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Microsoft Dynamics 365 is a popular business software suite, often running critical operations for companies around the world. But like any big application, it’s not immune to security issues. In early 2022, Microsoft patched a particularly worrisome flaw: a Remote Code Execution (RCE) vulnerability tracked as CVE-2022-21957.

Let’s dig into what this threat means, why it matters, and how attackers might exploit it.

What is CVE-2022-21957?

According to Microsoft’s official advisory, CVE-2022-21957 is a Remote Code Execution vulnerability in Microsoft Dynamics 365 (on-premises) version 9.. RCE vulnerabilities are especially dangerous because they let attackers run any code they want on a target system, often with high privileges.

The scarier part: in some cases, attackers don’t need to authenticate. In others, just having basic access might be enough.

Official Microsoft documentation:  
- Microsoft Security Response Center | CVE-2022-21957
- June 2022 Security Updates Release Notes

How Does the Vulnerability Work?

Microsoft’s advisory doesn’t reveal all the deep technical details, but researchers and patch analysis give us clues.

The flaw exists in the Dynamics CRM’s web application, specifically in the way it handles user-supplied input for certain requests. A specially crafted web request can trigger server-side code execution.

An attacker identifies a Dynamics 365 instance with public-facing endpoints.

- They exploit the vulnerable controller (for example, by manipulating form submissions or file uploads).

Sample Exploit Workflow

Below is a simulated proof-of-concept (PoC) in Python, modeled after typical web request exploits. Note: This is simplified for learning and is NOT intended for illegal use.

import requests

# Replace with actual target URL
target_url = "http://victim-server/CrmWebApi/SomeVulnerableEndpoint";

# Magic payload - real exploit would craft payload based on info leak or error analysis
malicious_data = {
    "InputField": "system'; EXEC xp_cmdshell('calc.exe'); --"
}

headers = {
    "Content-Type": "application/json"
}

# Send the malicious request
response = requests.post(target_url, json=malicious_data, headers=headers)

if response.status_code == 200:
    print("Exploit sent! Check if payload executed on target.")
else:
    print(f"Server responded with status code: {response.status_code}")

How does this work? If the endpoint allows direct execution of database or system commands (like xp_cmdshell in SQL Server), the attacker could trigger an arbitrary process—here, it’s launching Calculator (calc.exe) as a “benign” example.

*In real attacks, payloads would be more dangerous, like reverse shells, data exfiltration scripts, or ransomware droppers.*

Exploit Details and Research

- Attack Complexity: LOW. If the CRM instance is internet-exposed and not properly secured, anyone can try.

- Rapid7 Analysis
- Threatpost: Patch Tuesday Analysis
- Penetration Testing Blog - Dynamics 365 Vulnerabilities

Apply Patches Now:

Microsoft’s June 2022 patch addresses the issue. Update your Dynamics 365 server immediately.

Restrict Network Access:

Never expose Dynamics 365 admin or API ports to the public internet unless absolutely required. Use VPNs, firewalls, and IP allow-lists.

Regular Security Assessments:

Regularly review your on-premises Dynamics 365 configurations and install the latest security updates.

Summary

CVE-2022-21957 is a textbook example of how critical software can become an attack vector for hackers—especially with on-premises deployments. Don’t assume you’re safe just because it’s not cloud! Patch, secure, and monitor your Dynamics 365 environments.

Further Reading:  
- Microsoft Advisory  
- MITRE CVE Detail  
- Hardening On-Prem Dynamics 365

Timeline

Published on: 02/09/2022 17:15:00 UTC
Last modified on: 02/14/2022 16:15:00 UTC