CVE-2023-50571 in easy-rules-mvel
Summary
by MITRE • 12/29/2023
easy-rules-mvel v4.1.0 was discovered to contain a remote code execution (RCE) vulnerability via the component MVELRule.
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Analysis
by VulDB Data Team • 01/21/2024
The vulnerability identified as CVE-2023-50571 affects the easy-rules-mvel library version 4.1.0 and represents a critical remote code execution flaw that can be exploited by attackers to execute arbitrary code on affected systems. This vulnerability specifically resides within the MVELRule component of the library, which is designed to facilitate rule-based processing using the MVEL expression language. The issue stems from inadequate input validation and sanitization mechanisms that fail to properly handle untrusted data passed to the MVEL expression evaluator, creating an avenue for malicious actors to inject and execute arbitrary code remotely without requiring authentication or privileged access.
The technical implementation of this vulnerability leverages the MVEL (MVFLEX Expression Language) engine's capability to evaluate dynamic expressions, which when combined with insufficient security controls creates a dangerous attack surface. When the MVELRule component processes user-provided data without proper sanitization, it can interpret malicious expressions as executable code rather than mere data. This flaw aligns with CWE-94, which describes improper control of generation of code, specifically indicating weaknesses in the handling of dynamic code generation where user-supplied inputs are not properly validated or sanitized. The vulnerability essentially allows attackers to craft expressions that bypass normal execution boundaries and execute system commands or arbitrary code within the context of the application running the vulnerable library.
From an operational perspective, this vulnerability poses significant risks to organizations that utilize the easy-rules-mvel library in their applications, particularly those that process untrusted input through rule evaluation mechanisms. The impact extends beyond simple code execution to potentially enable full system compromise, data exfiltration, and lateral movement within network environments. Attackers can exploit this vulnerability to establish persistent access, deploy additional malware, or use the compromised system as a launch point for further attacks against internal infrastructure. The vulnerability is particularly concerning because it can be exploited remotely without requiring any prior authentication, making it an attractive target for automated exploitation campaigns. This characteristic places organizations at risk regardless of their network security posture, as the vulnerability can be triggered through any interface that processes user input through the vulnerable rule evaluation component.
The mitigation strategies for this vulnerability should prioritize immediate remediation through version updates, as the issue has been addressed in subsequent releases of the easy-rules-mvel library. Organizations should conduct comprehensive inventory assessments to identify all systems and applications utilizing the vulnerable library, implementing network segmentation and monitoring to detect potential exploitation attempts. Input validation and sanitization measures should be strengthened at all application layers that interact with rule evaluation components, while principle of least privilege configurations should be enforced to limit the potential impact of successful exploitation. Security teams should also implement runtime application self-protection mechanisms and consider deploying web application firewalls to monitor and block suspicious expression evaluation patterns. Additionally, organizations should review their software supply chain processes to ensure that vulnerable dependencies are identified and remediated proactively, aligning with industry best practices for vulnerability management and incident response as outlined in frameworks such as the MITRE ATT&CK matrix for defensive strategies against remote code execution threats.