CVE-2016-3153 in SPIP
Summary
by MITRE
SPIP 2.x before 2.1.19, 3.0.x before 3.0.22, and 3.1.x before 3.1.1 allows remote attackers to execute arbitrary PHP code by adding content, related to the filtrer_entites function.
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Analysis
by VulDB Data Team • 02/05/2019
The vulnerability identified as CVE-2016-3153 affects the SPIP content management system, specifically targeting versions prior to 2.1.19 in the 2.x branch, 3.0.22 in the 3.0.x branch, and 3.1.1 in the 3.1.x branch. This represents a critical remote code execution flaw that stems from improper input validation within the filtrer_entites function, which serves as a core filtering mechanism for processing user-submitted content. The vulnerability exists in the fundamental data sanitization process that SPIP employs to handle text input from various sources including form submissions, comments, and content management interfaces.
The technical flaw manifests through a dangerous interaction between the filtrer_entites function and PHP's variable handling mechanisms. When user-provided content passes through this function, the system fails to properly sanitize special characters and escape sequences that could be interpreted as PHP code. Attackers can exploit this weakness by crafting malicious input containing PHP code snippets that bypass the intended filtering process. The vulnerability operates at the application layer and specifically targets the server-side processing of content, allowing unauthorized execution of arbitrary PHP commands with the privileges of the web application. This flaw directly maps to CWE-94, which describes "Improper Control of Generation of Code ('Code Injection')" and falls under the broader category of code injection vulnerabilities that enable remote attackers to execute malicious code on the target system.
The operational impact of CVE-2016-3153 extends far beyond simple data corruption or content manipulation. Successful exploitation provides attackers with complete control over the affected SPIP installation, enabling them to access sensitive data, modify content, create new user accounts, and potentially escalate privileges to gain access to underlying server resources. This vulnerability can be leveraged for persistent backdoor establishment, data exfiltration, and further network reconnaissance. The attack surface is particularly concerning because SPIP is widely used for government and organizational websites, making these systems prime targets for nation-state actors and sophisticated threat groups. The vulnerability aligns with ATT&CK technique T1059.007, which covers "Command and Scripting Interpreter: PowerShell," and T1566, covering "Phishing," as attackers can use this vulnerability to establish persistent access and execute commands remotely.
Mitigation strategies for CVE-2016-3153 require immediate patching of all affected SPIP installations to the recommended versions that contain fixed implementations of the filtrer_entites function. Organizations should also implement network-level protections including firewall rules that restrict access to administrative interfaces and content management functions. Input validation should be enhanced at multiple layers including application-level filtering, database query sanitization, and web application firewall rules. Security monitoring should focus on unusual content submission patterns and unexpected PHP execution activities. Additionally, implementing principle of least privilege for web application accounts and regular security audits of content management systems will help reduce the overall risk exposure. The vulnerability highlights the critical importance of proper input sanitization and the potential consequences of inadequate code review processes in content management systems.