Tech Features

Unwanted e-mail: Picture spam is taking over inboxes

By Michael Thieroff Sep 3, 2006, 4:18 GMT

Magdeburg, Germany ­ Unwanted e-mail is nothing new. Nor are anti-spam programs to keep out the unsolicited correspondence. But new image spam is changing a lot of the old rules.

Andreas Marx, of the anti-virus software laboratory AV-Test in Magdeburg, Germany, has noticed the growing flood of photo spam. 'About a third of spam today is image-based,' he says.

'In this form of spam, text is included in the image and then sent on. Most spam filters are designed to analyze text,' says Marx. 'But they are powerless when it comes to images.'

Olaf Pursche, a security expert for the Hamburg-based magazine 'Computerbild' (Computer Image), has also noticed the jump in spam. 'Many spam filters still can't screen out image spam. That means more unwanted mail in peoples mailboxes.'

The spam filters are thrown off by the variety of the e-mails. 'The pictures are generated so that every e-mail sent is slightly different,' says Marx. This is achieved by changing the size or formatting of a picture. Even a few altered pixels can let an e-mail sidestep a filter.

Sascha Strauss, an anti-spam strategy adviser for the German Federal Office for Information Technology (BSI) in Bonn, advises users who don't want their pictures of birthday parties or weddings to land in their recipient's spam folder to behave differently than spammers. 'An e-mail without text and just a GIF picture file usually means spam.'

But the recipient can also take precautions. Spam filters should be set up so that mail sorted into spam folders is not immediately deleted. Users should periodically look through that file and delete unwanted e-mails. 'Before you open the spam folder to look at these e-mails, you should make sure your virus protection software is updated,' advises Strauss.

People who use e-mail services can live without spam filtering software. 'Our tests show that purchasing filtering software is usually not worth it. The best program was only ranked satisfactory,' said Pursche of 'Computerbild.' Filters employed by online e-mail services work much better.

E-mail services and providers are interested in stopping the flow of spam. 'Spam makes significant attacks on information technology security. Targeted mass mailing operations endanger the usefulness of the Internet and services from companies and offices,' says Strauss. Just the transmission and saving of unwanted e-mails costs providers a pretty penny.

There is no guaranteed protection from spam. But one can still do a lot to block its flow. Pursche advises: 'Every computer user should use an alias address for online forums or Internet gaming. That means creating a second e-mail account.' Real e-mail addresses ­ the ones divulged to friends and acquaintances - should only be revealed sparingly.