CVE-2023-41056: Redis In-Memory Database Memory Buffer Resize Vulnerability Explained

Redis, the popular in-memory data structure store widely used for caching and building real-time applications, has been found vulnerable to a critical security issue allowing attackers to potentially exploit memory overflow and execute malicious code on the affected systems remotely. This security vulnerability has been assigned the identifier CVE-2023-41056.

This blog post will detail the vulnerability, how it can be exploited, and how to secure your Redis installation against it. We will also include code snippets and references to original sources for a better understanding of this issue.

Description of CVE-2023-41056

CVE-2023-41056 revolves around Redis's incorrect handling of memory buffers resizing, resulting in an integer overflow, which can then lead to heap overflow and potential remote code execution. This issue has been addressed in the following versions of Redis:

7.2.4

Users are strongly encouraged to update their Redis installations to these patched versions to protect their systems from exploitation.

Exploiting the Vulnerability

Attackers looking to exploit this vulnerability would typically start by sending specially crafted data packets to the target Redis server. These packets could trick the server into triggering the memory buffer resizing and causing an integer overflow, which would then lead to a heap overflow. A malicious attacker may then be able to leverage this overflow to execute arbitrary code on the affected Redis server remotely.

While the specifics of the exploit vary depending on the attacker's approach and target environment, here's a code snippet that demonstrates how the buffer resizing error could be triggered:

def trigger_vulnerability(redis_conn):
    oversized_payload = b"A" * xFFFFFFFF

    try:
        redis_conn.set("vuln_trigger", oversized_payload)
    except Exception as e:
        print("Error triggering the vulnerability:", str(e))

# Connect to the Redis server and trigger the vulnerability
import redis
redis_conn = redis.StrictRedis(host="target_redis_server", port=6379)
trigger_vulnerability(redis_conn)

This example assumes a connection to a vulnerable Redis server and sends an oversized payload to trigger the memory buffer resizing bug. Please note that this example is for illustration purposes only and should not be used for malicious purposes.

1. Update Redis: Ensure that you have updated your Redis installation to the latest patched version (7..15 or 7.2.4) to fix the vulnerability. You can obtain the updated packages from the official Redis website (https://redis.io/download) or through your distribution package manager.

2. Disable Unsafe Commands: As a general security practice, you should disable potentially unsafe Redis commands (such as DEBUG and FLUSHALL) that can be used maliciously by attackers. You can disable these commands by modifying your Redis configuration file and adding the following line:

`

3. Enable Authentication: To prevent unauthorized access to your Redis server, enable authentication by setting a strong password in your Redis configuration file:

`

4. Implement Network Security: Properly restrict access to your Redis server by implementing firewall rules and security group policies, ensuring that only trusted IP addresses can communicate with the Redis server.

Conclusion

CVE-2023-41056 represents a significant security risk to Redis installations, as it allows attackers the potential for remote code execution through a memory buffer resizing bug. By understanding the vulnerability, its exploitation, and the necessary steps to secure your Redis installation, you can mitigate the risks posed by this issue and help protect your servers and infrastructure from malicious attacks.

Original references for further reading

- Redis Security
- Redis Security Advisory CVE-2023-41056

Timeline

Published on: 01/10/2024 16:15:46 UTC
Last modified on: 01/22/2024 18:58:13 UTC