How to Detect and Avoid Malicious EXE Files on Windows

Cybercriminals often use malicious EXE files to spread malware, ransomware, or spyware. That's why it's important to be able to recognize and avoid potentially harmful files to protect your device from infection. If you suspect a file might be unsafe, there are a few ways to check it before using it.

1. Check file name, extension, size and source

Checking the key properties of a file can help you identify potentially malicious EXE files. Start by checking the file name and extension. If the file has a generic name like 'install.exe' or 'update.exe' instead of the expected name, or if the file uses a double extension (for example, 'file.pdf.exe'), that could be a red flag.

File size can also be an indicator. Files that are unusually small or too large compared to the usual size of the desired program may be malicious. To reduce the risk of infection, always download files from official sources and avoid executable files received via unsolicited emails or social media links.

2. Run the file through antivirus software

If you try to open or download an EXE file and your antivirus software gives you a warning, take that warning seriously. Instead of downloading it immediately, run a scan of the specific file using Microsoft Defender. If you are using a third-party antivirus, right-click the file and select the option to scan it with your installed program.

If the scan flags the file as suspicious or malicious, delete it immediately to protect your system. Never run a suspicious file 'just to see' if it's safe; this can lead to data theft, malware, and other security issues. Also, keep your antivirus software enabled so you're alerted immediately if any potentially harmful files are found on your computer.

While Windows Defender usually detects threats and automatically alerts you, it's a good idea to install third-party antivirus software on your system for added protection.

3. Analyze files with VirusTotal

If you want to check if an executable file is malicious without downloading it, try using VirusTotal. This online tool scans files and URLs using multiple antivirus engines and databases to provide a detailed report of potential threats. This can prevent you from downloading a potentially harmful EXE file.

To use this tool:

1. .
2. Select the URL tab , paste the URL where the file is stored and press Enter . VirusTotal will then display results from multiple antivirus engines.

If you detect a threat, avoid downloading the file. If you have already downloaded it, you can also upload the file directly to VirusTotal to scan it for malware.

4. Check digital signature

You can also verify the authenticity of an EXE file by checking its digital signature. This is essentially a 'stamp of approval' from the software publisher, confirming that the file has not been altered since it was signed. Be cautious if the file does not have a digital signature or lists an unexpected publisher.

To view digital signature:

1. Right-click on the EXE file and select Properties .
2. Go to the Digital Signatures tab . Select the signature, click Details , then View Certificate to check the issuer.

If it shows a trusted publisher, go to the Certification Path tab to confirm there is a "This Certificate Is OK" message there.

5. Make sure Windows SmartScreen Protection is turned on

Windows SmartScreen is a built-in security feature that checks files and apps against a threat database, warning you of potential risks when handling suspicious files or apps on your computer. While this feature is usually enabled by default on Windows 10/11, you should double-check that the SmartScreen filter is enabled.

To verify SmartScreen is turned on:

1. Right-click the Start button and open Settings .
2. Then, navigate to Privacy & Security > Windows Security > Apps & browser control , and click Reputation-based protection settings .
3. Make sure all 4 filters are enabled, especially the Check apps and files filter .

That's how you can identify a malicious EXE file. If you use official sources and follow the steps above, you can easily spot suspicious files and help keep your computer safe.

Marvin Fry

Update 09 December 2024