I don’t understand the logic behind making a critical server like this directly accessible from the Internet, but I still find this flaw in my assessments, and we all remember the effect the SQL Slammer worm had on so many vulnerable SQL Server systems. Nevertheless, these direct attacks can lead to denial of service, buffer overflows and more.
2. Vulnerability scanning
Vulnerability scanning often reveals weaknesses in the underlying OS, the Web application or the database system itself. Anything from missing SQL Server patches to Internet Information Services (IIS) configuration weaknesses to SNMP exploits can be uncovered by attackers and lead to database server compromise. The bad guys may use open source, home-grown or commercial tools. Some are even savvy enough to carry out their hacks manually from a command prompt. In the interest of time (and minimal wheel spinning), I recommend using commercial vulnerability assessment tools like QualysGuard from Qualys Inc. (for general scanning), WebInspect from SPI Dynamics (for Web application scanning) and Next Generation Security Software Ltd.’s NGSSquirrel for SQL Server (for database-specific scanning). They’re easy to use, offer the most comprehensive assessment and, in turn, provide the best results. Figure 1 shows some SQL injection vulnerabilities you may be able to uncover.
Figure 1: Common SQL injection vulnerabilities found using WebInspect.