A single botnet has grown so dramatically in the last two months that it now accounts for half of all the spam, according to new research from Marshal’s TRACE team. The Srizbi botnet has steadily increased its network since the beginning of 2008 and is now the world’s largest spam botnet.
“Srizbi is estimated to comprise at least 300,000 compromised computers and sends more than 60 billion spam messages per day. Recently, the botnet has been used to promote a range of products including watches, pens and male enlargement pills. Srizbi also actively distributes copies of its own malware in malicious spam campaigns using social engineering ploys to trick recipients into infecting their computers.
In January, Marshal announced findings that the infamous Storm botnet had lost its place as the number one source of spam to the Mega-D botnet; otherwise known as Ozdok. Marshal’s latest data shows that Srizbi’s rise to prominence in February coincided with the decline of the Mega-D botnet after its control servers were taken offline for 10 days.
Mega-D quickly bounced back and regularly jostles with the Rustock botnet for second place in Marshal’s spam statistics. Marshal’s TRACE researchers have observed individual computers infected with the Rustock malware sending as many as 25,000 spam messages an hour.
Marshal’s charts and statistics depicting botnet activity over time can be found on the TRACE Center: http://www.marshal.com/trace/spam_statistics.asp.