A Context-Aware Approach to SQL Injections

In an age of multimillion-dollar data breaches, detecting and thwarting SQL injection attacks against databases has never been more important.

However, doing that means more than analyzing applications for vulnerabilities during the development process. It also means being able to monitor and detect whats happening to a database.

Sentrigo, based in Woburn, Mass., is hoping to make its mark by bringing context-aware technology down to the database level to detect SQL injection attacks, a tactic company officials said is superior to other methods of detection.

Sentrigos product, Hedgehog, directly monitors the databases memory and examines the context from which the SQL statements originate, as well as the types of commands used and the database access privileges of the user.

Context-based detection is better than other methods for three reasons, said Sentrigo Chief Technology Officer Slavik Markovich.

"One, unlike signature-based methods, it doesnt rely on expression matching in the SQL statement itself and therefore cannot be evaded using small variations on the original exploit," he said.

"Two, it is false-positive proof. If you detect, for example, a privilege grant command attempt from within a package that would have no business issuing such commands, you can know for sure it is the result of an exploit. There is simply no reason for anyone to do this for kosher reasons."

The third reason, said Markovich, is that because context-based detection uses context to determine the legitimacy of command coming from packages, it is effective against zero-day exploits.

"We dont need to know the exact SQL injection or even somewhat different hacking methods—if they target built-in packages and attempt privilege escalation we will catch it," he said.

Officials at Imperva, which competes with the smaller Sentrigo in database security, said a more holistic approach to combating SQL injections is needed, not just monitoring the database for activity at the object level. Imperva introduced profile-based detection technology known as Dynamic Profiling in 2002, which creates a model profile of every user and blocks malicious activity and policy violations by comparing user behavior to the profile.

"Impervas SecureSphere provides more effective security by protecting the database as well as all avenues for accessing the database including Web/application servers, application processing requests, the operating system and the protocols being used to transport sensitive information," said Imperva CTO Amichai Shulman.

"If any of these elements are left unmonitored and unprotected, a product is only securing the front door, while the back door is wide open, leaving data at risk."

To Shulman, monitoring database activity without any information about the application and Web side of the transaction provides only half the context necessary to make accurate decisions.

"Both halves of the equation are needed to block all attacks, while avoiding false positives and permitting legitimate usage," he said.

In an ideal world, SQL injection problems would be solved by removing the vulnerability from the Web application to begin with by using tools from companies such as Watchfire and others, said Neil MacDonald, an analyst with Gartner.

Sentrigo upgrades database security product. Click here to read more.

"What Sentrigo is talking about is not conceptually different than Web application firewalls, which can look at inbound and outbound traffic and enforce rules on what the application receives as input and what the application should send as output," he said.

"Adding context into security decisions results in better, more relevant security decisions—for example, fewer false positives and false negatives. This trend is occurring in all aspects of information security. "

Still, analyst Eric Ogren of the Ogren Group is skeptical that an organization that will block a SQL instruction from executing based on a dynamic assessment of abhorrent behavior. Organizations need both a signature and context-based approach for effective security, he said.

"Its hard to argue with the value of signatures for predictable reactions to know security events," he said. "However, vendor signatures can never catch anything new or reflect unique business deployments. Sentrigos approach is very useful in alerting security to a problem, and the problem will be corrected with virtual patching, signature filters, or other static means."

Ogren added that there is no easy answer for database security. "It is not a defense-in-depth story; rather [it requires] an integrated approach," he said.

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