The DBMS must manage resources to limit the effects of information flooding types of Denial of Service (DoS) incidents.

From Oracle Database 12c Security Technical Implementation Guide

Part of SRG-APP-000247-DB-000134

Associated with: CCI-001095

SV-76307r3_rule The DBMS must manage resources to limit the effects of information flooding types of Denial of Service (DoS) incidents.

Vulnerability discussion

In the case of application DoS incidents, care must be taken when designing the application to ensure the application makes the best use of system resources. SQL queries have the potential to consume large amounts of CPU cycles if they are not tuned for optimal performance. Web services containing complex calculations requiring large amounts of time to complete can bog down if too many requests for the service are encountered within a short period of time.The methods employed to meet this requirement will vary depending upon the technology the application utilizes. However, a variety of technologies exist to limit, or in some cases, eliminate the effects of application-related DoS incidents. Employing increased capacity and bandwidth combined with specialized application layer protection devices and service redundancy may reduce the susceptibility to some DoS problems.Databases are particularly susceptible to SQL-related DoS issues. Databases that do not protect against resource-intensive SQL queries may experience dramatic slowdowns from malicious attacks or accidental DoS incidents related to SQL queries. What constitutes a resource-intensive query has to be determined locally, taking into account the purpose of the database and the needs of the various classes of user.

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Review Oracle user profiles. Connect to Oracle as SYSDBA. Use the following query to determine the established profiles and the users and resource limits assigned to them. select a.username, a.profile, b.resource_name, b.resource_type, b.limit from dba_users a, dba_profiles b where a.profile = b.profile and resource_type='KERNEL' order by a.profile; If the configuration does not include profile limits on resource-intensive SQL queries, or if users are not assigned to profiles appropriate to their needs, this is a finding.

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Configure Oracle profile(s) to set resource limits appropriate to each class of user. SESSIONS_PER_USER Specify the number of concurrent sessions to which you want to limit the user. CPU_PER_SESSION Specify the CPU time limit for a session, expressed in hundredth of seconds. CPU_PER_CALL Specify the CPU time limit for a call (a parse, execute, or fetch), expressed in hundredths of seconds. CONNECT_TIME Specify the total elapsed time limit for a session, expressed in minutes. IDLE_TIME Specify the permitted periods of continuous inactive time during a session, expressed in minutes. Long-running queries and other operations are not subject to this limit. LOGICAL_READS_PER_SESSION Specify the permitted number of data blocks read in a session, including blocks read from memory and disk. LOGICAL_READS_PER_CALL Specify the permitted number of data blocks read for a call to process a SQL statement (a parse, execute, or fetch). PRIVATE_SGA Specify the amount of private space a session can allocate in the shared pool of the system global area (SGA). Refer to size_clause for information on that clause. COMPOSITE_LIMIT (This limit applies only when using shared server architecture. The private space for a session in the SGA includes private SQL and PL/SQL areas, but not shared SQL and PL/SQL areas.) Specify the total resource cost for a session, expressed in service units. Oracle Database calculates the total service units as a weighted sum of CPU_PER_SESSION, CONNECT_TIME, LOGICAL_READS_PER_SESSION, and PRIVATE_SGA. The user profile, ORA_STIG_PROFILE, has been provided (starting with Oracle 12.1.0.2) to satisfy the STIG requirements pertaining to the profile parameters. Oracle recommends that this profile be customized with any site-specific requirements and assigned to all users where applicable. Note: It remains necessary to create a customized replacement for the password validation function, ORA12C_STRONG_VERIFY_FUNCTION, if relying on this technique to verify password complexity.

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