The attack made Andale's site nearly inaccessible for auction sellers who use the company's services to manage their auctions and communicate with customers. The attack also turned off the company's popular auction counters and prevented the site from sending out end-of-auction notices to buyers and sellers.
Mountain View, Calif.-based Andale declined to publicly acknowledge the previous attacks in part because it was worried about "copycat" attacks, company chief executive Munjal Shah said.
"This has impacted our user base so much, that we have to let them know what is going on," he said.
Andale executives on Tuesday contacted the REACT task force in San Jose about the attacks. REACT, which stands for Rapid Enforcement Allied Computer Team, is comprised of local and federal authorities and investigates computer crimes. Chris Hsiung, a detective with the Mountain View Police Department and a member of the REACT task force said the group has just begun to investigate the attacks and did not have any suspects.
"We're in the evidence-gathering stage," Hsiung said. "We will be following up and investigating any leads that come up and follow wherever that leads us to."
A denial-of-service attack overwhelms a site's servers with a flood of bogus requests, effectively blocking surfers from accessing the site.
In January, hackers launched a Denial-of-service attack against Microsoft, effectively blocking access to the software giant's Web sites for parts of two days. Last year, a series of such attacks blocked access to eight major Web sites, including Yahoo, eBay and CNN.com. A Canadian teenager pleaded guilty to the attacks and will be sentenced after hearings next month.
Hackers first set their sights on Andale on March 9, bringing the site to a halt for about 12 hours, Shah said. Two more attacks followed on Thursday and Sunday, lasting a combined eight hours. Wednesday's DoS attack began at about 6 a.m. PT.
Andale has been working with Cisco and its ISP, Level 3 Communications, to stem the attacks, Shah said. The company put in place new routers from Cisco on Tuesday night that should help Andale keep its site up and help it to identify the source of the attacks, Shah said.