Rustock botnet largely responsible for worldwide spam

August 25, 2010 3:06 PM EDT

Of all spams, those sent from botnets increased to 95 percent in August from 84 percent in April, said a report from Symantec MessageLabs Intelligence. Occupying 41 percent of the total spams, Rustock is mostly responsible for the botnet spam, it said.

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“One exception is Rustock which has decreased its number of bots but increased its volume, more than doubling the amount of spam sent from each bot per minute resulting in a 6 percent increase in spam emails per day,” said Paul Wood, senior analyst, Symantec MessageLabs Intelligence.

By ditching the usage of Transport Layer Security (TLS) to send spam, Rustock has speed up connections that resulted in increased throughput from it, the report said.

“As a result, Rustock’s dominance has never looked better as its spam-per-bot-per-minute rate more than doubled from 96 spam emails to 192,” said Wood.

However, US remained home to the greatest number of bots, most importantly Rustock, Storm and Asprox. Rustock bots in the US increased from 7 percent in April to 14 percent in August.

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The report also finds doubling of spam generated from UK with 4.5 percent of the world’s spam in August. UK stands at fourth place in most frequent sources of spam behind the US, India and Brazil.

Highlights of the report for August:

-- the global ratio of spam in email traffic in August was 92.2 percent (1 in 1.08 emails), up by 3.3 percentage points from July.

-- the global ratio of email-borne viruses in email traffic was 1 in 327.6 emails (0.31 percent) in August, down by 0.02 percentage points from July.

-- phishing activity was 1 in 363.1 emails (0.275 percent), up 0.10 percentage points from July.

-- spam levels in Hungary increased to 96.3 percent in August making it the most spammed country. In the US, 92.5 percent of email was spam and 91.7 percent in Canada.

-- virus activity in Spain was 1 in 64.1 emails, making it the most targeted for email-borne malware in August. Virus levels for the US were 1 in 417.9 and 1 in 290.8 for Canada.

-- Oman became the most targeted for phishing attacks in August.

-- Automotive sector was the most spammed industry sector with a spam rate of 94.8 percent.

-- regarding malware, the Government/Public Sector became the most targeted industry with 1 in 74.6 emails being blocked as malicious.

This article is copyrighted by International Business Times, the business news leader