We use cookies to provide you with a better experience. If you continue to use this site, we'll assume you're happy with this. Alternatively, click here to find out how to manage these cookies

hide cookie message
80,108 News Articles

Botnet PCs send 25k spam emails per hour

That's 600k per day, or 4.2m per week

Security researchers have warned that bot-infected PCs can send as many as 25,000 spam messages each per hour,and 600,000 per day.

Email security firm Marshal8e6 deliberately infected machines in the lab of its research arm, TRACElabs, with the malware responsible for the world's nine biggest spam botnets, then observed the PCs' behaviour, including each bot's top-end spam capacity.

"One of the our objectives over the past few years has been to emphasise the dominant role that a handful of key botnets play in the spam we see today," said Phil Hay, a senior threat analyst with TRACElabs.

TRACElabs concluded that Rustock and Xarvester, the latter perhaps linked to the down-and-out Srizbi botnet, are the most efficient spam-spewers of the nine bots. Each is capable of sending up to 25,000 messages per hour, or 600,000 per day, and 4.2 million per week.

The next-most effective spam bot, said TRACElabs, is Mega-D, one of the bots that took advantage of the November 2008 takedown of McColo, a hosting company that harbored the command-and-control servers for several big botnets, including Srizbi and Rustock.

When McColo's connection to the internet was severed by its upstream providers - in large part because of investigative work done by security researchers such as Joe Stewart, director of SecureWorks' counterthreat unit - spam volumes plunged as botnet controllers couldn't tell hijacked PCs what to do. Since then, however, spam has essentially returned to pre-McColo levels as a bot master resuscitated damaged botnets or unaffected botnets picked up new spamming customers, and thus the slack.

Some well-known names rated relatively low on TRACElabs' list. Waledac, which analysts have said is a successor to 2007-08's Storm bot, was recently in the news when it was installed by PCs infected with the Conficker worm. The botnet can cough up 7,000 messages an hour, or 168,000 a day.

According to TRACElabs, Rustock bots were responsible for 26% of the spam generated in the first quarter of 2009, with Mega-D and Pushdo not far behind at 22% and 18%, respectively. The other efficient bot - Xarvester - held fourth place, accounting for just 8% of all spam.

Today's revelations aren't the first to note that some botnets are far more efficient at spamming than others. In a botnet census he conducted a year ago this month, SecureWorks' Stewart said that Srizbi - later the biggest loser in the McColo takedown - was capable of delivering 60 billion spam messages per day.

See more:

PC security advice


IDG UK Sites

Windows 9 release date, price, features: Microsoft teases new OS ahead of 30 September unveiling

IDG UK Sites

From the iPhone 6 to the iWatch and a new Apple TV we look at the products Apple is set to launch...

IDG UK Sites

September 2014 creative trends: 5 things you must see

IDG UK Sites

What to expect from Apple in autumn/winter 2014: iPhone 6, iPhone Air, iWatch, iPad 6, new Apple...