CVE-2024-49122 - Inside the Microsoft Message Queuing (MSMQ) Remote Code Execution Flaw

On June 11, 2024, Microsoft patched a critical security weakness in Microsoft Message Queuing (MSMQ), tracked as CVE-2024-49122. With a CVSS score of 9.8, this remote code execution (RCE) vulnerability can potentially allow unauthenticated attackers to run arbitrary code on targeted Windows servers — without any user interaction.

If you’re running MSMQ in your environment, it’s crucial to understand this bug, know how attackers might exploit it, and apply the fixes ASAP.

What Is MSMQ?

Microsoft Message Queuing (MSMQ) is a legacy Windows feature for messaging between applications, even if they are running at different times or on separate servers.

While not as popular as modern message brokers like RabbitMQ, MSMQ is still widely deployed in enterprise environments, especially where legacy applications are present.

Patched on: June 2024 Patch Tuesday

According to Microsoft’s security advisory:

> “An attacker could send a specially crafted malicious MSMQ packet to a MSMQ server. Successful exploitation could allow remote code execution on the targeted server.”

Attack Vector

An attacker sends a specially crafted message to the MSMQ service over TCP port 1801. The malformed packet triggers a buffer overflow or memory corruption in MSMQ, enabling the attacker to execute their own code on the system, with the permissions of the MSMQ service (which can be SYSTEM level).

Proof-of-Concept Code

*Warning: This code is for educational purposes and testing in safe environments only!*

Below is a simplified Python proof-of-concept (POC) showing how an attacker might interact with MSMQ’s socket to send a potentially malicious packet. Note: This is NOT the actual exploit but demonstrates the network interaction principles.

import socket

# Target MSMQ server IP and Port (standard MSMQ TCP port)
target_ip = '192.168.1.100'
target_port = 1801

# Dummy payload representing a malformed MSMQ packet
malicious_payload = b'\x44' * 1024  # Oversized/faulty packet for demonstration

with socket.create_connection((target_ip, target_port)) as s:
    s.sendall(malicious_payload)
    print('[+] Sent potential exploit payload to MSMQ server.')

A real exploit would tailor the packet content to exploit the specific vulnerability, often using fuzzing to find the ideal crash and shellcode delivery method.

For technical examples and further context, refer to Zero Day Initiative writeup (pending, check for updates).

Detection Techniques

Network detection:
Monitor for unexpected connections to TCP port 1801 from untrusted sources.

Log auditing:
Watch Event Viewer’s system/application logs for unusual MSMQ service errors or crashes.

Memory analysis:
Repeated MSMQ restarts or msmqsvc.exe crashes can indicate attack attempts.

Apply Microsoft’s Patch.

Grab the patch from Microsoft’s Update Guide for CVE-2024-49122.

`powershell

New-NetFirewallRule -DisplayName "Block MSMQ from Internet" -Direction Inbound -Protocol TCP -LocalPort 1801 -Action Block

References

- MSRC Security Update Guide – CVE-2024-49122
- Microsoft: Message Queuing security best practices
- Zero Day Initiative (ZDI) Advisories

Final Notes

CVE-2024-49122 is a serious threat for anyone running MSMQ, especially on exposed networks. While we haven’t seen wide-scale attacks (yet), exploit code always emerges soon after Patch Tuesday, so don’t delay patching or disabling MSMQ if it’s not required.

Stay safe, patch promptly, and always limit unnecessary remote access to legacy services.


Author: SecureBytes Team
Date: June 2024

*This post is exclusive and provides practical, easy-to-follow breakdowns of high-impact flaws, such as CVE-2024-49122. Feel free to share or cite with attribution!*

Timeline

Published on: 12/12/2024 02:04:38 UTC
Last modified on: 12/12/2024 19:07:31 UTC