This paper presents the design and implementation of an on-the-fly damage assessment and repair tool
for intrusion tolerant commercial database applications, called ODAR. ODAR is a COTS-DBMSspecific
implementation of a general on-the-fly damage assessment and repair approach developed by P.
Ammann, S. Jajodia, and P. Liu in [18]. The general approach, given a set of malicious transactions
reported by an intrusion detector, locates and repairs the damage caused by each malicious transaction
on the database, along with the damage caused by any benign transaction that is affected, directly or
indirectly, by a malicious transaction. The general approach locates and repairs damage on-the-fly
without the need to periodically halt normal transaction processing. In this paper, the development of the
first ODAR prototype, which is for Oracle Server 8.1.6, is discussed. ODAR uses triggers and
transaction profiles to keep track of the read and write operations of transactions, locates damage by
tracing the affecting relationships among transactions along the history, and repairs damage by
composing and executing some specific UNDO transactions. ODAR is transparent to on-going user
transactions and 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. To our best
knowledge, ODAR is the first tool that can do automatic on-the-fly damage assessment and repair for
commercial database applications.