These instructions work for any version of Windows, any browser and any make of anti-virus software. There is no need for any special preparation, although it is worth checking that any anti-malware programs are installed and running. To begin, visit the official European Institute for Computer Antivirus Research (Eicar) website and click the ‘Download anti malware testfile’ button at the top right. Now scroll to the bottom of the page and, in the area labelled ‘Download the standard protocol http’, there are links to four files, each starting with ‘eicar’. These are simply different versions of the same test file, used for testing how a virus scanner deals with compressed (zipped) files or those pretending to be a text file.
Click on the link labelled ‘eicar.com’. Depending on the browser and anti-virus software, the download may be immediately blocked, which is a good result. Accept the program’s default actions (choose ‘remove’, ‘clean’ or ‘quarantine’, rather than ‘repair’ if asked), and try again on the other file links. In Internet Explorer 8 and 9, the built-in Smartscreen Filter will also block the download, showing a warning box (in IE8) or warning bar (in IE9) in the browser window. Other browsers may allow the download, but the anti-virus tools should prevent it from saving to the hard disk if they are correctly configured.
If any files were successfully downloaded, try double-clicking each one to see if this triggers the anti-virus software. If not, the anti-virus software may not be working, and this should be investigated further – either check the settings, reinstall the program or try a different one (the free Microsoft Security Essentials is a good choice). The test files themselves are completely harmless (they just contain plain text), and can be deleted permanently by opening the folder they were downloaded to, selecting them and pressing the Shift key and the Delete key together.