In the security world, providing "what-if" scenarios can be good, but real-world examples are often required to get people to sit up and listen.For example, in my last Tech Insight, "SQL Injection Demystified," I covered some of the dangers of SQL injection and what an attacker could do if he were able to successfully exploit it. Yesterday, one of those examples caught my attention, "Yahoo! Local Hacked: Vulnerable to SQL Injection."

A "grey hat" hacker, Unu, discovered a SQL injection vulnerability in Yahoo! Local Neighbors that allowed him (or her) to do practically anything -- from viewing user information from the database to reading files on the local database server, including the /etc/passwd file. There are screenshots and some more details included in the hacker's blog.

In my Tech Insight article, I touched on several of the exploit capabilities, but as one reader pointed out, it can go much, much deeper as seen with the Heartland attacks. Through SQL injection, attackers were able to gain access to the local database server, pivot to attack other important servers, and install malware with keylogging and network sniffing capabilities. It's an incredibly powerful vector for attack, and one that I've had developers dismiss by saying it's only an error message, and you can't do anything with that.

Even if an attacker can't get enough privileges to start executing code and making changes on the local database server's system, rights to edit content within the database can be just as powerful. Imagine that an attacker starts editing your Web content to include hidden iFrames with an exploit for the latest ActiveX or Flash vulnerability. Or say he uses Browser Rider or BeEF to inject a JavaScript hook to hijack Web browsers of people viewing your site. From there, he just needs to compromise the right credentials, and he's in.

A very good Webcast that covers scenarios like SQL injection being used to hijack Web browsers is the "Invasion of the Browser Snatchers: Part I," featuring Ed Skoudis and Kevin Johnson of InGuardians. The Webcast is about an hour long. Ed and Kevin both do a very good job of explaining how SQL injection attacks work and just how much evil can be wrought.

John H. Sawyer is a senior security engineer on the IT Security Team at the University of Florida. The views and opinions expressed in this blog are his own and do not represent the views and opinions of the UF IT Security Team or the University of Florida. When John's not fighting flaming, malware-infested machines or performing autopsies on blitzed boxes, he can usually be found hanging with his family, bouncing a baby on one knee and balancing a laptop on the other. Special to Dark Reading.