A British Web site that warns consumers about online financial scams was taken down by a distributed denial-of-service attack on Monday.
Bobbear was being overwhelmed by a "huge" botnet with "over half a million recorded zombie hits from midnight to 8 a.m. today (GMT)," Bob Harrison, administrator of Bobbear, told security firm Sophos.
The site remained down as late as midday Pacific time.
Bobbear has been targeted before. In October 2007, hackers attempted to damage the company's reputation by sending e-mails that solicited donations to the company via an online payment service.
"An attack like this is unfortunate news for the Internet community, as it disrupts the dissemination of hundreds of pages of warnings about e-mail frauds archived by Bob over the years," Sophos senior technology consultant Graham Cluley writes in his blog. "The only consolation that Bobbear can take is that they must be having an impact on the fraudsters if they are prepared to launch an attack like this."