The outfit that manages Internet addresses for Ireland’s national .ie domain has temporarily taken some of its systems offline while officials investigate a security breach that temporarily hijacked the Irish websites for Google and Yahoo.

A short note on the homepage of the IE Domain Registry said the move followed a "security incident on Tuesday 9th October, involving two high profile .ie domains that has warranted further investigation and some precautionary actions on the part of the IEDR." Several independent Web posts, including those on Twitter and the site of a .ie domain registrar (Google cache here) identified the sites as Google.ie and Yahoo.ie. People trying to visit those addresses were briefly redirected to a fraudulent server as a result of "unauthorised access to one Registrar's account which resulted in the change to the DNS nameserver records for the two .ie domains," the latter blog post reported, citing IEDR CEO David Curtin.

Both of the affected sites, according to whois records, are managed by MarkMonitor, a company that protects the online brands of its customers. Sophos security expert Graham Cluley reported that the breach caused the IEDR to incorrectly point users to domain name system name servers at farahatz.net, which appear to be located in Indonesia.

There are no reports of people being redirected to websites that tried to install malicious software on their computers or trick visitors into divulging passwords or other personal information. Still, the incident is a reminder that a single misconfiguration to the Internet's routing system can have serious consequences for large numbers of people visiting brand-name sites.

The IEDR advisory said officials with the Garda Bureau of Fraud Investigation, Ireland's national police force, commenced an investigation on Wednesday. IEDR's Web interfaces aren't affected by the temporary suspension, allowing over two-thirds of its registrars to operate normally, the officials said, adding that public access to .ie websites and e-mail are also unaffected.