CVE-2023-31655: Redis Denial of Service Vulnerability

CVE-2023-31655 Overview

CVE-2023-31655 is a Denial of Service (DoS) vulnerability affecting Redis version 7.0.10. The vulnerability stems from a segmentation violation that can be triggered by remote attackers through unspecified vectors, potentially causing service disruption and availability issues for Redis deployments.

Critical Impact

This vulnerability allows unauthenticated remote attackers to cause a Denial of Service condition by triggering a segmentation fault in Redis, leading to service crashes and potential data availability issues.

Affected Products

• Redis 7.0.10
• Redis deployments using RedisRaft module
• NetApp products incorporating vulnerable Redis versions

Discovery Timeline

• May 18, 2023 - CVE-2023-31655 published to NVD
• November 21, 2024 - Last updated in NVD database

Technical Details for CVE-2023-31655

Vulnerability Analysis

This vulnerability is classified as a Denial of Service (DoS) issue caused by a segmentation violation (segfault) within Redis 7.0.10. A segmentation violation occurs when a program attempts to access a memory location that it is not permitted to access, or attempts to access memory in a way that is not allowed. In the context of Redis, this type of memory access violation causes the Redis server process to crash, immediately terminating all client connections and disrupting data operations.

The vulnerability is particularly concerning because it can be triggered remotely over the network without requiring authentication or user interaction. This makes it an attractive target for attackers seeking to disrupt Redis-based infrastructure, including caching layers, session stores, and real-time data processing systems.

Root Cause

The root cause of this vulnerability is a memory access violation within Redis 7.0.10 that leads to a segmentation fault. While the specific code path triggering the segfault has not been fully disclosed in public advisories, segmentation violations in database systems typically arise from improper pointer handling, boundary condition errors, or race conditions in memory management routines. The vulnerability appears to be related to the RedisRaft module based on the associated GitHub issue tracking.

Attack Vector

The attack vector for CVE-2023-31655 is network-based, requiring no privileges or user interaction to exploit. An attacker with network access to a vulnerable Redis instance can send specially crafted requests that trigger the segmentation violation, causing the Redis server to crash. This can be executed remotely against any exposed Redis service running the affected version.

The exploitation mechanism involves sending requests that cause Redis to access invalid memory regions, resulting in a SIGSEGV signal and process termination. The specific request format or command sequence that triggers this condition has not been publicly documented, which may limit widespread exploitation but does not eliminate the risk.

Detection Methods for CVE-2023-31655

Indicators of Compromise

• Redis server processes terminating unexpectedly with segmentation fault signals (SIGSEGV)
• Core dump files generated from Redis crashes in system log directories
• Repeated Redis service restarts in monitoring systems
• Anomalous network traffic patterns targeting Redis ports (default: 6379)

Detection Strategies

• Monitor system logs for Redis process crashes and segmentation fault events
• Configure Redis to generate core dumps and analyze them for crash signatures
• Implement network monitoring to detect unusual connection patterns to Redis services
• Deploy intrusion detection rules to identify potential exploitation attempts against Redis

Monitoring Recommendations

• Enable Redis logging at DEBUG level during investigation periods to capture detailed operation traces
• Configure monitoring alerts for Redis process availability and unexpected restarts
• Implement health checks that verify Redis responsiveness and memory state
• Review Redis slow log and client connection logs for anomalous commands or connection sources

How to Mitigate CVE-2023-31655

Immediate Actions Required

• Upgrade Redis to a patched version beyond 7.0.10 where the segmentation violation has been addressed
• Restrict network access to Redis instances using firewall rules and network segmentation
• Enable Redis authentication using the requirepass configuration directive
• Consider placing Redis behind a proxy or application layer that can filter malicious requests

Patch Information

Redis users should upgrade to a patched version that addresses this segmentation violation. Consult the GitHub Issue Discussion for technical details on the fix and the NetApp Security Advisory for guidance on affected NetApp products. Always verify the integrity of downloaded packages and test upgrades in a staging environment before deploying to production.

Workarounds

• Implement network-level access controls to limit Redis exposure to trusted clients only
• Deploy Redis behind a reverse proxy or load balancer with request filtering capabilities
• Configure Redis protected mode and bind to specific interfaces rather than all network interfaces
• Enable Redis TLS encryption to add an additional layer of connection security
• Implement rate limiting on connections to Redis to mitigate potential DoS attack impact

# Configuration example - Redis security hardening
# Edit redis.conf to implement protective measures

# Bind to specific interface only (not 0.0.0.0)
bind 127.0.0.1 192.168.1.100

# Enable protected mode
protected-mode yes

# Require authentication
requirepass your_strong_password_here

# Rename dangerous commands
rename-command FLUSHALL ""
rename-command CONFIG ""
rename-command DEBUG ""

# Set connection limits
maxclients 1000
timeout 300