Software Engineering Institute

Oracle9i Database authenticates and manages database connections via Oracle Transparent Network Substrate (TNS ) Listeners. According to a report by NGSSoftware, a buffer overflow condition occurs when a TNS Listener process attempts to log an error condition caused by a TNS request containing an overly long SERVICE_NAME parameter. An attacker may be able to exploit this vulnerability by sending a specially crafted TNS request to a vulnerable Oracle Listener.

According Oracle Security Alert #34, Microsoft Windows and IBM VM versions of Oracle9i Database (9.0.x) are affected by this vulnerability.

An unauthenticated remote attacker could execute arbitrary code or cause a denial of service on a vulnerable system. Oracle Listener processes may run with SYSTEM privileges on Windows NT and Windows 2000 systems.

Apply a Patch

Oracle Security Alert #34 provides information on patches that address this vulnerability.

Restrict Access

Where possible, limit access to trusted users, hosts, and networks. Use firewall or router ACLs (access control lists) to restrict connections to the port used by Oracle TNS Listeners, 1521/tcp by default. Enable the Oracle Net feature called "TCP valid node checking" by modifying $ORACLE_HOME/NETWORK/ADMIN/SQLNET.ORA ($ORACLE_HOME/NETWORK/ADMIN/PROTOCOL.ORA in Oracle8i and prior releases) as follows:

tcp.validnode_checking = YES
tcp.invited_nodes = {list of IP addresses}
tcp.excluded_nodes = {list of IP addresses}

Note that restricting access to Oracle TNS Listeners will not prevent exploitation of this vulnerability.