CVE-2020-28482 in fastify-csrf Package
Summary
by MITRE • 01/19/2021
This affects the package fastify-csrf before 3.0.0. 1. The generated cookie used insecure defaults, and did not have the httpOnly flag on: cookieOpts: { path: '/', sameSite: true } 2. The CSRF token was available in the GET query parameter
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Analysis
by VulDB Data Team • 02/15/2021
The vulnerability identified as CVE-2020-28482 impacts the fastify-csrf package version prior to 3.0.0, representing a critical security flaw that undermines the protection mechanisms designed to prevent cross-site request forgery attacks. This package serves as a middleware component for the fastify web framework, implementing csrf token validation to protect applications from malicious requests that could exploit user sessions. The vulnerability stems from two distinct but related implementation flaws that together create a significant attack surface for adversaries seeking to compromise application security.
The first technical flaw involves the insecure default configuration of the cookie generation mechanism, specifically the absence of the httpOnly flag in the cookie options. The vulnerable configuration cookieOpts: { path: '/', sameSite: true } demonstrates a critical misconfiguration that leaves the csrf token cookie susceptible to cross-site scripting attacks. Without the httpOnly flag, the cookie becomes accessible through client-side javascript execution, enabling attackers to extract the csrf token from the browser's cookie storage. This directly violates security best practices and aligns with CWE-1004 which addresses insecure cookie attributes that could lead to session hijacking and token theft. The sameSite attribute alone is insufficient to protect against all attack vectors, particularly when combined with the lack of httpOnly protection.
The second vulnerability occurs when csrf tokens are transmitted through GET query parameters rather than being properly secured within request headers or POST body data. This design flaw allows csrf tokens to be exposed in browser history, server logs, and referrer headers, creating multiple attack vectors for malicious actors. When tokens appear in query strings, they become visible to anyone who can observe network traffic or access web server logs, significantly reducing their effectiveness as security controls. This implementation directly contradicts established security guidelines for csrf token handling and represents a violation of CWE-312 which addresses the exposure of sensitive data through improper data handling.
The operational impact of this vulnerability extends beyond simple token exposure, as it creates multiple pathways for attackers to exploit applications protected by the fastify-csrf middleware. An attacker could leverage the insecure cookie configuration to steal csrf tokens through javascript-based attacks, then use those tokens to forge authenticated requests against vulnerable applications. The combination of exposed tokens in query parameters and insecure cookie attributes creates a particularly dangerous scenario where attackers can bypass csrf protection entirely. This vulnerability affects the fundamental security model of the middleware, potentially allowing attackers to perform unauthorized actions on behalf of authenticated users.
Mitigation strategies for CVE-2020-28482 require immediate attention to address both identified flaws in the fastify-csrf package. The primary recommendation involves upgrading to version 3.0.0 or later, which implements proper cookie security configurations including the httpOnly flag and removes the insecure default settings. Organizations should also review their application code to ensure csrf tokens are not being passed through query parameters and instead utilize secure methods such as request headers or POST data. Security teams must implement comprehensive monitoring of application logs to detect any potential exploitation attempts involving csrf tokens. The remediation process should include thorough security testing of all applications using this middleware to verify that proper csrf protection mechanisms are now in place. Additionally, organizations should consider implementing additional security layers such as content security policies and strict header configurations to further protect against exploitation attempts. The vulnerability serves as a reminder of the critical importance of secure cookie handling and proper token management in web application security frameworks, aligning with ATT&CK technique T1548.002 which covers privilege escalation through cookie manipulation and T1071.004 which addresses protocol tunneling through insecure data transmission methods.