The website for the open-source MySQL database was hacked and used to serve malware to visitors yesterday.

Security vendor Armorize noticed the problem at around 5am Pacific Time. Hackers had installed JavaScript code that threw a variety of known browser attacks at visitors to the site, so those with out-of-date browsers or unpatched versions of Adobe Flash, Reader or Java on their Windows PCs could have been quietly infected with malicious software.

By just after 11 am, the issue had been cleaned up, said Wayne Huang, Armorize's CEO. He thinks the malicious code was on the site for less than a day.

Huang said that the attackers used the Black Hole exploit kit to attack visitors to the site, but his team had not yet figured out what the malicious software that it installed was designed to do. Typically, criminals install malware to steal victims' passwords, pop-up advertisements for fake antivirus software, or to create botnet computers that can be rented out to others.

Oracle, which manages the MySQL.com project, was still investigating the issue and unable to comment.

Highly trafficked open-source websites such as MySQL.com have been hit hard in recent months. In the past weeks the Linux Foundation was forced to take a number of websites offline, including Kernel.org and Linux.com after a compromise. And MySQL.com itself was hit earlier this year.

The hackers who hit MySQL.com in March posted a list of usernames and passwords after their hack, and that data may have been used to break into the site again, according to Maxim Goncharov, a senior threat researcher with Trend Micro.

In Russian underground forums, a hacker named 'sourcec0de' has been shopping root access to the MySQL.com servers recently, Goncharov said. His price? $3,000.

It's not clear whether sourcec0de really did have access to the MySQL.com website, but he did post screenshots that appeared to show that he had root access to the MySQL servers, Goncharov said in a blog posting.