The man believed to be responsible for distributing the notorious Blackhole malware toolkit has been arrested in Russia, a source told Reuters today. The source, a former Russian police detective in contact with Russia's federal government, said that the man went by “Paunch” in hacking circles.

No other information was given, but a spokesman for Europol in the Hague told Reuters that the police agency “had been informed that a high-level suspected cyber-criminal” had been arrested in Russia.

Blackhole is a widely known exploit toolkit that makes “drive-by” attacks easier for hackers to execute. It allows criminals to inject malware onto PCs that either visit exploit sites or are redirected to exploit sites from compromised websites. As one of the primary names behind Blackhole, Paunch kept the toolkit current as new weaknesses in commonly used programs were discovered: in 2012 Paunch released Blackhole 2.0, and recent custom versions of the toolkit incorporated ways to exploit vulnerabilities in Adobe Reader and Java's browser plugin.

Still, Sophos' Naked Security blog points out that in recent months, Blackhole's dubious popularity has waned due to competition from other similar exploit kits. While Blackhole accounted for 31 percent of the Web attacks detected by Sophos' security software in the second half of 2011, the company's data for August 2013 show a much more varied landscape, where Blackhole and another exploit kit called Cool (which is believed to be distributed by the same group) only make up four percent of the market.