A hacker broke into Google's main official blog and posted a false message, saying the company had decided to cancel a joint project with eBay.
The intrusion marks the second time this year that Google's official blog has fallen into unauthorised hands. In March, Google staffers deleted the so-called Google Blog by mistake and someone briefly took control of the web address.
In Saturday's incident, someone exploited a bug in Blogger, the Google weblog publishing service on which Google Blog is hosted. The hacker published a note riddled with grammatical and spelling errors that said Google had ended its click-to-call advertising project with eBay because it was "monopolistic".
The next day, Karen Wickre, from the Google Blog team, alerted readers about the false posting and said the Blogger bug had been fixed, without detailing the breach. The eBay project remains alive and well, she wrote on the blog.
The Google Blog is one of the company's main communication tools. As official corporate messages similar to press releases, its postings often trigger news reports, analyst recommendations and investor decisions.
Key to Google's success is that individuals and organisations trust that the company will keep their confidential information safe. Public displays of security vulnerabilities erode that confidence.
On the consumer side, Google keeps massive logs of search queries, a portion of which are directly linked to specific Google account holders who have given the company permission to track their search activities.
For consumers, it also stores personal information such as email messages, digital photos and calendar entries via a variety of online services such as its Gmail web email service, Picasa photo manager and Google Calendar.