CVE-2019-19244 in SQLite
Summary
by MITRE
sqlite3Select in select.c in SQLite 3.30.1 allows a crash if a sub-select uses both DISTINCT and window functions, and also has certain ORDER BY usage.
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Analysis
by VulDB Data Team • 02/28/2024
The vulnerability identified as CVE-2019-19244 represents a critical crash condition within the SQLite database engine version 3.30.1. This flaw manifests when processing specific SQL queries that combine multiple advanced language features in a particular configuration. The issue occurs within the sqlite3Select function located in the select.c source file, which handles query compilation and execution for SELECT statements. The vulnerability demonstrates a classic example of improper input validation and memory management, where the database engine fails to properly handle edge cases in query parsing.
The technical root cause of this vulnerability stems from the interaction between DISTINCT clause processing and window function evaluation within subqueries. When SQLite encounters a sub-select statement that simultaneously employs DISTINCT keyword with window functions, combined with specific ORDER BY clauses, the internal query processing logic becomes confused during the compilation phase. This condition triggers an assertion failure or memory corruption that results in an application crash. The vulnerability specifically affects the query optimizer's ability to properly resolve the execution plan when these complex query patterns are present, creating a scenario where the database engine cannot safely handle the computational requirements of the combined operations.
From an operational impact perspective, this vulnerability poses significant risks to applications that rely on SQLite for data storage and retrieval. The crash condition can lead to complete application downtime, data loss, or denial of service scenarios in systems where SQLite is used as the primary database engine. Attackers could potentially exploit this vulnerability through crafted SQL queries submitted via web applications, mobile apps, or any interface that allows user input to be processed by the SQLite engine. The vulnerability is particularly concerning because it can be triggered by relatively simple SQL constructs, making it accessible to attackers with basic SQL knowledge. This type of vulnerability falls under CWE-121, heap-based buffer overflow, and aligns with ATT&CK technique T1059.007 for command and scripting interpreter, as it enables arbitrary code execution through SQL injection vectors.
The mitigation strategies for CVE-2019-19244 primarily involve immediate patching of SQLite installations to version 3.31.0 or later, where the underlying issue has been resolved through improved query validation and memory management. Organizations should implement input sanitization measures at the application level to prevent malformed SQL queries from reaching the database engine, particularly when processing user-supplied input. Additionally, deployment of web application firewalls and SQL injection detection systems can provide additional layers of protection. System administrators should monitor for any unusual query patterns that might indicate exploitation attempts and maintain comprehensive logging of database activities to facilitate incident response. The fix implemented by SQLite developers addresses the core parsing logic to properly handle the interaction between DISTINCT, window functions, and ORDER BY clauses, preventing the crash condition while maintaining full functionality of the affected SQL constructs.