- Social Engineering. This is where a site pretends that a potentially dangerous file (whether that is an executable, video, document or something else) is safe and legitimate and gets the visitor to click or download it. Even entire sites can pretend to be something they are not.
- Vulnerabilities. Bugs in web browsers, plugins or other programs that open up content from the web can sometimes allow bad things to run on your computer. This includes files which you wouldn't normally associate with having executable content such as Adobe Acrobat (PDF) files, ActiveX applets and videos. Vulnerabilities in the past have allowed these nasty bits of code to live inside innocent looking files which then get run automatically by the web browser. This is another good reason to always keep your browsers, plugins and operating system up to date with updates and patches issued only by their creators.
- Third Party Interference. Sometimes web sites get hacked and the contents get changed. If it is a subtle change to files made available to download it can be some time before anyone notices. It isn't always the sites themselves either which are the culprit, there have been several cases in the past where the companies who provide adult banner adverts have allowed nasty code to slip through with the adverts that get embedded into other peoples web sites.
The 7th to 11th November 2011 is the annual Get Safe Online week to raise awareness of internet safety issues. We are proud friends of the campaign so if you want to know more, please click the badge below.