Microsoft Azure Health Bot SSRF Vulnerability for Privilege Escalation

Overview

CVE-2025-21384 is a Server-Side Request Forgery (SSRF) vulnerability in Microsoft Azure Health Bot, allowing an authenticated attacker to send unauthorized requests from the server, potentially leading to privilege escalation within the network.

With a CVSS v3.1 score of 8.3 (HIGH), this vulnerability poses a significant risk to organizations using Azure Health Bot for healthcare automation and patient interactions.

Technical Details

Root Cause

The vulnerability arises due to improper validation of user-supplied URLs in HTTP requests processed by the Azure Health Bot service. An attacker can manipulate internal API calls, forcing the server to interact with internal services or cloud metadata endpoints, leading to:

Unauthorized access to internal systems
Retrieval of sensitive data (IAM credentials, configuration files)
Privilege escalation within Azure environments

Affected Versions

Microsoft Azure Health Bot versions prior to Hotfix Rollup 2025-03

Exploitation Scenario

Step 1: Attacker Gains Initial Access

An attacker first obtains valid credentials (e.g., through phishing, credential stuffing, or insider threats) to authenticate into the Azure Health Bot dashboard.

Step 2: Crafting a Malicious SSRF Payload

The attacker exploits a feature in the Health Bot that allows custom webhook integrations. Instead of a legitimate external API, they inject a malicious internal endpoint:

POST /api/webhooks/configure HTTP/1.1  
Host: healthbot.azurewebsites.net  
Authorization: Bearer [VALID_TOKEN]  
Content-Type: application/json  

{  
  "name": "Malicious_Webhook",  
  "url": "http://169.254.169.254/metadata/identity/oauth2/token?api-version=2025-03-30",  
  "events": ["patient_query"]  
}

Step 3: Azure Health Bot Fetches Internal Metadata

The server processes the request and retrieves Azure Instance Metadata Service (IMDS) data, including:

Temporary access tokens
IAM role credentials
Virtual network configurations

Step 4: Attacker Escalates Privileges

Using the stolen credentials, the attacker accesses Azure Resource Manager (ARM) API, granting them control over:

Virtual Machines
Storage Accounts
Key Vaults

Step 5: Lateral Movement & Data Exfiltration

With elevated privileges, the attacker moves laterally, extracting sensitive patient data or deploying ransomware.

Mitigation & Patch Information

Official Fix

Microsoft released a patch in March 2025. Organizations should:

Update Azure Health Bot to the latest version.
Restrict outbound requests from the bot to only whitelisted domains.
Implement network segmentation to block access to metadata services.

Workarounds (If Patching is Delayed)

Deploy Azure NSGs to block 169.254.169.254 from Health Bot instances.
Use Azure Policy to enforce input validation on webhook URLs.
Monitor anomalous outbound requests using Azure Sentinel.

Conclusion

CVE-2025-21384 demonstrates how SSRF in cloud services can lead to full cloud compromise. Organizations must prioritize patch management and least-privilege access controls to mitigate such risks.

References

https://nvd.nist.gov/

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Microsoft Azure Health Bot SSRF Vulnerability for Privilege Escalation