CVE-2021-3818 in grav
Summary
by MITRE • 09/27/2021
grav is vulnerable to Reliance on Cookies without Validation and Integrity Checking
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Analysis
by VulDB Data Team • 10/02/2021
The vulnerability identified as CVE-2021-3818 affects the grav content management system and represents a critical security flaw related to cookie handling mechanisms. This issue stems from the application's reliance on cookies for session management without implementing proper validation and integrity checking measures. The grav platform, which is built on php and designed for modern web publishing, utilizes cookies to maintain user sessions and track authentication status across multiple requests. However, the absence of cryptographic integrity checks on these cookies creates a significant attack surface that adversaries can exploit to manipulate session states and gain unauthorized access to user accounts.
The technical nature of this vulnerability aligns with CWE-614, which specifically addresses the issue of relying on cookies without sufficient validation and integrity checking. When grav systems process authentication cookies, they fail to implement proper cryptographic signatures or checksums that would verify the cookie's origin and integrity. This weakness allows attackers to craft malicious cookies that appear legitimate to the system, potentially enabling session hijacking attacks where unauthorized users can impersonate legitimate authenticated users. The vulnerability exists at the application layer and affects the authentication and session management components of the grav platform, making it particularly dangerous as it directly impacts the core security mechanisms that protect user accounts and sensitive data.
The operational impact of CVE-2021-3818 extends beyond simple unauthorized access to encompass potential data breaches, privilege escalation, and complete system compromise. Attackers leveraging this vulnerability can manipulate user sessions to perform actions they would not normally be authorized to execute, potentially leading to data modification, deletion, or exposure of confidential information. The vulnerability affects all versions of grav that rely on cookie-based authentication without proper integrity validation, making it a widespread concern across numerous installations. Organizations using grav for content management, particularly those handling sensitive data or requiring user authentication, face significant risk of unauthorized access and potential regulatory compliance violations.
Mitigation strategies for CVE-2021-3818 should focus on implementing proper cookie validation and integrity checking mechanisms throughout the grav platform. Security measures include enabling secure cookie attributes such as HttpOnly, Secure, and SameSite flags to prevent cross-site scripting attacks and session hijacking attempts. Organizations should also implement cryptographic signatures or HMAC (Hash-based Message Authentication Code) for cookie validation to ensure that cookies have not been tampered with during transmission. The recommended approach involves upgrading to patched versions of grav that address this vulnerability through proper cookie integrity checking implementations. Additionally, implementing additional authentication layers such as multi-factor authentication and monitoring for suspicious authentication patterns can provide defense-in-depth against potential exploitation attempts. Security professionals should also consider implementing web application firewalls to detect and block suspicious cookie manipulation attempts, while ensuring that all cookie-based session management components are properly validated against known good values before being accepted by the application.
The vulnerability demonstrates the critical importance of proper session management practices in web applications and aligns with ATT&CK technique T1548.002 which covers privilege escalation through session management weaknesses. Organizations should conduct comprehensive security assessments of their grav installations to identify all cookie-based authentication mechanisms and ensure they implement proper cryptographic validation. Regular security audits and penetration testing should include verification of cookie integrity checking implementations to prevent similar vulnerabilities from being introduced in future updates or custom modifications to the grav platform.