Recently, Oracle revealed CVE-2024-21247: a vulnerability in the MySQL Client, specifically in the mysqldump component. While its CVSS score (3.8) isn't extreme, this bug opens the door for high-privileged attackers with network access to read and change data that is supposed to be beyond their reach, by targeting clients during backup or migration operations.

This post will break down how the issue works, show the kinds of risks it creates, give practical code snippets and attack scenarios, and showcase how you can check if you're vulnerable. Read on for an exclusive, easy-to-understand analysis.

What is CVE-2024-21247?

CVE-2024-21247 is an easily exploitable vulnerability found in the mysqldump tool bundled with  Oracle MySQL. It affects:

9..1 and prior

The issue sits in the client component, so it only affects those using the client tools -- not the server itself.

Short Summary and Impact

A clever attacker with high-level access and network connectivity can craft responses or manipulate queries during mysqldump operations. This could let them:

Insert, update, or delete (I:L) data in the MySQL database via the client tool

While full system compromise is unlikely, the ability to steal or change database records as part of backup, migration, or diagnostic processes is a real risk in multi-user or multi-tenant environments.

How Does the Exploit Work?

At its core, the vulnerability likely involves the way mysqldump interacts with the server using certain protocols (like MySQL native or X Protocol). If the tool doesn't properly validate server responses or separates the export logic poorly, it may end up fetching or modifying data it shouldn't.

A malicious (or compromised) server could slip unauthorized data or commands to the client. For example, if an attacker can manipulate the server or network, they can send crafted information that fools mysqldump into running destructive or information-leaking operations.

Runs mysqldump from an *untrusted* or compromised network.

3. The server (or a man-in-the-middle, if the connection isn’t encrypted) injects data or commands into the dump stream.

Practical Example: Exploiting mysqldump

Suppose a company has a poorly managed backup automation. A script runs as root, using a privileged DBA user.

mysqldump -u root -p'MySecret!' --all-databases --host=prod-db.internal > backup.sql

If network traffic is not encrypted (--ssl-mode=DISABLED is default in some old scripts), an attacker who hijacks DNS, ARP, or routes may inject a *malicious MySQL server* at prod-db.internal. On connecting, this rogue server crafts a response that:

Leaked Data:

- Returns extra rows or tables from restricted databases, including ones the user shouldn't see (e.g., mysql.user).

Unauthorized Modify:

- Injects SQL statements in the dump or causes the client to process unexpected data as valid, possibly leading to updates or deletions on next restore.

Illustrative Rogue Server Python (for Learning Only)

You can use frameworks like Impacket to create a fake MySQL server:

from impacket.examples import mssqlclient

# Replace with your own code for a fake MySQL server
# When client connects, return a custom response with injected rows

def handle_connection(client):
    # ... handshake ...
    # send extra rows from forbidden tables
    # or craft overflow binary packets

# For educational use only. Never attack systems you don't own!

This simulation will show the dump tool leaking or replaying info it wasn't supposed to access.

- Oracle Critical Patch Advisory - CVE-2024-21247
- NVD page for CVE-2024-21247
- MySQL Release Notes

Check your installed version

mysqldump --version
# or
mysql --version

If it's 8..39 or older, 8.4.2 or older, or 9..1 or older, update immediately.

Upgrade Now: Patch to the latest MySQL Client as soon as possible. This is the only full fix.

2. Encrypt Connections: Always use --ssl-mode=REQUIRED when connecting over networks, especially in production.
3. Limit Use of High-Privileged Accounts: Avoid running backups or diagnostic jobs with unnecessarily privileged accounts, especially over networks.

Conclusion

CVE-2024-21247 may seem minor at first glance, but for busy DBAs who rely on consistent, trustworthy database exports, it is a reminder that client security matters as much as server security. If you automate with mysqldump, patch promptly, encrypt everything, and treat your database credentials as precious. Attackers who gain even a high privilege user on a misconfigured network can use bugs like this for exfiltration or subtle sabotage.

Stay current. Patch often. Audit your automation.

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Timeline

Published on: 10/15/2024 20:15:14 UTC
Last modified on: 10/16/2024 20:33:33 UTC