Hackers targeted a group of websites including The Telegraph, Betfair and UK technology news site The Register on Sunday night, putting users' private details at risk, The Guardian reports. LiveHacking has a screengrab of the Register site's hacked homepage with the hacker's message, which appeared on Sunday night.
Web users visiting those sites were shown a message in Turkish from a hackers group called Turk Guvenligi.
The hack was directed not at the sites themselves, but at their domain name host or registrar, according to The Hacker News.
The Guardian tracked down the site being used to host the hack, Blue Mile Networks, which took down the server being used.
Users of these sites are advised not to reveal their personal details on the sites until further notice. The sites affected have all re-set their DNS settings, so they appear as normal this morning. Betfair says via their community noticeboard that there could be problems for some hours ahead, although there is no evidence that member details have been compromised.
This group of hackers was previously responsible for hacking Korea's HSBC site, according to The Hacker News.
Turk Guvenligi jions hacking groups Lulzsec and Anonymous, who've made headlines in the UK this year. Earlier this summer, The Sun newspaper website was hacked by Lulzsec, while Anonymous and Lulzsec have together claimed success in hacking the CIA and Paypal websites.
On Friday, two British men aged 20 and 24 were arrested in Yorkshire and Wiltshire in connection with the Anonymous and Lulzsec hacking campaign.
Read more on the UK hacking arrests here.
UPDATE, 4:30pm:
A Telegraph spokesperson said "Our servers and customer data were not compromised during the incident. The problem was fixed last night by NetNames, a domain-name management service, who are conducting a full investigation into how the third party diverted traffic away from a number of high profile websites, including The Telegraph.”
A Betfair spokesperson said "We are monitoring the situation, but we can confirm no members' details were compromised."