CVE-2015-8747 in Radicale
Summary
by MITRE
The multifilesystem storage backend in Radicale before 1.1 allows remote attackers to read or write to arbitrary files via a crafted component name.
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Analysis
by VulDB Data Team • 07/06/2022
The vulnerability identified as CVE-2015-8747 affects Radicale, an open-source calendar and contact server that implements the CalDAV and CardDAV protocols. This issue resides within the multifilesystem storage backend, which serves as the primary data persistence mechanism for the application. The flaw represents a critical path traversal vulnerability that allows remote attackers to bypass normal access controls and interact with arbitrary files on the underlying filesystem. The vulnerability specifically manifests when the application processes component names that contain malicious path traversal sequences, enabling unauthorized access to sensitive system files, configuration data, or other resources that should remain protected from external access.
The technical root cause of this vulnerability stems from insufficient input validation and sanitization within the multifilesystem storage backend implementation. When Radicale processes requests for calendar or contact data, it constructs filesystem paths based on the component names provided in the requests. The application fails to properly validate or sanitize these component names, allowing attackers to inject path traversal sequences such as ../ or ..\ that can navigate outside the intended storage directory. This weakness directly maps to CWE-22, which describes improper limitation of a pathname to a restricted directory, commonly known as path traversal or directory traversal attacks. The vulnerability enables attackers to read arbitrary files on the system, potentially exposing sensitive information such as configuration files, user data, or even system credentials that may be stored in accessible locations.
The operational impact of this vulnerability extends beyond simple data theft, as it can enable attackers to achieve arbitrary code execution or complete system compromise. Remote attackers can leverage this vulnerability to read sensitive files including but not limited to database connection strings, application configuration files, user credentials, or even system binaries that may be stored in predictable locations. The attack surface is particularly concerning because Radicale is often deployed in environments where it may have access to sensitive organizational data, including personal contact information, calendar entries, and other private communications. This vulnerability can be exploited by unauthenticated attackers who simply need to send crafted requests to the Radicale server, making it particularly dangerous in publicly accessible deployments. The implications align with ATT&CK technique T1083, which describes the discovery of system information through directory listing and file access activities.
Mitigation strategies for CVE-2015-8747 should focus on implementing proper input validation and sanitization within the multifilesystem storage backend. The most effective immediate solution involves implementing strict validation of component names to prevent path traversal sequences from being processed. Organizations should ensure that all component names are properly sanitized and validated before being used to construct filesystem paths. Additionally, implementing proper access controls and privilege separation is crucial, ensuring that the Radicale service operates with minimal required privileges and cannot access sensitive system directories. The application should be configured to use a dedicated, isolated storage directory with appropriate permissions that prevents access to system resources. Upgrading to Radicale version 1.1 or later is essential as this version includes the necessary patches that address the path traversal vulnerability. System administrators should also implement network-level controls such as firewalls to restrict access to Radicale services and monitor for suspicious access patterns that may indicate exploitation attempts. Regular security audits and penetration testing should be conducted to ensure that similar vulnerabilities are not present in other components of the application stack, as this type of weakness often indicates broader architectural issues that may require comprehensive security review.