CVE-2020-35527: SQLite Buffer Overflow Vulnerability

CVE-2020-35527 Overview

CVE-2020-35527 is an out-of-bounds access vulnerability in SQLite version 3.31.1. The vulnerability occurs when processing ALTER TABLE statements on views that contain a nested FROM clause. This memory corruption flaw can be exploited remotely without authentication, potentially leading to arbitrary code execution, data corruption, or denial of service conditions in applications that utilize SQLite as their database engine.

Critical Impact

This out-of-bounds access vulnerability in SQLite can be exploited remotely without authentication, potentially allowing attackers to execute arbitrary code, corrupt data, or crash applications using the affected SQLite library.

Affected Products

• SQLite 3.31.1
• NetApp ONTAP Select Deploy Administration Utility

Discovery Timeline

• 2022-09-01 - CVE CVE-2020-35527 published to NVD
• 2024-11-21 - Last updated in NVD database

Technical Details for CVE-2020-35527

Vulnerability Analysis

This vulnerability is classified as CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer). The flaw exists in SQLite's handling of ALTER TABLE operations when applied to database views that contain nested FROM clauses. When the ALTER TABLE command processes such views, the parser fails to properly validate memory boundaries, resulting in out-of-bounds memory access.

The vulnerability can be triggered remotely through any application that accepts and processes SQL statements using the vulnerable SQLite library. Since SQLite is embedded in countless applications, web browsers, mobile apps, and enterprise systems, the attack surface is substantial. An attacker capable of injecting or influencing SQL statements processed by the vulnerable library could exploit this flaw to read or write memory outside intended boundaries.

Root Cause

The root cause of CVE-2020-35527 lies in SQLite's insufficient bounds checking when the ALTER TABLE statement operates on views with complex nested FROM clauses. The internal parser and memory management routines fail to account for the additional complexity introduced by nested subqueries in view definitions, leading to improper memory buffer operations. This oversight allows memory access beyond the allocated boundaries when processing these specific SQL constructs.

Attack Vector

The attack vector is network-based, as indicated by the CVSS assessment. An attacker can exploit this vulnerability by:

1. Identifying an application that uses SQLite 3.31.1 and accepts user-influenced SQL queries
2. Crafting an ALTER TABLE statement targeting a view with a nested FROM clause structure
3. Sending the malicious SQL statement to the target application
4. Triggering the out-of-bounds memory access, which could result in information disclosure, code execution, or application crash

The vulnerability requires no authentication or user interaction, making it particularly dangerous in exposed environments where untrusted SQL input may be processed.

Detection Methods for CVE-2020-35527

Indicators of Compromise

• Application crashes or unexpected terminations when processing ALTER TABLE statements on views
• Memory corruption errors or segmentation faults in SQLite-dependent applications
• Unusual memory access patterns in applications utilizing SQLite database operations
• Error logs showing SQLite-related failures during view modification operations

Detection Strategies

• Monitor for anomalous ALTER TABLE queries targeting views with nested FROM clause structures
• Implement application-level logging for all SQL DDL operations, especially those modifying views
• Deploy memory protection mechanisms and crash analysis tools to detect exploitation attempts
• Use static analysis tools to identify applications using vulnerable SQLite 3.31.1 versions

Monitoring Recommendations

• Inventory all systems and applications using SQLite and identify those running version 3.31.1
• Enable detailed SQL query logging in applications that process untrusted input
• Monitor system logs for crash reports or memory corruption indicators in SQLite-dependent services
• Implement network-level monitoring for suspicious SQL payloads targeting SQLite functions

How to Mitigate CVE-2020-35527

Immediate Actions Required

• Upgrade SQLite to a patched version that addresses CVE-2020-35527
• Review and restrict ALTER TABLE privileges in applications processing untrusted SQL input
• Implement input validation to reject or sanitize potentially malicious SQL constructs
• Apply vendor patches for affected products including NetApp ONTAP Select Deploy Administration Utility

Patch Information

SQLite has released a fix for this vulnerability. The patch details are available in the SQLite Code Change Information documentation. Organizations using NetApp products should review the NetApp Security Advisory NTAP-20221111-0007 for specific guidance on affected ONTAP Select Deploy Administration Utility deployments.

Workarounds

• Restrict ALTER TABLE permissions to trusted administrators only until patching is complete
• Implement SQL query filtering to block ALTER TABLE operations on views with nested FROM clauses
• Isolate SQLite-dependent applications from untrusted network access where feasible
• Consider using prepared statements and parameterized queries to limit SQL injection attack surfaces