Everyone knows that when you delete a file in Windows it is first moved to the Recycle Bin. When the file is deleted from the Recycle Bin it is not completely gone but the space on the drive occupied by the file has been marked as available to be overwritten. That means the file’s data is still there and can actually be recovered using free data recovery software until it is overwritten by something else.
There are some dedicated tools to permanently wipe or shred the files to prevent them from being recovered as they are deleted. However, once the file has been emptied from the Recycle Bin, Windows does not offer a simple way to restore it back so the file can be shredded. Over time, the amount of data still readable from previously deleted files can become huge.
The image above shows a deleted sensitive file is still viewable in a Hex editor. A good way around this is to use a free utility that is able to make all recoverable data unrecoverable. This is done by erasing only the space on your drive that is not currently occupied by existing files. Once that is done, old data can no longer be seen or recovered. Here’s a selection of 10 free tools to securely wipe free disk space.1. Eraser
Erase is a well known and popular tool to permanently and securely wipe data. This includes wiping files, folders, drives, partitions, secure file moving, and wiping empty space. It’s a bit more complicated to run a simple wipe in Eraser than other tools because it works on the basis of schedules and you have to create a schedule to do anything.
Run the program, right click in the Erase Schedule box, and select New Task. Click the Add Data button, select the “Unused disk space” from the “Target type” drop down, select the “Erasure method”, then choose the drive from the list and click OK twice. A new task is added to the schedule, Right click and select “Run Now” to start the task. Different drives or different wipe algorithms will require different schedules.
If you leave the erase method on default for any drive wiping functions it will perform a random data single pass erase. This can be changed in the Settings to something different if you have a favorite method. There are 12 separate erase algorithms to choose, including a single pass of zeros or random data, 2 pass GOST, 3 pass DOD, 7 pass VSITR, and the 35 pass Gutman method.
Hardwipe is a well known and fully featured tool for erasing files or wiping drives before they are given to or sold to other users. One of its functions is to clean the free space of drives using several different wiping methods. Hardwipe has to be installed as the portable version went payware some years ago. There’s also an ad for the paid version in the main user interface although it’s not overly intrusive.
Select “Free space” from the left side icons and then you can select one or more drives to have their free space wiped. There are seven cleaning methods; 1 pass zero fill, 1 pass random data, 2 pass GOST R 50739-95, 3 pass DOD 5220.22-M, 7 pass VSITR, 7 pass Schneier, and 35 pass Gutmann. The RAZER methods are only available in the paid version.
There’s also a drop down menu for logging off or shutting the computer down on completion. The speed option is useful if you are wiping a partition’s space while using another partition on the same physical drive. This will intentionally slow down the wiping speed to make the drive more responsive.
3. Sysinternals SDelete and Raymonodcc Free Space Wiper Frontend
SDelete is by Microsoft owned developer Sysinternals. The program is command line only and can also be used to securely erase files as well as wiping available drive space. The two wiping methods available are filling the free space with zeros or a DOD 5220.22-M erase that fills the space with zeros, ones, then random data. Open a Command Prompt or PowerShell window and type the command.
SDelete -c C:
SDelete -p 2 -z C:
The top command runs the three pass DOD method (-c) on drive C, use any drive letter you need to. The bottom command performs the zero fill (-z) but also uses the optional passes argument (-p) to run the pass twice. The zero fill option is useful and often recommended for zeroing virtual hard disks for optimization.
Raymonodcc Free Space Wiper Frontend
SDelete is not difficult to use but many users prefer not to deal with Command Prompt or manually typed commands. As a result, we created a small tool to accomplish the task. It’s portable and simple to use and requires SDelete.exe to work. For best results place SDelete(64).exe in the same folder as the tool, in the Windows folder, or in the System32 folder. Otherwise, you will be asked to locate the executable.
All you have to do is select the drive to clean from the drop down, select the three pass clean or the zero method, and press the run button. You can also increase the number of passes but remember the Clean option already runs a triple pass algorithm. The program runs SDelete in a console window with the required arguments.
You’ll notice the tool has two tabs, one for SDelete and another called Cipher, more information can be found for that tab on page two of this article. Free Space Wiper Frontend is only 35KB in size and requires .NET Framework 4 which is in Windows 10 and 8 by default. Any useful feedback you have can be left in the comments.
CCleaner is probably the most famous Windows junk file cleaning utility around. It also offers a function called Drive Wiper to securely erase entire drives or the free space on your drives. Go to Tools > Drive Wiper, and make sure “Free Space Only” is selected for the wipe option. Then select the overwrite method and finally the drive(s) that you want to wipe.
The CCleaner Drive Wiper has 4 wiping techniques which are 1 pass zero, 3 pass DOD 5220.22-M, 7 pass NSA, and the 35 pass Gutmann method. Simply press Wipe and you’ll get a progress bar with an estimated time to completion. CCleaner comes as a portable version or a setup installer.
5. Hard Disk Scrubber
Disk Scrubber is from 2011 and is a very simple tool to operate with a nice and clean user interface. In addition to free space cleaning, the program can also securely erase files and folders. Disk Scrubber has a rather novel feature of letting you create your own erase algorithm along with your own custom writing pattern.
