Bunch of fives: Memorable security blunders

Sometimes its difficult to know who can be trusted when it comes to computer security. While the Government, big websites and security software vendors do their best to stop your PC becoming infected by malware or your data falling into wrong hands, mistakes do happen and sometimes the results are priceless. Here are five memorable blunders where the only possible response was issuing an apology, whilst eating a giant slice of humble pie.

1. McAfee
You purchase security software so your computer is reliable and free from malware. You do not expect the opposite, that it cripples your PC and makes it unusable. But that is exactly what McAfee's recent update to its security software has done, as it incorrectly identified a critical system file as a virus, which prevents Windows from starting.

2. Symantec
In January this year, a definition update to Symantec Endpoint Protection and Norton Antivirus incorrectly identified the music-streaming software Spotify as a trojan, preventing users from listening to their favourite music.

Symantec responded quickly and released an update that fixed the application, although unfortunately there was no update to fix peoples' music collections so they no longer contained Cliff Richard or Rick Astley records.

3. AVG
While McAfee's rivals are no doubt sniggering about the company's recent misfortune, some cannot pass judgement, as they are guilty of the exact same thing. Step forward AVG, a security company that, in 2008, identified a legitimate Windows system file as a trojan horse, causing the PC to reboot endlessly.

4. Facebook
In 2008, the Facebook website was testing a redesign for its members, so that after logging in they would no longer be able to find their photos, friends list or profile, until they became used to the new layout.

As well as confusing its users though, this particular update resulted in the personal details of approximately 80 million users being revealed to the rest of the world, ripe for the plucking by identity thieves.

5. Missing UK child benefit databases
In 2007 the UK government lost a pair of CD-Rs that contained details of every family that claimed child benefit in the UK, which was thought to be 25 million people. While the discs were password protected, a weak form of encryption was used which would do nothing to dissuade a determined hacker.