| If time stamps are not consistently applied and there is no common time reference, it is difficult to perform forensic analysis, in audit files, trace files/tables, and application data tables.
Time stamps generated by SQL Server must include date and time, to a granularity of one second or finer. Time is commonly expressed in Coordinated Universal Time (UTC), a modern continuation of Greenwich Mean Time (GMT), or local time with an offset from UTC. Granularity of time measurements refers to the precision available in time stamp values. Granularity coarser than one second is not sufficient for audit trail purposes, and granularity finer than one second is recommended. Time stamp values are typically presented with three or more decimal places of seconds; however, the actual granularity may be coarser than the apparent precision. For example, SQL Server's GETDATE()/CURRENT_TMESTAMP values are presented to three decimal places, but the granularity is not one millisecond: it is about 1/300 of a second.
The data types that can be used for this purpose in SQL Server are:
DATETIME2 - precision variable from a whole second down to a ten-millionth (subject to the actual precision of the hardware and operating system)
DATETIMEOFFSET - as datetime2, together with local offset from UTC
DATE, together with TIME (same precision considerations as for datetime2)
DATETIME - precision 1/300 of a second
Character-string data types allowing for at least 20 characters are also permissible, but not recommended.
SQL Server built-in functions for retrieving current timestamps are: (high precision) sysdatetime(), sysdatetimeoffset(), sysutcdatetime(); (lower precision) CURRENT_TIMESTAMP or getdate(), getutcdate().
Ensure that values recorded for tracking purposes in data tables are correctly defined and maintained. (Design decisions about which tables require audit-trail or activity-tracking columns are outside the scope of this STIG. This requirement applies only to the data type and maintenance of such columns if they do exist.)
The SMALLDATETIME data type is not precise enough for this purpose. Although it gives the impression of including a seconds component, the seconds value is always "00".
SQL Server offers a data type called TIMESTAMP that is not a representation of date and time. Rather, it is a database state counter and does not correspond to calendar and clock time. This requirement does not refer to that meaning of TIMESTAMP. To avoid confusion, Microsoft recommends using the newer name for this data type, ROWVERSION, instead. |
