Extortionists have launched a series of withering attacks against online bookies in the run up the tomorrow’s Cheltenham Gold Cup.

Denial of service attacks on William Hill - Britain's second-biggest betting chain - were swiftly followed by email demands for $10,000.

Other bookies, including BetDaq and Totalbet, have been similarly attacked. The modus operandi is the same as pre-Superbowl attacks on betting sites earlier this year.

The operation of William's Hill's website was disrupted by attacks on 11 March, but the service was was back up and running in time for this week's three-day Cheltenham horse racing Festival.

"We were targeted, but were able to take the appropriate action to minimize the nature of the disruption," Graham Sharpe, a William Hill spokesman told Reuters.

Following the attack, William Hill received an email threatening further attacks unless it handed over $10,000. William Hill is refusing to give into these threats.

"We had and continue to have no intention of dealing with demands made by blackmailers," Sharpe said.

Betting exchange BetDaq was targeted in a similar attack last Friday (12 March), forcing the company to suspend services for several hours as it fought the assault.

Yesterday, two other online gambling sites - Totalbet and UKbetting - also found themselves on the receiving end of malicious attack, the London Evening Standard reports.

High street bookie Coral suffered a similar fate a few weeks ago.

Racing insiders expects punters to wager £250 million during this week's festival, up to £60 million of which will be staked online. Crooks know that if punters are unable to place their bets online they will turn other outlets. This makes bookmakers a popular target for cyber-shakedowns.

Attacks on betting sites have become increasingly commonplace since their first appearance three years ago. The latest spate follows reports last November of Eastern European crime syndicates using threats of computer hacking to extort pay-offs from online businesses in the UK.

Pete Simpson, Threatlab manager at email security outfit Clearswift, said the network of compromised PCs established by virus like MyDoom, Bagle and the rest make such attacks easier than ever.

The thousands of home users' PCs compromised by viral infection provide a ready platform from which hackers can launch attacks on bookmakers.

"It's a resource that's up for grabs," Simpson said. "I expect attackers are going through a number of proxies to hide their tracks." ®

Related Stories

DDoS attacks go through the roof
Extortionists attack Paddypower.com
East European gangs in online protection racket
DDoS protection racket targets online bookies