How to Find and Remove WMI Persistence Malware From a Windows PC

WMI persistence malware can hide on your computer in plain sight. Fortunately, it’s easy to get rid of it from a Windows PC.

Microsoft created Windows Management Instrumentation (WMI) to handle how Windows computers allocate resources in an operational environment. WMI also does another important thing: it facilitates local and remote access to computer networks.

Unfortunately, black hat hackers can hijack this capability for malicious purposes through a persistence attack. As such, here’s how to remove WMI persistence from Windows and keep yourself safe.

What Is WMI Persistence, and Why Is it Dangerous?

WMI persistence refers to an attacker installing a script, specifically an event listener, that is always triggered when a WMI event happens. For instance, this will occur when the system boots or the system administrator does something on the PC, like opening a folder or using a program.

Persistence attacks are dangerous because they are stealthy. As explained on Microsoft Scripting, the attacker creates a permanent WMI event subscription that executes a payload that works as a system process and cleans up logs of its execution; the technical equivalent of an artful dodger. With this attack vector, the attacker can avoid getting discovered through command-line auditing.

How to Prevent and Remove WMI Persistence

WMI event subscriptions are cleverly scripted to avoid detection. The best way to avoid persistence attacks is to disable the WMI service. Doing this should not affect your overall user experience unless you’re a power user.

The next best option is to block the WMI protocol ports by configuring DCOM to use a single static port and blocking that port. You can check out our guide on how to close vulnerable ports for more instructions on how to do this.

This measure lets the WMI service run locally while blocking remote access. This is a good idea, especially because remote computer access comes with its own share of risks.

Finally, you can configure WMI to scan and alert you to threats, as Chad Tilbury demonstrated in this presentation:

A Power That Should Not Be in the Wrong Hands

WMI is a powerful system manager that becomes a dangerous tool in the wrong hands. Worse still, technical knowledge is not needed to carry out a persistence attack. Instructions on creating and launching WMI persistence attacks are freely available on the internet.

So, anyone with this knowledge and brief access to your network can remotely spy on you or steal data with barely a digital footprint. However, the good news is there are no absolutes in technology and cybersecurity. It is still possible to prevent and remove WMI persistence before an attacker does great damage.

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