How do they get in?

Viruses are usually attached to executable files. This means that, although they may already be in your computer system, they’re not activated and can’t spread until you open the host program or file.

Viruses can be camouflaged as images, attachments, or video and audio files you download, or be picked up when visiting a compromised website. Some viruses may exploit operating system vulnerabilities. The most common ways to pick up a virus are by downloading a file from the Internet and by clicking on attachments.

What devices can they infect?

Most commonly, viruses affect computers. Computer programs can be offered online for anyone to download without any review taking place, and therefore can pose a significant risk of infection by viruses – hence we see more viruses on computers than anywhere else.

However, other devices such as tablets and smartphones are vulnerable too. There are fewer viruses affecting phones and tablets because apps are reviewed before being put up on app marketplaces such as Google Play and Apple’s App Store. Also, apps are generally kept separate from the operating system and therefore can’t affect the entire device. But if you root or jailbreak your device, you expose it to malware.

Android, being open source and highly popular, is the preferred target for most mobile malware. iOS is less vulnerable because it’s a closed, ‘sandboxed’ system and also because Apple has a smaller market share than Android. But this doesn’t mean iOS is immune to attack – and both platforms face an equal risk from social engineering.

How can you protect against viruses?

Being aware of the threats and acting accordingly will lessen the risk of your computer or smart device picking up a virus. One of the best ways to protect against infection is to install comprehensive Internet security software across your devices, and keep it up to date. Make sure your computer firewall is turned on, and run regular scans. Also:

• Keep your operating system software up to date.
• Adjust the security settings in your web browser.
• Beware of fake virus alerts.
• Surf safely. Don’t open unsolicited email or message attachments or click on suspicious links. Instead, use bookmarks or type the web address straight into your browser.
• For everyday computing, use a standard user account. Only use administrator accounts when you really need to.
• Be aware that free music and video file-sharing programs may be packaged with other, unwanted software that compromises your privacy and security.
• Always read privacy policies and End User Licence Agreements before downloading any software.
• Don’t jailbreak your device.
• Read app reviews and check the permission that apps request. Always download apps from official app stores.

Remember to back up regularly so that you can restore your data if you need to.

What should you do if your computer is infected?

Run a scan. Your Internet security software might be able to identify and manage any threats that may have slipped through its defences. Follow any steps the program advises to deal with the threat.

If you intend to troubleshoot, don’t do it on your infected computer.

Attempt to remove a virus manually only if you’re sure you know what you’re doing and you’ve backed up all your important data first. If in doubt, consult a professional.

If you think the infection may be serious, turn off the WiFi or unplug your computer. This will stop the virus from spreading to other devices in your network, and prevent it from sending or receiving information. Then book it in with the computer doc.

Keep up those defences

These little bits of malicious software can cause a whole lot of irritation and disruption – and do a great deal more damage if files are corrupted or deleted, or your confidential details are stolen. And if a virus isn’t stopped, it can replicate and spread itself, doing harm to others.

The best way to deal with viruses is to avoid getting them in the first place. Now you know what they are and how they invade, you can act accordingly and do your best to keep them out.