File Protector, File Control Filter Driver SDK

Develop File Access Control or File Protector Application with Control Filter Driver SDK

EaseFilter file system filter driver is a kernel-mode component that runs as part of the Windows executive above the file system. The EaseFilter file system filter driver can intercept requests targeted at a file system or another file system filter driver. By intercepting the request before it reaches its intended target, the filter driver can extend or replace functionality provided by the original target of the request. The EaseFilter file system filter driver can log, observe, modify, or even prevent the I/O operations for one or more file systems or file system volumes.

file access control

File Access Control and File Protection

The EaseFilter file protector can prevent your sensitive files from being accessed by unauthorized user. With the EaseFilter file protector you can control the file I/O activities on file system level, capture file open, create, overwrite, read, write, query file information, set file information, query security information, set security information, file rename, file delete, directory browsing and file close I/O requests.

EaseFilter file protector provides a comprehensive security solution for transparent file level encryption. It allows the file to be encrypted or decrypted transparently on-the-fly, every file will be encrypted with the unique encryption iv key, it can allow only authorized users or processes can access the encrypted files.

Setup File Protection Policies with Different File Filter Rules

To monitor or protect your file folder, you need to setup multiple file filter rules. In the file filter rule, you have to setup the file filter mask which is the unique index of the filter rule, you can setup the what processes or users can monitor the file I/O, you can filter the file I/O with the file open options, you can register the file change events or register the specific file I/Os.

Filter rule setting

File Access Control Flag Settings of the File Filter Rule

To control the file access and protect your sensitive data, you can configure the access control flag in the filter rule, or you can register the pre-io events, allow or deny the file access in the pre-io notification event. To configure the access flag of the filter rule, you can prevent your files from being read, written, deleted, renamed or changed by unauthorized processes or users.

access control

Set the access flag to control the file access in the file filter rule

With the access flag of the filter rule, you can use every bit of the access flag integer to allow or block the specific I/O as below to run.

file access control flags

Set the access rights to the specific processes or users in the file filter rule

With the access rights setting, you can add or remove the access rights to the specific processes or users in the file filter rule. So, you can authorize the users or processes to access your protected files, you also can prevent your protected files from being accessed by the unauthorized users or processes.

Register the file I/O events to control the file access in the file filter rule

By registering the specific I/O events, you can fully control the I/O, your callback functions will be invoked for every registered I/O, you can allow, modify or block this I/O based on the I/O information.

control file io events

The File Protector Console

In the file protector console, you can see the denied I/O information or the callback control I/O notification information as below:

file protector console

A File Protector C# Example

The following example creates a filter rule to protect the directory specified at run time. The filter rule was set to protect the folder against the file being renamed, deleted, written. The component is registered with the create and delete IO callback event in the directory. If a file was opened or deleted, the event will be triggered, you can allow or block the IO in the event.

using System;
using EaseFilter.FilterControl;

namespace FileProtectorConsole
    class Program
        static FilterControl filterControl = new FilterControl();

        static void Main(string[] args)
            string lastError = string.Empty;
            string licenseKey = "Email us to request a trial key:";

            FilterAPI.FilterType filterType = FilterAPI.FilterType.MONITOR_FILTER|FilterAPI.FilterType.CONTROL_FILTER

            int serviceThreads = 5;
            int connectionTimeOut = 10; //seconds

                //copy the right Dlls to the current folder.
                Utils.CopyOSPlatformDependentFiles(ref lastError);

                if (!filterControl.StartFilter(filterType, serviceThreads, connectionTimeOut, licenseKey, ref lastError))
                    Console.WriteLine("Start Filter Service failed with error:" + lastError);

                //the watch path can use wildcard to be the file path filter mask.i.e. '*.txt' only monitor text file.
                string watchPath = "c:\\test\\*";

                if (args.Length > 0)
                    watchPath = args[0];

                //create a file protector filter rule, every filter rule must have the unique watch path. 
                FileFilter fileProtectorFilter = new FileFilter(watchPath);

                //configure the access right for the protected folder

                //prevent the file from being deleted.
                fileProtectorFilter.EnableDeleteFile = false;

                //prevent the file from being renamed.
                fileProtectorFilter.EnableRenameOrMoveFile = false;

                //prevent the file from being written.
                fileProtectorFilter.EnableWriteToFile = false;

                //authorize process with full access right
                fileProtectorFilter.ProcessNameAccessRightList.Add("notepad.exe", FilterAPI.ALLOW_MAX_RIGHT_ACCESS);

                //you can enable/disalbe more access right by setting the properties of the fileProtectorFilter.

                //Filter the callback file IO events, here get callback before the file was opened/created, and file was deleted.
                fileProtectorFilter.ControlFileIOEventFilter = (ulong)(ControlFileIOEvents.OnPreFileCreate | ControlFileIOEvents.OnPreDeleteFile);

                fileProtectorFilter.OnPreCreateFile += OnPreCreateFile;
                fileProtectorFilter.OnPreDeleteFile += OnPreDeleteFile;


                if (!filterControl.SendConfigSettingsToFilter(ref lastError))
                    Console.WriteLine("SendConfigSettingsToFilter failed." + lastError);

                Console.WriteLine("Start filter service succeeded.");

                // Wait for the user to quit the program.
                Console.WriteLine("Press 'q' to quit the sample.");
                while (Console.Read() != 'q') ;


            catch (Exception ex)
                Console.WriteLine("Start filter service failed with error:" + ex.Message);


        /// Fires this event before the file was opened. 
        static void OnPreCreateFile(object sender, FileCreateEventArgs e)
            Console.WriteLine("OnPreCreateFile:" + e.FileName + ",userName:" + e.UserName + ",processName:" + e.ProcessName);

            //you can block the file open here by returning below status.
            e.ReturnStatus = NtStatus.Status.AccessDenied;


        /// Fires this event before the file was deleted.
        static void OnPreDeleteFile(object sender, FileIOEventArgs e)
            Console.WriteLine("OnPreDeleteFile:" + e.FileName  + ",userName:" + e.UserName + ",processName:" + e.ProcessName);

            //you can block the file being deleted here by returning below status.
            e.ReturnStatus = NtStatus.Status.AccessDenied;