Symantec Corp has announced the publication of its April 2010 MessageLabs Intelligence Report.
Analysis reveals that Rustock has surpassed Cutwail as the biggest botnet both in terms of the amount of spam it sends and the amount of active bots under its control. While Rustock has reduced the output of individual bots by 65 percent, it has increased the number of active bots by 300 percent, making up for the decreased output. Meanwhile, Cutwail has reduced in size to 600,000 bots down from 2 million bots in May 2009 and is now responsible for only 4 percent of all spam. Rustock remains the largest spam-sending botnet responsible for 32.8 percent of all spam.
“Affected by the closure of ISP Real Host in August 2009, Cutwail likely lost the ability to update some of its bots causing its numbers to diminish greatly without the ability to recover,” said MessageLabs Intelligence Senior Analyst, Paul Wood. “As a result, Rustock has taken over significant volumes from spammers by undercutting the market with greater capacity and lower operational costs.”
Other report highlights:
Spam: In April 2010, the global ratio of spam in email traffic from new and previously unknown bad sources was 89.9 percent (1 in 1.11 emails), a decrease of 0.8 percentage points since March.
Viruses: The global ratio of email-borne viruses in email traffic from new and previously unknown bad sources was one in 340.7 emails (0.294 percent) in April, an increase of 0.01 percentage points since March. In April 28.9 percent of email-borne malware contained links to malicious websites, an increase of 12.1 percentage points since March.
Phishing: In April, phishing activity was 1 in 455.2 emails (0.219 percent) an increase of 0.03 percentage points since March. When judged as a proportion of all email-borne threats such as viruses and Trojans, the proportion of phishing emails had increased by 5.7 percentage points to 70.3 percent of all email-borne threats.
Web security: Analysis of web security activity shows that 10.9 percent of all web-based malware intercepted was new in April, a decrease of 4.0 percentage points since March. MessageLabs Intelligence also identified an average of 1,675 new websites per day harboring malware and other potentially unwanted programs such as spyware and adware, a decrease of 12.7 percent since March.