In early 2022, Microsoft disclosed several critical vulnerabilities in its Windows operating system. One of the most concerning of them is CVE-2022-24492, which is a flaw in the Remote Procedure Call (RPC) Runtime. This vulnerability could let attackers run code on a victim’s computer remotely, with the same rights as the RPC service. In this long-read, we’ll break down what this means, how the vulnerability can be exploited, what’s unique about this CVE, and what you can do to protect your systems.
What is CVE-2022-24492?
CVE-2022-24492 is a Remote Code Execution (RCE) vulnerability found in the Windows RPC Runtime. The RPC service helps different programs and services communicate over the network or within a local machine. RPC is essential for many core Windows functions, which makes vulnerabilities here particularly dangerous.
This CVE is unique and distinct from other RPC bugs such as CVE-2022-24528 and CVE-2022-26809.
User Interaction Required: None
- Patch Available? Yes (see Microsoft Security Guide)
The Heart of the Problem
The vulnerability lies in how the Windows RPC runtime component parses network requests. An attacker can send specially crafted data to vulnerable RPC services, causing them to execute attacker-controlled code.
Attack Scenario
- An attacker finds a Windows machine with the RPC service exposed (usually port 135, but can also be 139/445).
This message is sent over the network to the vulnerable machine.
- If the machine is unpatched, it processes the malicious request and ends up running malicious code as the RpcSs service (often as SYSTEM).
Simple Exploit Example *(For Education Purposes Only!)*
Below is a pseudo-Python code snippet that shows how an attacker might interact with a vulnerable RPC server.
import socket
# Windows RPC usually listens on port 135
RPC_SERVER_IP = "192.168.1.100"
RPC_PORT = 135
# Craft a malicious payload (highly simplified for demonstration)
malicious_rpc_request = b"\x05\x00\xb\x03..." # Real exploit uses complex DCE/RPC format
# Connect to the RPC server
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.connect((RPC_SERVER_IP, RPC_PORT))
s.send(malicious_rpc_request)
# If vulnerable, the server may now execute attacker's code
s.close()
> In reality, working exploits are much more complicated, using detailed DCE/RPC framing based on reverse engineering. See MSRPC documentation.
Metasploit
As of this writing, public, reliable Metasploit modules for CVE-2022-24492 are not widely available—likely due to the high complexity and risk of crashing target services during testing.
CVE-2022-24492 is not the same as
- CVE-2022-26809: Also targets RPC on port 135 but uses different attack paths and vulnerable code sections.
CVE-2022-24528: Involves a different class of bugs with another attack pattern.
All three, however, can be chained for network attacks against Windows systems. Patching all is recommended.
Microsoft Guidance:
Rapid7 Research:
Analysis of Recent Windows RPC Vulnerabilities
MSRPC Protocol Documentation:
Microsoft Open Specifications - RPC
Root.cz Write-up:
RPC RCE vulnerabilities in 2022
How to Protect Your System
- Apply Microsoft Patches: Download and install the latest updates from Windows Update or the Microsoft Security Update Guide.
- Block RPC Ports Externally: Use firewalls to block ports 135, 139, and 445 from public access whenever possible.
Least Privilege: Limit services running as SYSTEM or other high-privilege accounts.
- Audit Exposure: Only allow necessary devices to be accessible on internal networks. Remove legacy software where possible.
Conclusion
CVE-2022-24492 is a critical vulnerability that affects all unpatched Windows installations running the RPC service. If you’re managing Windows systems—whether at work or at home—patch as soon as possible, audit your exposed services, and monitor for suspicious network activity. Failing to address this flaw could allow remote, unauthenticated attackers to completely compromise your computers.
Stay safe. Patch early. Audit regularly.
*If you found this breakdown useful, please share it with your colleagues or team. For in-depth technical details, follow the official Microsoft advisory and professional security researchers linked above.*
Timeline
Published on: 04/15/2022 19:15:00 UTC
Last modified on: 04/19/2022 17:31:00 UTC