CVE-2019-16751 in Devise Token Auth
Summary
by MITRE
An issue was discovered in Devise Token Auth through 1.1.2. The omniauth failure endpoint is vulnerable to Reflected Cross Site Scripting (XSS) through the message parameter. Unauthenticated attackers can craft a URL that executes a malicious JavaScript payload in the victim's browser. This affects the fallback_render method in the omniauth callbacks controller.
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Analysis
by VulDB Data Team • 12/27/2023
The vulnerability identified as CVE-2019-16751 represents a critical reflected cross site scripting flaw within the Devise Token Auth gem version 1.1.2 and earlier. This issue specifically targets the omniauth failure endpoint, which serves as a critical component in the authentication flow for applications utilizing the devise_token_auth library. The vulnerability stems from improper input validation and sanitization of the message parameter within the fallback_render method of the omniauth callbacks controller. When an application using this gem encounters an omniauth authentication failure, it renders a response that directly incorporates user-supplied input from the message parameter without adequate sanitization, creating an avenue for malicious actors to inject and execute arbitrary javascript code within the victim's browser context.
The technical exploitation of this vulnerability occurs through the manipulation of the omniauth failure endpoint URL, where attackers can craft malicious URLs containing crafted javascript payloads within the message parameter. When victims navigate to these specially crafted URLs, the reflected XSS occurs because the application directly echoes the malicious input back to the user's browser without proper encoding or sanitization. This vulnerability falls under CWE-79, which specifically addresses Cross-Site Scripting flaws, and represents a classic reflected XSS attack vector that allows attackers to execute code in the victim's browser session. The impact is particularly severe because it affects unauthenticated attackers who can exploit this vulnerability without requiring any prior access or credentials, making it a significant threat to applications using the affected gem version.
The operational impact of this vulnerability extends beyond simple script execution, as it can lead to session hijacking, credential theft, and potential full system compromise if victims are authenticated users. Attackers can leverage this vulnerability to steal session cookies, redirect users to malicious sites, or perform actions on behalf of authenticated users within the application context. The flaw affects the fallback_render method in the omniauth callbacks controller, which means that any application using devise_token_auth that encounters authentication failures will be vulnerable to this attack. This vulnerability aligns with ATT&CK technique T1566, specifically the use of malicious links or URLs to execute malicious code in user browsers, and represents a significant risk to web application security. The vulnerability's exploitation is straightforward and requires minimal technical expertise, making it particularly dangerous in production environments where applications may not be properly monitoring or validating all input parameters.
Mitigation strategies for CVE-2019-16751 primarily involve upgrading to a patched version of the devise_token_auth gem, specifically version 1.1.3 or later, where the developers have implemented proper input sanitization and output encoding for the message parameter. Organizations should also implement comprehensive input validation and output encoding practices throughout their applications, particularly for any parameters that may be reflected back to users. Security teams should conduct thorough code reviews to identify similar patterns in other application components and ensure that all user-supplied input is properly sanitized before being rendered in web responses. Additionally, implementing content security policies and using web application firewalls can provide additional layers of protection against reflected XSS attacks, though these should not be considered replacements for proper input validation and sanitization. The vulnerability serves as a reminder of the critical importance of validating all user input and properly encoding output to prevent XSS attacks, particularly in authentication and authorization components where such vulnerabilities can have the most severe consequences.