Does your smartphone or tablet have an anti-virus program installed? It's a common misconception that anti-virus software should only be installed on laptops or PCs. That's incorrect: all your devices should have some form of virus protection.

Why should you install an anti-virus program?

Windows and Mac OS X computers are attacked most frequently because they are so widespread. At the moment there is hardly any known malware used to 'commercially' target Linux operating systems. So, although it is not absolutely essential to have a protection program installed on your computer if it is solely for private use, it is still recommended to prevent you passing on dangerous files to others inadvertently.

Anti-virus software checks new files (for example, e-mail attachments) and the computer as a whole for any malware. To do this, it mainly compares the data on the computer with the 'fingerprints' of known malicious programs. However, these 'signatures' always need to be up to date, as new versions of malware appear every single day. This means you must update the software regularly.

You can either do this using your program's automatic update function or by downloading the updates direct from the manufacturer's page. There are also other techniques designed to detect previously unknown malware. However, these 'heuristic' methods do not have very good detection rates; this is a trade-off to ensure they do not produce too many false alarms.

In the past, users had to open their virus protection program at regular intervals, then the entire hard disk, specific drives, floppy disks or CD-ROMs would be scanned. It is much easier nowadays. If the auto-protect function is enabled, the program automatically scans your computer in the background every time the system starts up. You can recognise this by the icon on the taskbar. If a virus is found or the scanner detects anything suspicious, you will see a notification in a message window.

Paid-for or free of charge?

Some manufacturers of protection software, as well as Microsoft, offer free versions of their programs alongside the paid-for versions. The free software often comes with less functionality than its commercial counterpart, so it is always worth comparing the features carefully. Many computer magazines put common protection programs to the test on a regular basis and clearly explain how well they work, how easy they are to use and what functions they offer.

Online virus scanners

Some private users see online virus scanners as an alternative to conventional anti-virus programs. And at first glance, it seems logical. Since the virus scanner runs on the Internet directly, it saves the trouble of installing an extensive anti-virus program. Nor does the user have to keep on updating the virus signatures, as the latest updates are always made available online. But, since convenience isn't everything, this is not enough to justify replacing a comprehensive anti-virus package.

If you rely solely on an online scanner to protect your PC, you will lose out on the background monitoring function. This is a feature in conventional anti-virus programs that scans every file used on your computer. To achieve a similar effect with an online virus scanner, you would need to scan your computer or the new files being used on it constantly. And then you have negated the benefit of not having to worry about the latest virus signatures.

But that's not all. There are two other disadvantages of online virus scanners:

• They require you to have enabled ActiveX. Generally speaking, you should avoid ActiveX in your browser wherever possible, as it contains no protective mechanisms at all.
• If you have a clear suspicion that your PC is already infected, you should avoid using the Internet as far as possible. This is because the malware will spread even further over any online connection. And if you have been infected by a dialler, in the worst-case scenario you could be connecting to the Internet via an expensive phone number.

But could an online virus scanner be of any use to you, despite all these drawbacks? Yes, if your computer is as-yet unprotected and you suspect it has a virus, an online scanner can help you to track it down. By this point though, the virus may already have caused irreparable damage. So once you have removed this malware, you should then install a conventional anti-virus program to protect you in future. The top priority is to always keep the virus signatures up to date.

A popular scam: Spreading bogus anti-virus software

Cyber criminals often attempt to trick users into installing bogus anti-virus software. It works something like this: as you are surfing the Internet, you see a supposed warning that your computer is infected with malware. These warnings appear in a separate browser window and look very much like those issued by reputable anti-virus programs. In order to remove this seemingly severe infection from your PC, you are prompted to download a virus protection program.

Once you have installed this apparent anti-virus solution, you are then prompted to buy the program or a licence for it. If you refuse to do this, bogus virus warnings will keep on appearing at regular intervals, together with a request for payment.

But the programs offered in such scams often have no function whatsoever. They are simply a way of getting users to make a purchase and getting hold of their credit card details. Sometimes a PC will be infected with malware when the user downloads the 'protection program', so it can then be added to a botnet, for example.

Visit the heise.de website to see what such fake virus warnings and anti-virus programs look like.

Which virus protection program is recommended?

Always be sceptical of unsolicited offers of software and only ever buy anti-virus software from reputable providers. The selection of a suitable virus protection program for Windows-based systems is of particular importance.

For private users, it is worth considering both free and paid-for versions of anti-virus software to guarantee adequate protection of the system against computer viruses and other malware. Paid-for versions may have more functions. But provided that the useful additional features found in paid-for solutions, such as

• parental control filters
• monitoring of browser and email activities for malware, as well as
• advanced, behaviour-based detection of malware

are not required, free virus protection programs will be sufficient. This includes, for example:

• Avira Free Antivirus
• avast! Free Antivirus
• AVG Anti-Virus Free

These virus protection programs all offer user interfaces in both English and German. They are easy to integrate into the Windows operating system, use automatic updates and have a good detection rate. The manufacturer of the operating system itself also offers a free virus protection program in the form of Windows Defender.