17th Annual Computer Security Applications Conference
December 10-14, 2001
New Orleans, Louisiana


DAIS: A Real-time Data Attack Isolation System for Commercial Database Applications

Peng Liu
University of Maryland Baltimore County
USA

Traditional database security mechanisms are very limited in defending successful data attacks. Authorized but malicious transactions can make a database useless by impairing its integrity and availability. This paper presents the design of a real-time data attack isolation system, denoted DAIS. DAIS isolates likely suspicious actions before a definite determination of intrusion is reported. In this way, the database can be immunized from many malicious transactions. DAIS is a COTS-DBMS-specific implementation of a general isolation algorithm that we developed in [Liu et. al. 2000]. In this paper, the design of the first DAIS prototype, which is for Oracle Server 8.1.6, is discussed. DAIS uses triggers and transaction profiles to keep track of the items read and written by transactions, isolates attacks by rewriting user SQL statements, and is transparent to end users. The DAIS design is very general. In addition to Oracle, it can be easily adapted to support many other database application platforms such as Microsoft SQL Server, Sybase, and Informix.

Keywords: Isolation, Intrusion Tolerance, Database Security

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