Think your database server is safe? You may want to double-check. According to security researcher David Litchfield, there are nearly half a million database servers exposed on the Internet, without firewall protection.

Litchfield took a look at more than 1 million randomly generated IP addresses, checking them to see if he could access them on the IP ports reserved for Microsoft SQL Server or Oracle's database. The results? He found 157 SQL servers and 53 Oracle servers. Litchfield then relied on known estimates of the number of systems on the Internet to arrive at his conclusion: "There are approximately 368,000 Microsoft SQL Servers... and about 124,000 Oracle database servers directly accessible on the Internet," he wrote in his report, due to be made public next week.

This is not the first time that Litchfield, managing director of NGSSoftware, has conducted this type of research. Two years ago, he released his first Database Exposure Survey, estimating that there were about 350,000 Microsoft and Oracle databases exposed.

This 2007 version of the Database Exposure Survey is set to be published Monday on Litchfield's Databasesecurity.com Web site. IDG News was given a preliminary copy of the findings.

With no firewall, databases are exposed to hackers, putting corporate data at risk. Litchfield said that, given the amount of press generated by corporate data breaches over the past two years, it's amazing to find that there are more databases exposed than ever before. "I think it's terrible," he said in an interview. "We all run around like headless chickens following these data breach headlines... organizations out there really don't care. Why are all these sites hanging out there without the protection of a firewall?"

This year's Oracle tally is actually down from Litchfield's 2005 estimate, which counted 140,000 Oracle systems. That same study placed the SQL server total at 210,000.

The security researcher wasn't sure why Oracle's numbers had declined while Microsoft's had risen. "Microsoft's technology is certainly easier to install. Maybe the increase in SQL server numbers is simply a function of that," he said.

In the 2005 survey, Litchfield found an even larger number of the open source MySQL databases outside of the firewall. The 2007 survey does not count MySQL, however.

There was one other disturbing finding in Litchfield's 2007 survey: Many of these unprotected databases are also unpatched. In fact, 4 percent of the SQL Server databases Litchfield found were still vulnerable to the flaw that was exploited by 2003's widespread SQL Slammer worm. "People aren't protecting themselves with firewalls, and the patch levels are atrocious," he said.

About 82 percent of the SQL Servers were running older SQL Server 2000 software, and less than half of those had the product's latest Service Pack updates installed. On the Oracle side, 13 percent of the servers were running older versions of the database that no longer receive patches. These Oracle 9.0 and earlier databases are known to have security vulnerabilities, Litchfield said.

Litchfield, who wrote the proof of concept code that was eventually used by Slammer, said that this many unsecured databases is enough to sustain another worm outbreak. "There's certainly potential there," he said. "So the question is what's the likelihood? [That's] much more difficult to answer."