News

Exploit Targets Microsoft Access Database

• By Jabulani Leffall
• December 13, 2007

The United States Computer Emergency Readiness Team (CERT), a subset of the U.S. Department of Homeland Security, issued an advisory stating that it has become aware of active exploitation using malicious databases, "to possibly install malware or other destructive viral programs."

A hack of the system through Access Database can happen if a database administrator or user opens an .mdb file -- the files most common in relational databases such as Access -- sent as an attachment through an e-mail message. If designed correctly, security experts say the malicious code can infiltrate the workstation running Access and run nefarious code with an elevated privilege level, effectively entering the network through a database.

Like many exploits, code execution in this case is contingent upon what's called buffer overflow, where a program such as Access would be attempting to store data beyond the boundary of fixed-length buffers configured by database administrators. The surplus data, like water spilling out a full cup, overwrites other memory locations causing a system crash and heightening the risks related to any vulnerability.

Security researchers last month discovered a similar buffer overflow bug in the Microsoft Jet DataBase engine, which is used to analyze and distribute Access files on database tables.

But the good news with the latest bug is that IT pros don't have to worry about it and aren't likely to see it unless they're also a database administrator.

"This .mdb file vector is more likely to be used in a targeted attack where the hacker knows the person opening the file is accustomed to using Access and sees these types of files often," said Marc Fossi, a manager at Symantec Security Response. "There have been similar issues in Access before, but on the plus side most people don't deal with these files and wouldn't recognize them."

Moreover, in most enterprise environments DBAs and other administrators are savvy enough to block this file type unless they know exactly where it's from. And in most cases, such files are blocked in both Microsoft Outlook and Internet Explorer.