Rustock was the prevalent spam-sending botnet responsible for the majority of botnet spam
The percentage of spam sent from botnets has increased to 95% of all spam, an increase of 11% compared to 84% in April 2010, according to a report from Symantec.
The report, August 2010 MessageLabs Intelligence Report, revealed that Rustock was the prevalent spam-sending botnet responsible for the majority of botnet spam, up 41% in August compared to 32% in April.
However, the number of bots under its control decreased to 1.3 million in August from 2.5 million in April, the report added.
The analysis also revealed that increased throughput from Rustock is that the botnet has stopped using TLS encryption to send spam, resulting in increased speed in connections.
In March, TLS encrypted spam accounted for 30% of spam from all sources and approximately 70% of spam from Rustock.
The report said that the US topped in number of bots, notably Rustock, Storm and Asprox, with Rustock bots increasing to 14% in August compared to 7% in April.
UK was in fourth position by doubling its share of world’s spam by 4.5%, followed by Germany, France and Italy. Four of the top 10 spam countries are found in Western Europe, the report said.
The global ratio of email-borne viruses in email traffic from new and previously unknown bad sources was one in 327.6 emails (0.31%) in August, a decrease of 0.02 percentage points since July.
In August, 21.2% of email-borne malware contained links to malicious websites, an increase of 4.1 percentage points since July.
MessageLabs Intelligence also revealed that web security activity showed 34.3% of malicious domains blocked were new in August, an increase of 3.8 percentage points since July.
Additionally, 12.9% of all web-based malware blocked was new in August; a decrease of 0.2 percentage points since last month.
According to the report, spam levels in Hungary rose to 3.3 percentage points to 96.3% in August, followed by US (92.5%), Canada (91.7%), the UK (91.9%), Netherlands (93.5%), Germany (93%), Denmark (94.9%), Australia (91.7%), Hong Kong (93.2%), 7.8%), Singapore (90.3%), and Japan (90.3%), and China (94.1%).
The report further said that virus activity in Spain was 1 in 64.1 emails, making it the most targeted for email-borne malware in August.
While virus levels for the US was 1 in 417.9, Canada was 1 in 290.8, Germany was 1 in 281.3, Denmark was 1 in 354.9, Netherlands was 1 in 461.6, Australia was 1 in 346.3, Hong Kong was 1 in 264.9, Japan was 1 in 493.8 and Singapore was 1 in 634.6.
Oman became the most targeted for phishing attacks in August with 1 in 185.3 emails comprising a phishing attack.
The most hit industry by spam mails was the automotive sector with a spam rate of 94.8%, followed by education sector (92.9%), chemical & pharmaceutical sector (92.6%), IT Services (92.7%), retail (92.8%), public sector (91.7%) and finance (91.2%), the report added.
MessageLabs Intelligence pointed out the Government/public sector as the most targeted industry for malware, while virus levels were highest in the chemical & pharmaceutical sector, followed by IT services, retail, education sector and finance.