Sometimes spyware can be used legitimately. Mostly, though, it’s malicious, aiming to exploit personal information such as your credit card details, user names and passwords.

What does it do?

Spyware collects useful information for commercial benefit. This could include:

• Tracking your browsing habits and monitoring program use for marketing purposes.
• Redirecting you to advertising sites, and distasteful or compromised sites.
• Sending you unwanted and annoying pop-up ads.
• Collecting your valuable personal information and sending it on to fraudsters.

Spyware can gather lots of different sorts of information, from your game, social media and email account logins to sensitive financial and business credentials.

Spyware has been used to record instant messages and Skype chats, control webcams, take screenshots and even make changes to your hard drive.

Spyware can alter your settings – change your default home page or redirect your browser, for example, or install add-ons that you don’t want. Often it can be hard to undo these changes.

Running quietly in the background, spyware can also use up your computer’s resources, slowing it down or causing it to crash.

It’s not all bad, though. You might knowingly sign up for a ‘free’ online service in return for allowing the software to track you and send you ads. It’s up to you to determine whether the compromise is worth it.

Ask yourself: is this program a nuisance or, worse, an invasion of your privacy and security? If so, you need to take action.

How does it get on to my computer?

Often spyware is covertly downloaded along with software that you’ve chosen to install – such as a video or music file-sharing program. Typically it piggybacks on freeware. We tend to accept end-user agreements without reading the tedious small print – which is where notifications of user tracking and ad delivery tend to be placed.

You can also inadvertently pick up spyware while surfing the Internet. You might be persuaded to click on a pop-up window offering a prize, a free scan, or urging you to download essential software – but instead you’ll be opening the door to spyware.

Emails, instant messages and social media messages may all contain links to spyware. Spyware can also be picked up via drive-by download, where merely viewing a compromised email or website can trigger a spyware download.

How do I know if my computer is infected?

Spyware is designed to be hidden and can therefore be hard to detect. However, there are signs that could indicate spyware infection.

• Pop-up ads start appearing frequently.
• Your default home page has changed.
• Your computer starts to run slowly, freeze or crash.
• Your browser redirects to unsolicited sites.
• Your security software doesn’t run properly.

How can I avoid infection?

• There’s a lot you can do to protect your computer from unwelcome software. Prevention is the best defence but if your device is already infected, be sure to read our guide on how to remove spyware here.
• Make sure your security software includes protection against spyware. Run scans regularly.
• Be careful what you download. Ensure that you understand what the program will do. Weigh up the risks and benefits. Take particular care with free or file-sharing music and video programs.
• Read the fine print in licensing agreements before clicking, ‘I accept/agree’. Make sure you read the privacy statements too. Look out for reference to data-gathering and sharing information with third parties. It may be bothersome, but it’ll be a lot less of a nuisance than dealing with malicious spyware once it’s installed.
• Download only from known and trusted sources.
• Avoid clickable ads.
• Beware of ‘free’ anti-spyware tools.
• Surf carefully. Instead of clicking on links on dubious websites or in emails, use bookmarks/favourites or type the web address into your browser.
• Don’t make it a habit to sign in as an administrator. Administrators have unrestricted access to the computer and can make system-wide changes. If you inadvertently let in spyware while using an administrator account, you may give that spyware total access too.
• To close a pop-up window safely, click the x in the top right-hand corner of the window. If this doesn’t work, hit Alt + F4. Alternatively, use the Task Manager – although be aware that this method will close all running programs, so you might lose what you were working on along with the pop-up.

Keep the spies at bay

You can’t rid the Internet of spyware, but you can help protect yourself against it. Knowing what spyware is, what is does and how it gets into your machine helps you to take control and avoid accidentally downloading unwanted software.