CVE-2020-13630: SQLite Use-After-Free Vulnerability

CVE-2020-13630 Overview

CVE-2020-13630 is a use-after-free vulnerability in SQLite's Full-Text Search 3 (FTS3) extension. The flaw exists in the fts3EvalNextRow function within ext/fts3/fts3.c and is related to the snippet feature. This memory corruption vulnerability affects SQLite versions prior to 3.32.0 and can potentially be exploited by a local attacker who can execute specially crafted SQL queries against a vulnerable SQLite database.

Critical Impact

A successful exploitation of this use-after-free vulnerability could allow an attacker to corrupt memory, potentially leading to arbitrary code execution, denial of service, or information disclosure within the context of the application using SQLite.

Affected Products

• SQLite versions prior to 3.32.0
• Apple macOS, iOS, iPadOS, tvOS, watchOS, iCloud, and iTunes
• Canonical Ubuntu Linux 16.04 ESM, 18.04 LTS, 19.10, and 20.04 LTS
• Debian Linux 9.0
• Fedora 32
• NetApp Cloud Backup, SolidFire, and HCI Compute Node
• Oracle Communications Network Charging and Control, Outside In Technology, and ZFS Storage Appliance Kit
• Siemens SINEC Infrastructure Network Services
• Brocade Fabric Operating System

Discovery Timeline

• 2020-05-27 - CVE-2020-13630 published to NVD
• 2024-11-21 - Last updated in NVD database

Technical Details for CVE-2020-13630

Vulnerability Analysis

This vulnerability is classified as CWE-416 (Use After Free), a dangerous memory corruption issue that occurs when a program continues to use a pointer after the memory it references has been freed. In the context of SQLite's FTS3 extension, the vulnerability manifests in the fts3EvalNextRow function, which is responsible for iterating through full-text search results.

The FTS3 extension provides full-text indexing capabilities for SQLite databases, allowing users to perform efficient text searches. The snippet feature, which is implicated in this vulnerability, generates excerpts of matching text from search results. During the processing of these snippets, improper memory management leads to a situation where freed memory can be accessed and potentially manipulated.

Root Cause

The root cause of CVE-2020-13630 lies in improper memory lifecycle management within the FTS3 module's row evaluation logic. When processing full-text search queries that utilize the snippet function, the code may free memory associated with a cursor or result set while still maintaining active references to that memory. Subsequent operations that attempt to access this freed memory trigger the use-after-free condition.

This type of vulnerability typically arises from complex state management in database cursor operations, where multiple code paths can lead to memory being freed prematurely while other parts of the code still expect valid data to be present.

Attack Vector

Exploitation of this vulnerability requires local access and the ability to execute SQL queries against a SQLite database. An attacker would need to craft malicious SQL statements that utilize the FTS3 full-text search functionality with the snippet feature in a way that triggers the use-after-free condition.

The attack scenario involves constructing specific queries that manipulate the internal state of the FTS3 cursor during row evaluation. When the vulnerable code path is triggered, the attacker may be able to:

1. Execute SQL queries that create and populate FTS3 virtual tables
2. Craft search operations using the snippet function with specific parameters
3. Trigger the memory corruption through carefully timed operations
4. Potentially gain control over program execution by corrupting function pointers or other critical data structures

For detailed technical information about the vulnerability mechanism, see the SQLite source code commit that addresses this issue.

Detection Methods for CVE-2020-13630

Indicators of Compromise

• Unexpected application crashes or segmentation faults in applications using SQLite with FTS3 functionality
• Memory corruption errors or heap corruption messages in application logs
• Anomalous SQL query patterns involving FTS3 snippet functions with unusual parameters
• Core dumps showing memory access violations within SQLite FTS3 module functions

Detection Strategies

• Implement application-level monitoring for SQLite query patterns, specifically watching for unusual FTS3 snippet operations
• Deploy memory sanitization tools (AddressSanitizer, Valgrind) in development and testing environments to detect use-after-free conditions
• Monitor for unexpected process terminations in applications that heavily utilize SQLite full-text search capabilities
• Utilize SentinelOne's behavioral analysis to detect memory corruption exploitation attempts

Monitoring Recommendations

• Enable verbose logging for database-intensive applications to capture SQL query patterns
• Implement integrity monitoring on SQLite database files for unexpected modifications
• Configure crash reporting and analysis for applications using vulnerable SQLite versions
• Establish baseline behavior profiles for applications using FTS3 to detect anomalous activity

How to Mitigate CVE-2020-13630

Immediate Actions Required

• Upgrade SQLite to version 3.32.0 or later immediately on all affected systems
• Identify all applications and systems in your environment that embed or depend on SQLite
• Apply vendor-specific patches for affected operating systems including Apple, Ubuntu, Debian, and Fedora distributions
• If immediate patching is not possible, consider disabling FTS3 functionality where feasible

Patch Information

SQLite has addressed this vulnerability in version 3.32.0 and later. The fix is available in commit 0d69f76f0865f962 in the SQLite source repository. Multiple vendors have released patches for their products:

• Apple: Security updates available via HT211843, HT211844, HT211850, HT211931, HT211935, and HT211952
• Ubuntu: USN-4394-1
• FreeBSD: FreeBSD-SA-20:22
• Oracle: Patches in July 2020 CPU and October 2020 CPU
• Siemens: SSA-389290
• NetApp: NTAP-20200608-0002

Workarounds

• Disable FTS3/FTS4 virtual table support if full-text search functionality is not required in your application
• Implement input validation to restrict the use of snippet functions in user-supplied SQL queries
• Apply defense-in-depth measures such as running SQLite-dependent applications with minimal privileges
• Consider using FTS5 as an alternative, as it may not be affected by this specific vulnerability

# Verify SQLite version on Linux systems
sqlite3 --version

# Check if FTS3 is enabled in a SQLite build
sqlite3 :memory: "SELECT sqlite_compileoption_used('ENABLE_FTS3');"

# Update SQLite on Ubuntu/Debian
sudo apt-get update && sudo apt-get install sqlite3 libsqlite3-0

# Update SQLite on Fedora
sudo dnf update sqlite