Spam botnets tighten stranglehold on UK PCs

Many unwanted messages are now malicious

The UK jumped into the top four spam sending countries globally in August as volumes of spam sent from infected PCs in the region almost doubled, according to the latest report from Symantec Hosted Services.

The firm’s monthly MessageLabs Intelligence report found that in August, the UK was responsible for 4.5 per cent of the world’s spam, more than double the percentage in April, with UK PCs appearing more frequently in prolific spam botnets such as Rustock.

Despite the number of bots under its control shrinking from over two million in April to 1.3 million this month, Rustock has actually doubled the amount of spam sent from each bot per minute, resulting in a six per cent increase in spam emails per day.

Eight per cent of Rustock’s bots were located in the UK in August, partially explaining the UK’s growth as a source of spam, according to Symantec Hosted Services senior analyst Paul Wood.

He added that other botnets with a significant presence in the UK, including Storm and Asprox, have also increased their output in August.

Wood said that there is still no clear answer as to why UK PCs are becoming more prone to infection.

“Maybe there is a degree of complacency about the type of security people have on their computers,” he added. “When you see the levels of sophistication out there it’s harder to keep up to date and detect the attacks early on unless you have sophisticated security.”

Wood pointed to the rise in web-based threats including legitimate web sites infected with drive-by-malware, as well as social network related threats, as having significantly increased the risk exposure of many UK PC users.

Spam is more than just a minor inconvenience to businesses. Aside from the burden it places on corporate email systems, many spam messages now come bundled with malware, as a new blog post from Symantec outlines.