CVE-2016-3090 in Struts
Summary
by MITRE
The TextParseUtil.translateVariables method in Apache Struts 2.x before 2.3.20 allows remote attackers to execute arbitrary code via a crafted OGNL expression with ANTLR tooling.
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Analysis
by VulDB Data Team • 01/21/2021
The vulnerability identified as CVE-2016-3090 represents a critical remote code execution flaw within the Apache Struts 2 framework that affects versions prior to 2.3.20. This vulnerability resides in the TextParseUtil.translateVariables method which processes variable substitutions within the framework's configuration and user input handling mechanisms. The flaw specifically leverages the ANTLR tooling component that Apache Struts uses for parsing and processing OGNL (Object-Graph Navigation Language) expressions, creating a pathway for malicious actors to inject and execute arbitrary code on vulnerable systems.
The technical exploitation of this vulnerability occurs through the manipulation of OGNL expressions that are processed by the vulnerable translateVariables method. When user-supplied input containing specially crafted OGNL expressions is processed through the framework's variable translation mechanism, the ANTLR parser incorrectly interprets these expressions and executes them as code rather than treating them as simple string replacements. This represents a classic command injection vulnerability where the framework's legitimate parsing functionality becomes a vector for arbitrary code execution. The vulnerability is categorized under CWE-94 as "Improper Control of Generation of Code ('Code Injection')" and specifically manifests as an OGNL injection attack that bypasses normal input validation mechanisms.
The operational impact of this vulnerability is severe and far-reaching within enterprise environments that utilize Apache Struts 2 frameworks. Attackers can leverage this flaw to execute arbitrary commands on affected servers with the privileges of the web application process, potentially leading to complete system compromise. The vulnerability affects web applications that process user input through Struts' parameter handling mechanisms, making it particularly dangerous in applications with web forms, REST APIs, or any interface that accepts external input. Organizations running vulnerable versions of Apache Struts 2 are at significant risk of data breaches, system infiltration, and unauthorized access to sensitive information stored within or accessible through the compromised applications.
The attack surface for this vulnerability extends beyond simple web application exploitation to include potential lateral movement within networks where compromised systems may serve as launch points for further attacks. According to ATT&CK framework categorization, this vulnerability maps to T1059.001 "Command and Scripting Interpreter: PowerShell" and T1059.007 "Command and Scripting Interpreter: Python" as attackers can leverage the executed code to perform various malicious activities including privilege escalation, data exfiltration, and persistence establishment. Organizations should immediately implement mitigation strategies including applying the patched versions of Apache Struts 2, implementing web application firewalls, and conducting comprehensive vulnerability assessments to identify any potential exploitation attempts. The vulnerability demonstrates the critical importance of keeping enterprise frameworks updated and implementing robust input validation mechanisms to prevent injection-based attacks that can compromise entire application stacks.
The remediation approach for CVE-2016-3090 requires immediate deployment of Apache Struts 2 version 2.3.20 or later, which includes patches addressing the OGNL expression handling within the TextParseUtil.translateVariables method. Security teams should also implement input validation controls, sanitize all user-supplied data, and consider implementing additional security layers such as web application firewalls to detect and block malicious OGNL expressions. Organizations should conduct thorough security assessments of their web applications to identify all potential entry points and ensure comprehensive protection against similar injection vulnerabilities that could leverage the same underlying parsing mechanisms.