What is a Computer Cleaner?

In the course of using a computer, various records accumulate that reveal a user’s activities on and offline. A subsequent party can access these records to snoop on the previous user’s actions, and might even be able to gain personal information. A computer cleaner is a utility that wipes these records to maintain privacy.

The number and type of records generated while using a computer are numerous and varied, found in many different places throughout the computer. For example, many software programs keep a list of recently opened files and documents, or recently viewed images or movies. Run and Find histories are also logged. Temporary files archive copies of documents that might persist for months or even years, if not wiped.

Online activities also leave footprints. A Web browser sets aside allocated memory on the hard disk as cache, or a place it can keep copies of recently viewed Web pages so that these pages can load faster on subsequent visits. Browser cache is a rich source of information about previous browsing sessions.

The convenient auto-complete or auto-fill feature scans records of previously typed words to predict input based on the first few keystrokes entered. This feature can inadvertently reveal previous searches and websites visited, even if browser cache has been wiped. A public computer might “leak” personal information such as name and address, if a previous user filled out a form providing this information.

Snoops cannot read computer cookies because the contents are encrypted, but they can see which websites issued the cookies, inadvertently revealing surfing habits to any would-be busy-body. A computer cleaner takes care of this by wiping cookies.

Windows Internet Explorer makes use of a file called index.dat, which stores information about websites visited and keeps an index of cookies received. Even if using the built-in privacy features of the browser to wipe history, cookies and cache, the index.dat file will remain intact. Only a comprehensive computer cleaner will wipe the index.dat file. Explorer creates a new, ‘blank’ one at the next session.

A good computer cleaner will address all of these issues and more, and should be easily configurable to optionally preserve certain files such as useful cookies. Running the utility from a USB memory stick or flash drive will allow you to clean footprints from a public computer or work station without installing the software.

Although a computer cleaner does a good job of protecting privacy at a basic level, it is not a forensic tool. Windows operating systems lock a portion of the hard disk to use as a designated paging or swap file, for example. This file contains a great amount of unorganized (and therefore seemingly chaotic) data that nevertheless provides records of usage. Readily available tools allow anyone to view the contents.

You can set Windows or a computer cleaner to wipe the paging file at shutdown, but this action typically delays the shutdown process by several minutes or longer. Also, shutting down a public or work computer might not be practical. More obscure traces of activities left untouched by a computer cleaner might also persist that would not likely be found by the casual snoop, but could be recovered by law enforcement or administrators.