May witnessed an all-time low for virus-laden emails and a record high for spam, according to stats from email filtering firm BlackSpider Technologies. Emails containing malware made up just 0.73 percent of all emails scanned by BlackSpider last month while junk emails represented 87.74 per cent. By comparison, the number of virus-infected emails reached 3.93 per cent of all emails in December 2005, a record high. The drop since then is reckoned to be down to a shift of tactics by malware authors, who are beginning to favour targeted attacks.
The high level of spam last month is partly explained by a spike that occurred between 21 and 23 May, when UK businesses were flooded by more than 250m spam emails. The surge of spam were sent from a botnet of more than 150,000 compromised PCs, or 'spambots'. The content of the emails varied throughout the deluge. Each one, however, links to websites selling penis pills and other drugs. The subject lines and body text of each spam email contained obfuscated drugs names (such as CtqALLlS). The emails ended with a poem or paragraph of random obfuscating words designed to fox less sophisticated email filters.
James Kay, CTO, BlackSpider Technologies, said: "The sheer number of compromised machines making up these botnets demonstrates that, despite the reduction in the percentage of email carrying viruses, virus infection continues to be a widespread problem". ®