CVE-2024-26253 - How Attackers Can Exploit Windows rndismp6.sys for Remote Code Execution (RCE)

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Microsoft has recently patched a serious vulnerability tracked as CVE-2024-26253 in the Windows driver called rndismp6.sys. This driver helps Windows communicate with USB and network devices using the RNDIS (Remote Network Driver Interface Specification) protocol, which is common for tethering and other device networking. In this post, we'll break down what the vulnerability is, how it works, and what attackers could potentially do if your system is unpatched. We'll also show code snippets and share links to references and the official advisory.

What is CVE-2024-26253?

CVE-2024-26253 is a Remote Code Execution (RCE) vulnerability in Windows. It affects the rndismp6.sys driver, found in modern Windows editions. An attacker who successfully exploits it can execute code in the context of the kernel, which means full control of your PC.

Microsoft's summary:
> *“A remote, unauthenticated attacker could use this vulnerability to run arbitrary code on the target system via crafted network packets that interact with the affected driver.”*

Windows Server 2022

(For a full list, see the Microsoft advisory)

How Does the Vulnerability Work?

rndismp6.sys is responsible for handling RNDIS communication. The bug is in the way rndismp6 parses certain packets. A specially crafted RNDIS packet can trigger a heap buffer overflow or similar memory corruption. Since rndismp6 runs in kernel mode, successful exploitation leads to full system compromise or potentially a BSOD (blue screen).

Imagine plugging in a USB device that pretends to be a network card—if that device feeds your PC this malicious packet, your computer could be taken over without further input.

Example Code Snippet (Proof of Concept)

While we avoid sharing fully weaponized exploits, here's a simplified Python example of how an attacker might use a USB gadget (like a Raspberry Pi Zero with USB OTG) to target a Windows machine with a bad RNDIS packet:

# This is a conceptual PoC for educational purposes only!
from scapy.all import *

# Create an RNDIS-like malformed packet that triggers the bug
packet = Raw(load=b"\x00"*200 + b"\xDE\xAD\xBE\xEF")  # Oversized payload

# Send packet over RNDIS interface (not functional in scapy; real exploit would use raw USB gadget)
sendp(packet, iface="usb")

Note: Real exploits would need deep knowledge of the RNDIS protocol and Windows kernel structures, but this illustrates the general mechanism: abuse Windows USB networking with malformed data.

The device sends a specially crafted packet purposely designed to exploit the parsing bug.

4. The malicious code executes in kernel mode, giving root/admin privileges.

Potential outcomes:

How Serious Is It?

- Attack vector: Local (plugged in USB), but some scenarios may allow remote attacks via network protocols and virtual environments.

Mitigation & Suggestions

Patch Immediately!

Microsoft released a fix in the June 2024 Patch Tuesday.

- Official Microsoft Advisory and Updates

Final Thoughts

CVE-2024-26253 shows how even everyday drivers like rndismp6.sys can hide dangerous bugs with severe consequences. If you manage Windows devices—even at home—patch right away and stay alert for suspicious USB/network activity. Always verify what you connect to your devices!

Timeline

Published on: 04/09/2024 17:15:46 UTC
Last modified on: 04/10/2024 13:24:00 UTC