CVE-2022-23463 in Discovery
Summary
by MITRE • 09/24/2022
Nepxion Discovery is a solution for Spring Cloud. Discover is vulnerable to SpEL Injection in discovery-commons. DiscoveryExpressionResolver’s eval method is evaluating expression with a StandardEvaluationContext, allowing the expression to reach and interact with Java classes such as java.lang.Runtime, leading to Remote Code Execution. There is no patch available for this issue at time of publication. There are no known workarounds.
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 10/23/2022
The vulnerability CVE-2022-23463 affects Nepxion Discovery, a comprehensive solution for Spring Cloud environments that provides service discovery and routing capabilities. This system serves as a critical component in microservices architectures, enabling dynamic service registration and discovery mechanisms. The vulnerability resides within the discovery-commons module, specifically within the DiscoveryExpressionResolver class which handles expression evaluation for various discovery operations. The affected system processes user-supplied expressions that are evaluated at runtime, creating a dangerous attack surface that can be exploited by malicious actors to compromise the entire service discovery infrastructure.
The technical flaw manifests through Server-Side Expression Language (SpEL) injection in the eval method of DiscoveryExpressionResolver. When the system processes expressions, it utilizes StandardEvaluationContext which provides full access to the Java runtime environment. This evaluation context allows attackers to craft malicious expressions that can directly interact with core Java classes including java.lang.Runtime, java.lang.ProcessBuilder, and other system-level components. The vulnerability essentially enables an attacker to inject arbitrary expressions that bypass normal security boundaries and execute arbitrary code within the context of the running application. This represents a critical security flaw that transforms what should be a safe expression evaluation mechanism into a potential gateway for complete system compromise.
The operational impact of this vulnerability is severe and far-reaching for organizations using Nepxion Discovery in their Spring Cloud deployments. Remote Code Execution (RCE) allows attackers to gain complete control over affected systems, enabling them to execute arbitrary commands, access sensitive data, modify service configurations, and potentially pivot to other systems within the network. The vulnerability affects the core service discovery functionality, which means that an attacker could compromise not just individual services but the entire microservices ecosystem. Organizations relying on this discovery mechanism for load balancing, routing, and service registration would face catastrophic consequences, as attackers could manipulate service endpoints, redirect traffic, or completely disable critical infrastructure. The lack of available patches and workarounds compounds the risk, leaving affected systems vulnerable until remediation is implemented.
Mitigation strategies for this vulnerability must be implemented immediately given the absence of official patches. Organizations should consider restricting network access to the affected discovery services, implementing strict input validation and sanitization for all expression inputs, and deploying network segmentation to limit the attack surface. The principle of least privilege should be enforced by configuring the evaluation context to limit access to dangerous Java classes and methods. Security teams should also implement monitoring and logging mechanisms to detect suspicious expression evaluation patterns that might indicate exploitation attempts. According to CWE standards, this vulnerability maps to CWE-94 which covers "Improper Control of Generation of Code ('Code Injection')" and aligns with ATT&CK techniques such as T1059.001 for Command and Scripting Interpreter and T1071.004 for Application Layer Protocol. Organizations should also consider implementing Web Application Firewalls and runtime application self-protection mechanisms to detect and block malicious expression injection attempts. The most effective long-term solution involves upgrading to patched versions of Nepxion Discovery or implementing comprehensive expression validation frameworks that prevent dangerous class access while maintaining legitimate functionality.