Malicious actors continue to exploit LNK files in ongoing malware attacks, capitalizing on a fundamental vulnerability that obscures harmful content from users. As Microsoft has yet to address this vulnerability, vigilance is necessary when dealing with LNK files. This guide provides crucial steps to safeguard against potential abuses of these file types.
Understanding LNK Files: The Risks They Pose
LNK files, often generated as shortcuts within the Windows operating system, carry the.lnk extension. You may be familiar with creating or allowing applications to create these desktop shortcuts; however, it’s crucial to note that Windows conceals the.lnk extension, replacing it with a distinctive sideways arrow icon.
These shortcuts direct users to the designated file or application but possess an alarming capability—their target field can be manipulated to include command-line instructions. This feature enables cybercriminals to execute harmful scripts, often used in fileless attacks exemplified by malware such as Astaroth.
What’s particularly dangerous is that attackers can obscure malicious scripts by utilizing excessive whitespace in the target field. Consequently, users may only see a benign target address, while harmful instructions are executed in the background. This vulnerability is tracked under the ID: CVE-2025-9491.
Typically, a deceptive.lnk file is concealed within an archive, featuring a misleading name like “Instructions.pdf.ink.” Because Windows omits the file extension visibility, users might mistakenly identify it as “Instructions.pdf” and unknowingly initiate the attack upon opening.
Revealing LNK File Extensions in Windows
The first line of defense against such threats is recognizing LNK files as shortcuts rather than genuine files. Since LNK files are designed to function within a local or networked environment, any unsolicited LNK file from external sources is likely a phishing attempt.
To enhance the identification of LNK files, you can configure Windows to display the.lnk extension. This requires a registry modification, as the standard file extension toggle does not apply to.lnk files. Begin by enabling the Show file extensions option in the system settings, then apply the following registry change:
Important: Create a backup of your Registry before making any alterations. Incorrect changes may lead to system instability or data loss.
Access the Registry and navigate to:
HKEY_CLASSES_ROOT\lnkfile
Once there, locate and delete the NeverShowExt string. Restart your PC for the changes to take effect. Afterward, all shortcuts will display the.lnk extension. Be cautious, and do not open any file claiming to be a.ink file.
Analyzing LNK Files for Safety
If you encounter a suspicious LNK file, a careful examination of its target field is advisable. Right-click the file and select Properties. In the Shortcut tab, examine the Target field closely.
A legitimate shortcut should display the precise path to the executable file within quotes. If the path leads to command tools like cmd.exe, powershell.exe, or mshta.exe, it may indicate malicious intent. Additionally, the presence of random characters or binary sequences at the end of the string can suggest nefarious activity.
Disabling AutoPlay and File Previews
Historically, Windows AutoPlay features for USB drives and file preview options within File Explorer have been vulnerable to exploitation via LNK files. Although Microsoft has improved security measures, these features still pose risks. If they are not essential to your workflow, consider disabling them for enhanced safety.
To disable AutoPlay, navigate to Windows Settings → Bluetooth & devices → AutoPlay, and toggle the switch to turn it off. For information on managing file preview settings, refer to our comprehensive guide.
Activating Controlled Folder Access
Controlled Folder Access is a Windows feature designed to protect critical folders—such as Documents, Pictures, and Desktop—against unauthorized changes, particularly from ransomware attacks. Given that many LNK file attacks target these directories for malicious actions, enabling this feature adds a crucial layer of security. For detailed instructions on activation, please refer to our guide.
Strengthening PowerShell Security
LNK file attacks often leverage PowerShell commands to execute harmful actions. To mitigate this risk, restrict PowerShell operations to signed scripts only. Type “powershell” in the Windows search bar, right-click the application, and select Run as administrator. Enter the following command, confirming the change by typing “y.”
Set-ExecutionPolicy AllSigned
Be aware that this setting may hinder workflows reliant on custom PowerShell scripts, particularly in corporate settings. To revert this change, use:
Set-ExecutionPolicy Undefined
Additionally, refer to our guide for supplementary tips on securing PowerShell further.
A prudent rule of thumb: avoid opening LNK files unless you created them or authorized their creation through a trusted application. This caution is particularly relevant for files downloaded from the internet. Always utilize Windows security features for maximum protection, especially if some have been disabled.
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