A vulnerability in WinRAR that allowed malicious files to be executed without security alerts has been detected and fixed.

A recent announcement has been made vulnerability in WinRAR, one of the oldest and most popular file compression tools in the world, which allowed attackers to evade one of the most important security mechanisms of the Windows operating system: the so-called Mark of the Web (MotW). This security flaw exposed users to potential dangers by executing malicious files without any warnings from the system..

According to cybersecurity experts, This vulnerability affects all versions of the program prior to 7.11 and has been officially registered under the code CVE-2025-31334. The discovery was made by Shimamine Taihei, a researcher at the Japanese cybersecurity firm Mitsui Bussan Secure Directions, who alerted the public to the issue through Japan's Information Technology Promotion Agency (IPA).

The flaw in detail: how to bypass Windows protection

The vulnerability lies in WinRAR's handling of symbolic links, known as symlinks., which are files that act as shortcuts to other files or directories. When a compressed file contains one of these symlinks pointing to an executable, and is opened from a vulnerable version of WinRAR, The system ignores the Web Brand associated with the file.

La Web Brand It is a security system specific to Windows that adds a special label to files downloaded from the Internet, warning the user that the content may be dangerousNormally, when you open a file with this flag, Windows warns you of its origin and requests confirmation before allowing it to run.

With this ruling, Attackers can execute malicious code without raising suspicion, which makes users more vulnerable to infections, data theft, or even the silent installation of dangerous programs on their computers. All of this happens without the operating system displaying any warning window.

Importantly For symlinks to be effective, they must be created with administrator privileges on the operating system., so the attacker would have already achieved some level of access or deception towards the victim.

Impact of vulnerability and its severity

La vulnerability has been classified with a score ofand 6,8 out of 10 on the CVSS scale (Common Vulnerability Scoring System), which places it at a medium severity level. However, specialists agree that its potential for use in malware campaigns makes it especially dangerous if measures are not taken in time.

These types of mechanisms have already been exploited previously by cybercriminal groups, as occurred in a recent case in which a Similar vulnerability in the 7-Zip program used to distribute Smokeloader, a well-known malware loader. In that case, the attackers used double compression techniques to bypass MotW warnings and execute the code without any user notification. For more information on other compression programs, you can visit this link about compression programs.

The current situation of WinRAR is not very different, since It is also a widely used tool and used in both domestic and corporate settings. This increases the risk that the flaw will be widely exploited before users update their systems.

How to Protect Yourself: Essential Update

The solution to this problem has already been published by the developers of WinRAR through the version 7.11 of the programThis update fixes the behavior of symlinks to ensure that executable files flagged by MotW continue to display the appropriate warning when opened.

Upgrade to Version 7.11 is the only way to protect the system against this specific vulnerability.Experts recommend performing the update as soon as possible and preferably from the WinRAR official website, thus avoiding modified versions or versions distributed by third parties that could contain malicious software.

Furthermore, It is advisable to regularly check which version of the software is installed, especially in environments where sensitive information is handled or large amounts of files are received over the Internet. Keep applications up to date It is one of the most effective practices to prevent security problems.

WinRAR developers have reported that this fix is ​​included in the 7.11 release notes, along with other minor tweaks and improvements, so there's no reason not to proceed with the installation as soon as possible.

Lessons and broader security context

This incident once again highlights the Importance of cybersecurity in everyday toolsSeemingly harmless programs, such as file compression tools, can hide dangers if a vulnerability is discovered and exploited before patches are available or applied.

The case of WinRAR is not isolated, as demonstrated by what happened with other similar utilities. The recurrence of methods based on circumventing the Mark of the Web (MotW) indicates that attackers are well aware of its weaknesses and are looking for new ways to exploit them. If you'd like to learn more about how to encrypt a file, you can check out this specific article.

Beyond the error itself, The worrying thing is the ease with which users can fall victim. simply by opening a seemingly harmless compressed file. This highlights not only the technical function of the patch but also the importance of awareness among end users.

Businesses and individual users should take a preventative approach, carrying out Frequent updates and avoiding downloading software or files from unreliable sourcesUsing behavioral analysis tools and updated antivirus software can also help mitigate the risk.