CVE-2015-2171 in Slim
Summary
by MITRE
Middleware/SessionCookie.php in Slim before 2.6.0 allows remote attackers to conduct PHP object injection attacks and execute arbitrary PHP code via crafted session data.
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Analysis
by VulDB Data Team • 05/02/2022
The vulnerability identified as CVE-2015-2171 resides within the Slim PHP microframework's session cookie handling mechanism, specifically in the Middleware/SessionCookie.php file. This flaw represents a critical security weakness that enables remote attackers to perform PHP object injection attacks, ultimately allowing arbitrary code execution on affected systems. The vulnerability affects Slim versions prior to 2.6.0, making it a significant concern for applications that rely on this popular web framework for building RESTful APIs and web applications. The issue stems from insufficient input validation and sanitization of session data, which is processed without proper security measures to prevent malicious object deserialization.
The technical implementation of this vulnerability occurs when the Slim framework deserializes session data without adequate security checks, allowing attackers to inject malicious PHP objects into the session storage. When the framework processes these crafted session cookies, it automatically deserializes the data, triggering the execution of malicious code contained within the injected objects. This type of vulnerability falls under the CWE-502 category, specifically CWE-502 Deserialization of Untrusted Data, which is a well-documented weakness in software security that enables attackers to execute arbitrary code through maliciously crafted serialized data. The attack vector exploits the framework's trust in session data without proper validation, creating a pathway for privilege escalation and system compromise.
The operational impact of CVE-2015-2171 extends beyond simple code execution, as it provides attackers with the ability to manipulate application behavior, access sensitive data, and potentially gain full control over affected systems. Remote attackers can leverage this vulnerability to execute commands on the server, read or modify application data, and establish persistent access through the compromised session handling mechanism. The implications are particularly severe for web applications that store sensitive information in sessions or rely on session data for authentication and authorization decisions. This vulnerability directly maps to several techniques documented in the MITRE ATT&CK framework under the T1059.007 sub-technique for Command and Scripting Interpreter: PHP, and T1566.001 for Phishing: Spearphishing Attachment, as attackers can use this vulnerability to execute malicious PHP payloads and maintain persistence within target environments.
Mitigation strategies for CVE-2015-2171 primarily involve upgrading to Slim framework version 2.6.0 or later, where the session cookie handling has been properly secured against object injection attacks. Organizations should also implement additional security measures including input validation for session data, regular security audits of session handling mechanisms, and monitoring for suspicious session activity. The implementation of secure session management practices such as using secure session identifiers, implementing proper session expiration policies, and employing encryption for session data transmission can significantly reduce the risk of exploitation. Additionally, organizations should consider implementing web application firewalls and intrusion detection systems to monitor for potential exploitation attempts, while following the principle of least privilege to limit the potential damage from successful attacks. Regular security training for development teams on secure coding practices and proper session management techniques remains essential for preventing similar vulnerabilities in future applications.