PILOS Cross-Origin Resource Sharing Misconfiguration Vulnerability

A Cross-Origin Resource Sharing (CORS) misconfiguration vulnerability has been identified in PILOS versions prior to 4.8.0. The issue arises because the application reflects the 'Origin' request header in the 'Access-Control-Allow-Origin' response header without proper validation or whitelisting. Additionally, 'Access-Control-Allow-Credentials' is set to true. This misconfiguration could allow a malicious website on a different origin to send requests, including credentials, to the PILOS API. If the server accepts these cross-origin requests as authenticated, it may enable the exfiltration of data or actions using the victim's credentials. However, due to Laravel's session handling, which applies additional origin checks, this vulnerability is not believed to be exploitable in typical PILOS deployments.

Impact

Exploitation could lead to unauthorized actions or data exfiltration using the victim's credentials, but this vulnerability is not considered exploitable in standard PILOS deployments.

Reproduction

The vulnerability can be reproduced by sending a cross-origin request to the PILOS API from a malicious website. The 'Origin' header should be set to a different origin than the PILOS application. The response can be checked for the 'Access-Control-Allow-Origin' header to see if the origin was reflected without validation.

Remediation

Users can update to PILOS version 4.8.0 or later, where this vulnerability has been patched. If using an earlier version, remove CORS headers in the reverse proxy configuration. For NGINX, add 'proxy_hide_header Access-Control-Allow-Origin;' and 'proxy_hide_header Access-Control-Allow-Credentials;'. For Apache, use 'Header unset Access-Control-Allow-Origin' and 'Header unset Access-Control-Allow-Credentials'.