CVE-2008-5840 in phpicalendar
Summary
by MITRE
PHP iCalendar 2.24 and earlier allows remote attackers to bypass authentication by setting the phpicalendar and phpicalendar_login cookies to 1.
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Analysis
by VulDB Data Team • 11/04/2024
The vulnerability identified as CVE-2008-5840 affects PHP iCalendar version 2.24 and earlier, representing a critical authentication bypass flaw that undermines the security posture of web applications relying on this calendar management system. This issue stems from insufficient validation of authentication state within the application's cookie handling mechanism, allowing malicious actors to gain unauthorized access to protected calendar functionalities without proper credentials. The vulnerability specifically targets the authentication flow by exploiting the application's trust in cookie values, particularly those related to calendar display and login status.
The technical implementation of this flaw resides in the application's session management and authentication verification logic. When PHP iCalendar processes user requests, it checks for specific cookie values to determine whether a user should be granted access to calendar features. By setting the phpicalendar and phpicalendar_login cookies to the value of 1, attackers can manipulate the application's internal state to bypass the normal authentication process. This cookie manipulation effectively tricks the application into believing that a valid user session exists, thereby granting access to calendar data and administrative functions that should otherwise be restricted to authenticated users.
The operational impact of this vulnerability extends beyond simple unauthorized access, as it creates a persistent security risk that can be exploited repeatedly by attackers. Once compromised, the affected system allows unauthorized users to view, modify, or delete calendar entries, potentially exposing sensitive scheduling information or enabling further attacks through the calendar interface. This authentication bypass can be executed remotely without requiring any prior knowledge of valid credentials, making it particularly dangerous in environments where calendar systems contain confidential information such as meeting schedules, project timelines, or personal appointments. The vulnerability also aligns with attack patterns described in the MITRE ATT&CK framework under credential access and privilege escalation techniques, as it allows attackers to assume legitimate user identities without proper authentication.
The root cause of this vulnerability maps directly to CWE-287, which addresses improper handling of authentication tokens, and CWE-306, which covers missing authentication checks. These weaknesses in the application's security architecture demonstrate a failure to properly implement authentication controls and validate user credentials before granting access to protected resources. Organizations using affected versions of PHP iCalendar should immediately implement mitigations including upgrading to a patched version, implementing additional authentication layers, or disabling the vulnerable cookie-based authentication mechanism. The vulnerability also highlights the importance of proper input validation and authentication state management in web applications, emphasizing that cookie values should never be trusted without proper verification and that authentication checks must be performed consistently throughout the application's request processing cycle.