One of the Internet's most notorious malware and software exploit hubs, the Russian Business Network (RBN), has suddenly gone offline.

Trend Micro reports that Internet domains associated with the network went down at 7 p.m. Pacific Standard Time on Tuesday, Nov. 6 (3 a.m. GMT Wednesday, Nov. 7), taking with it a network provider accused of hosting some of the worst criminal activities the Internet has to offer, including various high-profile software exploits, voracious Trojan malware, and even hosting sites used for child porn.

"That RBN, currently, has no Internet connectivity means that the Web is a somewhat safer place today. Unfortunately, this may not be for long. RBN may find new upstream providers," suggests the Trend blog.

It is not clear precisely what has caused the downing of the RBN, but Trend speculates that some problem with an upstream ISP might be to blame.

The Washington Post times the downing as having happened on Nov. 4, and states that the RBN has been in trouble since the newspaper publicized its activities in October causing upstream providers Tiscali.uk and the Russia's C41 to drop it.

The RBN is significant enough to have spawned numerous articles detailing its activities, an extensive entry on Wikipedia, and a number of sites dedicated to documenting its alleged nastiness. Recent malware events it has been blamed for include October's Adobe PDF exploit, and the hacking of the Bank of India in September.

One RBN watch-blog claims it was behind 40 of 57 fake antimalware software products came from it.