The takedown of the Rustock botnet has measurably reduced the amount of spam e-mail, according to an IBM Internet Security Systems report.
IBM said it has observed a sustained drop off of between 35% and 40% in global spam levels almost a week after law enforcement in the U.S. and abroad, along with attorneys from Microsoft, seized servers used as the command and control infrastructure for the botnet.
In early March the U.S. was the second most common source of spam on the Web, now, in the wake of Rustock, the U.S. ranks 15th. That is due to Rustock’s heavy reliance on U.S. based servers.
Rustock’s demise resulted in declines in U.S., Israel, and the U.K. most dramatically with 74, 66, and 54 percent declines in spam observed in those countries respectively, IBM reported. On the other side of the spectrum, Vietnam and South Korea were least affected with two percent drops in spam volume each.
IBM said that the declines aren’t unprecedented in the spam industry and are only about half of what they were when the spamming industry went on holiday at the beginning of the year. Global spam levels may well return to the levels seen before the Rustock takedown over time.
In the meantime, there are some great comparative charts and spam-level graphs on IBM’s Internet Security Systems blog.