CVE-2015-2308 in Symfony
Summary
by MITRE
Eval injection vulnerability in the HttpCache class in HttpKernel in Symfony 2.x before 2.3.27, 2.4.x and 2.5.x before 2.5.11, and 2.6.x before 2.6.6 allows remote attackers to execute arbitrary PHP code via a language="php" attribute of a SCRIPT element.
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Analysis
by VulDB Data Team • 06/14/2018
The CVE-2015-2308 vulnerability represents a critical server-side code execution flaw within the Symfony web application framework's HttpKernel component. This vulnerability specifically affects Symfony versions prior to the mentioned patched releases, creating a dangerous attack surface that allows remote adversaries to inject and execute arbitrary PHP code on affected servers. The flaw exists within the HttpCache class, which is responsible for handling HTTP caching mechanisms in Symfony applications, making it a particularly insidious vulnerability as it operates at a fundamental level of the framework's caching infrastructure.
The technical exploitation of this vulnerability occurs through a carefully crafted script element containing a language="php" attribute that is processed by the HttpCache class. When Symfony processes HTTP responses that contain such script elements, the framework fails to properly sanitize or validate the language attribute, allowing attackers to inject malicious PHP code that gets executed during the caching process. This represents a classic eval injection vulnerability, where user-controllable input is passed directly to an eval function or similar execution mechanism without proper sanitization. The vulnerability is classified as CWE-94, which specifically addresses "Improper Control of Generation of Code ('Code Injection')" and aligns with ATT&CK technique T1190 for "Exploit Public-Facing Application" and T1059.007 for "Command and Scripting Interpreter: Python."
The operational impact of this vulnerability is severe and far-reaching for any organization running affected Symfony applications. Attackers can leverage this flaw to execute arbitrary commands on the web server, potentially leading to complete system compromise, data exfiltration, and persistence mechanisms. The vulnerability affects multiple Symfony release lines including 2.3.x, 2.4.x, 2.5.x, and 2.6.x, indicating it was a widespread issue that impacted a significant portion of Symfony users. The attack vector requires only a single HTTP request containing malicious script tags, making it particularly dangerous as it can be exploited through various means including web application firewalls bypass techniques and automated scanning tools.
Organizations affected by CVE-2015-2308 should immediately implement the recommended mitigations including upgrading to the patched versions of Symfony 2.3.27, 2.5.11, and 2.6.6 across all affected application deployments. Additionally, network administrators should monitor for suspicious traffic patterns and implement proper input validation at multiple layers of the application architecture. The vulnerability demonstrates the critical importance of proper sanitization of user-controllable input and the potential for seemingly innocuous caching mechanisms to become attack vectors for full system compromise. Security teams should also consider implementing web application firewalls and runtime application self-protection mechanisms to detect and prevent exploitation attempts. This vulnerability serves as a stark reminder of the need for comprehensive security testing and the importance of keeping all framework components updated to protect against known attack patterns.