Spam trojans a growing problem for ISPs

Analysis: most spam now originating from residential broadband networks – worms, spam trojans to blame
Spam traffic created and routed by spam “trojans” is clogging ISP mail servers, forcing unplanned network upgrades and stoking antagonism between large and small ISPs, according to an analysis by Sandvine Incorporated. Spam trojans are likely responsible for up to 80% of all spam.
What used to be merely a nuisance is becoming a major headache for service providers of all sizes. Contrary to the seedy stereotype of lone spammers looking to “get rich quick,” feverishly toiling away in dark basements, the vast majority of spam now emanates from home computers infected with spam trojans. Typically installed surreptitiously by worms or spyware, spam trojans exploit vulnerabilities created by worms to bypass normal email routing and drop spam messages directly into end user machines. In fact, many of the most well-publicized worm attacks in recent months were launched expressly to install spam trojans on unsuspecting end users’ machines – waiting to be utilized at a later date as a spam delivery relay.
Studies have shown that spam trojans now account for the vast majority of today’s spam. The unique behaviour of spam trojans on the network taxes ISP infrastructure and, in the case of smaller ISPs, creates perceptions that some networks are generating more than their fair share of spam and other types of malicious traffic.
“Subscribers’ in-boxes are bombarded daily, and while spam filters can provide an effective treatment, the scale & scope of the spam problem means additional remedies are needed”, said Marc Morin, co-founder and chief technology officer of Sandvine Incorporated, “As a complement to existing mail server and client based tools, service providers need to arm themselves with network-based anti-spam defenses.”
For more information, download Sandvine’s trend analysis “The Effects of Spam Trojans on Service Provider Networks” (