3 Free NirSoft Tools for Malware Analysis

Nir Sofer makes a number of Windows utilities, which he distributes for free on the NirSoft website. This post takes a quick look at 3 of his tools—ProcessActivityView , RegFromApp and ProcessThreadsView—which can be handy when analyzing malware from a behavioral perspective. These programs can be a useful supplement to Microsoft’s Process Monitor and Process Explorer tools.


ProcessActivityView delineates which files and folders the designated process attempts to access. It allows you to begin tracing an existing process by letting use select from an active process listing:

The tool also allow you to start a new process and begin tracing it immediately:

ProcessActivityView displays a real-time log of the file system activity associated with the monitored process. In addition to displaying the file path, the tool displays tracks how many times the file was opened, how many bytes were read and written, etc. It also displays the DLL that made the last open-file call:


RegFromApp monitors registry activities of the designated process, displaying a log file of registry changes. This can be a quick way to observe how a malicious program attempts to change the registry:

Like with ProcessActivityView, you can point RegFromApp to an existing process or tell it to launch the specified executable and begin tracing it immediately.


ProcessThreadsView is designed similarly to ProcessActivityView and RegFromApp, letting you monitor existing processes or trace new ones. When active, this tool displays information about the threads of the designated process, including strings found on the stack of each thread and much more:

Good Supplement to Other Tools

ProcessActivityView, RegFromApp and ProcessThreadsView are quick and easy to use to give you some visibility into registry and file system capabilities of malicious programs. However, they generally aren’t as comprehensive as Process Monitor, to some extent, Process Explorer. I consider them “second opinion” tools, and like having them as part of my malware analysis toolkit.

Hand-picked related items:

Just so you know, I teach the malware analysis course at SANS Institute.

Lenny Zeltser


About the Author

Lenny Zeltser develops products and programs that use security to achieve business results. He is the CISO at Axonius and Faculty Fellow at SANS Institute. Lenny has been leading efforts to establish resilient security practices and solve hard security problems for over two decades. A respected author and practitioner, he has been advancing tradecraft and contributing to the community. His insights build upon real-world experience, a Computer Science degree from the University of Pennsylvania, and an MBA degree from MIT Sloan.

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