Spammers using domain parking services to bypass anti-spam filters

Security experts are warning that spammers are increasingly taking advantage of domain parking services offered by registrars in an attempt to circumvent reputation-based anti-spam products and conceal their sites.

Symantec.cloud's senior software engineer Nick Johnston explained in a blog post that the parking services are usually used by registrants to reserve a domain for future use in order to mitigate the risk of cyber squatting or to monetise a particular domain through online advertising.

However, Johnston's team recently noticed "a large domain parking service being abused by spammers on a massive scale".

"Each domain hosted on the service contains an open redirect script, allowing spammers to redirect to any URL of their choice," he said.

"Since the redirect does not affect the parking page, and domains parked on domain parking services are typically not used for any other purpose, it is unlikely that the domain owners will notice when their domains are inevitably added to anti-spam block lists."

Johnston warned that such strategies could help spammers escape detection by some anti-spam products, especially given that many of the domains have been registered for years "and are therefore seen as more likely to have a good reputation".

Despite the shutdown of the notorious Rustock botnet earlier this year, spam continues to blight every inbox around the world.

Symantec's MessageLabs Intelligence Report for May 2011 found that abuse of URL shortening services led to a 2.9 per cent increase in spam during the period.