Facebook rolls out face recognition by stealth

UPDATE, 14:00GMT, 8/6/11: Facebook has responded to criticism of its face recognition technology with a statement. Read the full story here.

Millions of Facebook users could find their personal security at risk, after the social network quietly rolled out facial recognition technology that can identify users' faces from images posted on the site, security vendor Sophos has warned.

Back in April, Sophos warned of Facebook's indifference towards users' privacy, claiming that a "conspiracy of silence" had met an open letter sent by Sophos, complaining about the company's policy of outing user data by default, and putting the onus on individuals to police their own privacy. Now that policy has been extended to the billions of images uploaded to the site.

Facebook's facial recognition isn't new - the company first introduced the technology last year to users in North America, enabling then to automatically recognise and tag faces in photographs uploaded to the site.

But in the last few days, the site has covertly deployed the feature on millions of user accounts around the world, without giving them any notice - and, says Sophos technical consultant Graham Cluley in a blog post, users would be well advised to check their privacy settings and disable the feature if they're concerned about security.

Unless you disable the feature, each time one of your Facebook friends uploads a photograph, Facebook will try to determine if the picture looks like you. If it makes a positive ID, your friend will be urged to tag you.

While it's true that no images will be tagged unless your friends choose to do so, it's another erosion of privacy to find the social networking site actively persuading them to do so - and giving you no notice that you've been tagged.

To disable this feature, use the following simple steps:

1. Select Privacy Settings from the account menu at the top right of the screen.

2. Click 'Customise settings'.

3. Under 'Things others share', you'll see an option entitled 'Suggest photos of me to friends'. Click the 'Edit settings' button next to this.

4. By default, Facebook enables facial recognition for all adult users - to alter this, change the drop-down option in the dialogue box to 'Disabled', and click OK.