Microsoft takes precautions against the hidden danger targeting Windows users

Microsoft has implemented new measures targeting an important security vulnerability related to remote desktop connections in the April 2026 cumulative updates released for Windows 10 and Windows 11. The update aims to make it harder to abuse RDP (Remote Desktop Protocol) files, which are widely used especially in corporate environments. This new structure, which provides information to the user at the first stage and then offers detailed control before each connection, focuses on preventing attackers from gaining secret access to systems.

RDP files, which are frequently used in corporate IT infrastructures, enable administrators to connect to remote systems quickly and in a pre-configured way. Despite this, the same structure can also be exploited by malicious people. An RDP file that the user unknowingly opens can cause the device to connect to an attacker-controlled server. In such a scenario, sensitive content such as local disks, clipboard data and authentication information can be transferred to the other party.

This risk is not just a theoretical possibility. A cyber attack group called APT29, which is said to be linked to Russia, has seized user data by using malicious RDP files in phishing campaigns it has organized in the past. The main reason why this method is effective is that the attack looks like an ordinary file opening process and does not arouse suspicion in the user.

Windows displays an “Unknown remote connection” warning when an unsigned RDP file is opened, indicating that the publisher cannot be verified. On the other hand, even if the file is digitally signed, the system continues to request the user to check the publisher before connecting. Microsoft takes a more cautious approach by not accepting the digital signature alone as an indicator of trust.

Multi-layered security approach for Windows RDP files

With the new update, security mechanisms work in several stages. When an RDP file is opened for the first time after the update, Windows presents the user with an informative screen explaining how these files work and what risks they pose. This screen is shown only once, and after user approval, the normal usage process begins.

Afterwards, a detailed security window is activated every time an RDP file is opened. In this window, whether the file is signed by a trusted publisher, the address of the remote system to be connected to, and the local resources to which access is requested are clearly listed. Elements such as local disks, clipboard access, and connected devices are kept off by default. The user must give explicit permission to share these resources.

However, these protections only apply when the RDP file is opened directly. In connections established through Windows’ own Remote Desktop client, the current experience is preserved and additional warnings do not come into play. System administrators can temporarily disable these warnings via the registry if they wish. However, considering the examples of attacks in the past, keeping these protections active provides safer use.