For simple free space wiping, all you have to do is select the drive from the list, choose the erasing method, and click “Scrub Drive”. The built in methods are Normal 1 pass random data, Heavy 3 pass (equivalent to DOD 5220.22-M), Super 5 pass, and Ultra 9 pass (essentially three DOD 5220.22-M passes and verify). However, the last option of Custom is the most interesting.
Click Edit and a new window opens where you can create your own erasing method. Enter the patterns you want to use in the bottom text box in the order they are to be used. Zeros, ones, checkerboard, random, and a custom pattern can be used in any combination. Type your own text into the top text box for the custom pattern. The image above uses zeros, “NOTHINGTOSEEHERE!”, then random for a three pass erase.
6. File Shredder
File Shredder, as its name suggests, is a free tool meant for shredding single and multiple files including free disk space with Windows shell right click integration. To wipe the free disk space, run File Shredder and click on “Shred Free Disk Space” at the left pane. A new window will open where you can select the disk to wipe and the algorithm to use. Click the Next button and then Start.
File Shredder supports 5 types of wiping algorithm which are a single pass of zeros, 2 passes, DOD 5220.22-M (3 passes), 7 passes, and the paranoid Gutmann 35 passes. Make sure to press the back button once the process has finished or you’ll start the wipe again.
7. Moo0 Anti-Recovery
Moo0 Anti-Recovery is a free and very easy to use program that cleans the empty spaces on a drive with random data. Install the program, then you only need to select the drive that you want to process from the drop down, the other options can be left alone if you are not sure. The version we used offered two of their other tools during install, so make sure you pay attention to the install process.
The options to empty the recycle bin, clear free space in the MFT (Master File Table), and wipe the cluster tips are enabled by default. The fifth option of clearing file name traces from the MFT is not selected by default and the program notes it could take some time. The random data is written to the free space once, which should be fine for most normal drives and situations.
8. ASCOMP Secure Eraser
Secure Eraser is free for non commercial use and it has a number of useful options to securely erase data. These include erasing junk files, registry cleaning, file/folder erasing, drive and partition erasing, and drive free space cleaning. The free version doesn’t appear to be feature limited but it does pop up a nag window when any task has been completed.
Press the “Free space deletion” button in the main window and click on the required drive to highlight it. When the “Start deletion” button is pressed you will be presented with the wipe methods on offer. They are 1 pass random data, 3 pass DOD 5220.22-M, 7 pass German standard, 7 pass extended DOD 5220.22-M, and the famous 35 pass Gutmann method.
Three extra options of clean MFT, clean USN Journal, and overwrite slack space are enabled by default. There’s probably no need to change them unless you know what you are doing. The small blue buttons above the start button are for shutting down the computer or exiting the program on completion.
BleachBit is a free and well-known utility for cleaning junk files from your computer. There are two ways to wipe free space using BleachBit. The first is to click the top left Options menu, select “Wipe Free Space” and choose a folder on the drive. The second method is to check “Free disk space” from the System category and click the Clean icon.
The program requires you to select a folder on the drive as opposed to just the drive letter or the clean will fail. Using the Options menu, you can choose a folder from the dialog. To use the Clean option you have to go to Options > Preferences > Drives and add a folder manually to the list. An entry for the C drive should already be there so you only need to add a folder for other drives.
BleachBit wipes the space using a single pass of blank data (zeros). The developer believes this is totally sufficient and additional passes do nothing but slow down the process. Both portable and installer versions are available.
10. Windows Cipher.exe and Raymonodcc Free Space Wiper Frontend
The Windows Cipher tool located in the System32 folder is actually a file encryption utility. It can also be used to wipe data from unused disk space. Simply open a Command Prompt or PowerShell window and type the command below followed by the drive letter.
Cipher uses three passes to overwrite the specified drive’s free space. It starts with zeros, then the opposite (FF’s), and finally random data (similar to DOD 5220.22-M). The advantage of using the Cipher tool is the availability in the Windows operating system since Windows 2000 plus you can run it from a Command Prompt without elevation.
Raymonodcc Free Space Wiper Frontend
Although the first tab of our Free Space Wiper Frontend tool is for SDelete, the other tab is for this Cipher tool. Because Cipher is already in Windows you don’t need to download anything else.
All you have to do is run the tool and go to the Cipher tab, select which drive’s free space you want to clean from the drop down and press the run button. The Cipher command will open in a console window and perform the three passes free space erase.
Final Note: Talking about the most effective way to wipe drive data always sparks debate online. However, even Peter Gutmann, the man associated with the famous 35 pass method has said a few passes of random scrubbing is the best you can do on modern drives. Other companies like Bleachbit also say similar things in that you don’t need several passes for the wipe to be effective and it’s mostly just a waste of time.
Therefore, we’d recommend the three pass DOD 5220.22-M as the absolute most any normal user will require and you really don’t need to go above that. Even a single pass of random data should be enough in most cases.