts through arbitrary code execution can lead to unauthorized access to sensitive data, intellectual property theft, or disruption of business processes. Additionally, the failure to propagate MotW undermines a critical layer of defense in Windows security, potentially allowing attackers to evade endpoint protection mechanisms that rely on this attribute. Given the medium severity and the widespread use of WinZip in Europe, the vulnerability could be exploited to target organizations with valuable data or critical infrastructure, especially if combined with other attack vectors.

European organizations should implement a multi-layered approach to mitigate this vulnerability effectively. First, they should monitor vendor communications closely and apply patches or updates from WinZip as soon as they become available, as no official patch links are currently provided. Until a patch is released, organizations can enforce policies to restrict the use of WinZip for extracting files from untrusted sources or disable automatic extraction features. User education is critical; training users to recognize suspicious archives and avoid opening files from unverified sources can reduce the risk of exploitation. Endpoint protection solutions should be configured to detect and block execution of files lacking MotW or exhibiting suspicious behavior post-extraction. Network-level controls, such as email filtering and web gateway protections, should be enhanced to detect and quarantine malicious archives before reaching end users. Additionally, organizations can implement application whitelisting and restrict execution privileges to minimize the impact of arbitrary code execution. Regular audits of file handling procedures and security configurations related to MotW enforcement can help identify gaps. Finally, incident response plans should be updated to include scenarios involving MotW bypass exploitation to ensure rapid detection and containment.