Security software vendor Symantec has released its January 2011 MessageLabs Intelligence Report, revealing that the Bagle botnet has replaced Rustock as the largest spam sending network.
The company said that Bagel's rise follows the two week long decline in global spam levels over the Christmas period, when the three largest spam sending botnets, Rustock, Lethic and Xarvester halted their malicious activities.
The report informs that during this two week period, spam volumes were reduced by 58 per cent from 80.2 billion spam emails per day to 33.5 billion spam emails each day.
Rustock is now responsible for sending only 17 per cent of the spam emails - down from 47.5 per cent before - while Bagle has grown to become the biggest botnet, sending 20 per cent of all spam emails.
MessageLabs Intelligence Senior Analyst, Paul Wood, said in a statement: “At various points during Rustock's history, the botnet has often exhibited irregular spamming patterns by sending huge volumes of spam before going quiet for several weeks at a time.”