Windows System Software -- Consulting, Training, Development -- Unique Expertise, Guaranteed Results

Home NTFSD

Before Posting...

Please check out the Community Guidelines in the Announcements and Administration Category.

More Info on Driver Writing and Debugging


The free OSR Learning Library has more than 50 articles on a wide variety of topics about writing and debugging device drivers and Minifilters. From introductory level to advanced. All the articles have been recently reviewed and updated, and are written using the clear and definitive style you've come to expect from OSR over the years.


Check out The OSR Learning Library at: https://www.osr.com/osr-learning-library/


On-access real time anti-virus minifilter

x90x90x90x90x90x90 Member Posts: 1
edited September 2020 in NTFSD

Hi all,

I'm trying to write an anti-virus which scans file's content when file operations are performed on them.
I've followed the avscan sample of Microsoft and added some stuff of my own.
The Microsoft sample scans the file when it is opened (IRP_MJ_CREATE) and when it is closed if the file was modified (IRP_MJ_CLEANUP).

After running the sample multiple times I witnessed the performance hit caused by this minifilter, since it scans almost every opened file.

Any ideas how to minimize the performance hit?

Sign In or Register to comment.

Howdy, Stranger!

It looks like you're new here. Sign in or register to get started.

Upcoming OSR Seminars
OSR has suspended in-person seminars due to the Covid-19 outbreak. But, don't miss your training! Attend via the internet instead!
Writing WDF Drivers 12 September 2022 Live, Online
Internals & Software Drivers 23 October 2022 Live, Online
Kernel Debugging 14 November 2022 Live, Online
Developing Minifilters 5 December 2022 Live, Online