SQL Server - openrowset auto_create_statistics

In SQL Server, the "openrowset auto_create_statistics" configuration setting controls whether statistics are automatically created for columns when using the OPENROWSET function to access external data sources. Statistics in SQL Server are used by the query optimizer to generate optimal execution plans for queries by providing information about the distribution of data in columns. When "openrowset auto_create_statistics" is enabled, SQL Server automatically creates statistics on columns accessed through the OPENROWSET function to improve query performance.

Explanation

  • The OPENROWSET function in SQL Server allows users to access external data sources, such as Excel files, CSV files, or other databases, and retrieve data for querying and manipulation within SQL Server.
  • Statistics in SQL Server help the query optimizer make informed decisions about query execution plans by estimating the selectivity of predicates and choosing the most efficient way to retrieve data.
  • Enabling "openrowset auto_create_statistics" ensures that statistics are automatically created for columns accessed through OPENROWSET, improving query performance by providing accurate information about the data distribution in external data sources.

Security Risks

While the "openrowset auto_create_statistics" configuration setting is primarily focused on performance optimization, there are security risks that organizations should consider:

  1. Data Exposure: Automatically creating statistics on columns accessed through OPENROWSET may expose sensitive data characteristics to unauthorized users or external data sources, potentially revealing information about the data distribution and structure.
  2. Data Privacy: Statistics creation on external data sources could inadvertently expose personally identifiable information (PII) or sensitive data attributes, leading to data privacy violations if unauthorized parties gain access to statistical information.
  3. Query Injection: Malicious users may attempt to exploit the automatic creation of statistics through OPENROWSET to inject harmful queries, access restricted data, or perform unauthorized actions on external data sources, posing a risk to data security and integrity.
  4. Performance Impact: Excessive statistics creation on columns accessed through OPENROWSET may impact performance by consuming additional resources, disk space, and processing time, especially in scenarios involving large datasets or frequent data retrieval operations.

Recommendations

To mitigate security risks associated with the "openrowset auto_create_statistics" configuration setting in SQL Server, consider the following best practices:

  • Mask or anonymize sensitive data before creating statistics on external columns accessed through OPENROWSET to protect data privacy and prevent unauthorized access to sensitive information.
  • Implement access controls, authentication mechanisms, and authorization policies to restrict access to external data sources and control the creation of statistics on columns, ensuring that only authorized users can retrieve and analyze statistical information.
  • Validate and sanitize queries using OPENROWSET to prevent SQL injection attacks, unauthorized data access, or data manipulation by malicious users exploiting the automatic statistics creation functionality.
  • Monitor statistics creation activities, track data access through OPENROWSET, and audit statistical information to detect anomalies, unauthorized access attempts, or suspicious behavior related to external data retrieval.

By following these best practices and carefully managing the "openrowset auto_create_statistics" configuration setting in SQL Server, organizations can optimize query performance, enhance data analysis capabilities, and mitigate security risks related to data exposure, data privacy, query injection, and performance impact when accessing external data sources through OPENROWSET.