Experts warn of 'aggressive' rise in child-porn spam

Most of the email samples clearly suggest that the content will be offensive with explicit subject lines. The email message invites the recipient to click on a link to view illegal material.

To get through email filters that might look for specific text patterns, the author of these spam messages appears to have used extracts from a quotation database, selected at random. Other tricks used to slip through the spam traps include using asterisks between letters in the email subject headings.

"Seeing such offensive emails in our spam traps is always upsetting because no one should need to deal with such unpleasant material," said Carole Theriault, senior security consultant at Sophos. "It is too early to say whether this is a new trend, but this week has shown definite growth in the number of child-porn websites being linked to from spam messages."

Sophos said it had been passing details of the illegal and offensive material to the Internet Watch Foundation (IWF), the authorized U.K. organization that combats illegal internet content.

News of these spam campaigns coincided with 18 of the world's most prominent financial institutions and internet firms joining the International Centre for Missing & Exploited Children, which aims to eradicate commercial child pornography by 2008.