CVE-2016-10549 in Sails
Summary
by MITRE
Sails is an MVC style framework for building realtime web applications. Version 0.12.7 and lower have an issue with the CORS configuration where the value of the origin header is reflected as the value for the Access-Control-Allow-Origin header. This would allow an attacker to make AJAX requests to vulnerable hosts through cross site scripting or a malicious HTML Document, effectively bypassing the Same Origin Policy. Note that this is only an issue when `allRoutes` is set to `true` and `origin` is set to `*` or left commented out in the sails CORS config file. The problem can be compounded when the cors `credentials` setting is not provided. At that point authenticated cross domain requests are possible.
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Analysis
by VulDB Data Team • 02/10/2020
The vulnerability described in CVE-2016-10549 affects the Sails JavaScript framework version 0.12.7 and earlier, presenting a critical cross-origin resource sharing (CORS) misconfiguration that fundamentally undermines web application security boundaries. This flaw manifests when the framework's CORS configuration permits unrestricted access by setting the origin header to an asterisk or leaving it commented out, combined with enabling allRoutes functionality. The core technical issue stems from the framework's improper handling of the Access-Control-Allow-Origin header, where it directly reflects the value of the incoming origin header without proper validation or sanitization. This behavior creates a dangerous condition where malicious actors can manipulate the origin header to gain unauthorized access to resources that should be protected by the same-origin policy.
The operational impact of this vulnerability extends beyond simple data exposure, as it enables sophisticated attack vectors through cross-site scripting (XSS) exploitation or malicious HTML document delivery. When attackers can control the origin header value, they effectively bypass the fundamental security mechanism that prevents unauthorized domains from making requests to protected resources. The vulnerability becomes particularly dangerous when combined with the absence of explicit credentials configuration in the CORS settings, as this allows for authenticated cross-domain requests to be executed without proper authorization checks. This creates a scenario where attackers can perform actions on behalf of authenticated users across different domains, potentially leading to session hijacking, data theft, or privilege escalation attacks. The issue is specifically tied to the framework's configuration where allRoutes is enabled, which means the vulnerability affects all routes within the application rather than being limited to specific endpoints.
From a cybersecurity perspective, this vulnerability aligns with CWE-346 (Origin Validation Error) and represents a classic case of insecure cross-origin resource sharing implementation. The flaw demonstrates how configuration errors in web application frameworks can create exploitable conditions that bypass fundamental security controls. The ATT&CK framework categorizes this as a technique involving web application attacks and specifically relates to the use of cross-origin resource sharing for privilege escalation and data exfiltration. Organizations using Sails framework versions prior to 0.12.8 should immediately implement mitigations including proper CORS configuration with specific origin validation, disabling allRoutes when not required, and explicitly setting credentials parameters to prevent unauthorized cross-domain requests. The vulnerability serves as a critical reminder of the importance of proper CORS configuration and the potential consequences of leaving security settings at default or overly permissive values, particularly in frameworks that handle sensitive data and authentication mechanisms.