CVE-2023-39967 in WireMock
Summary
by MITRE • 09/07/2023
WireMock is a tool for mocking HTTP services. When certain request URLs like “@127.0.0.1:1234" are used in WireMock Studio configuration fields, the request might be forwarded to an arbitrary service reachable from WireMock’s instance. There are 3 identified potential attack vectors: via “TestRequester” functionality, webhooks and the proxy mode. As we can control HTTP Method, HTTP Headers, HTTP Data, it allows sending requests with the default level of credentials for the WireMock instance. The vendor has discontinued the affected Wiremock studio product and there will be no fix. Users are advised to find alternatives.
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Analysis
by VulDB Data Team • 09/07/2023
CVE-2023-39967 represents a critical server-side request forgery vulnerability in WireMock Studio, a popular HTTP mocking tool used extensively in development and testing environments. This vulnerability stems from insufficient input validation in the URL parsing mechanism, allowing attackers to craft malicious URLs that bypass normal network restrictions and potentially access internal services. The flaw specifically manifests when request URLs containing patterns like "@127.0.0.1:1234" are processed through the configuration fields, creating a path traversal scenario that enables arbitrary service forwarding. The vulnerability is categorized under CWE-918, Server-Side Request Forgery, which is classified as a critical threat in the OWASP Top Ten 2021, particularly concerning the exposure of internal systems to external attackers. The affected functionality operates through three primary attack vectors that leverage different WireMock Studio features including the TestRequester functionality, webhook processing capabilities, and proxy mode operations. These vectors create a multi-layered attack surface where an attacker can manipulate HTTP methods, headers, and data payloads to establish connections to internal services that would normally be restricted from external access. The attack leverages the default authentication credentials of the WireMock instance, which often include minimal security measures, allowing unauthorized access to potentially sensitive internal resources. This vulnerability directly maps to ATT&CK technique T1105, Remote File Execution, where adversaries establish connections to internal systems through compromised applications. The exploitation potential is particularly concerning in development environments where WireMock Studio instances may have elevated privileges or access to sensitive internal APIs and databases. The vulnerability's impact is amplified by the fact that WireMock Studio operates as a network service that may be exposed to untrusted networks, creating an attack surface that extends beyond typical development environments. Security researchers have identified that this issue can lead to information disclosure, lateral movement, and potential system compromise when internal services are accessible through the configured URLs. The vulnerability exists at the application layer where URL parsing fails to properly validate and sanitize input, allowing attackers to inject malicious hostnames or IP addresses. This behavior creates a dangerous precedent where legitimate configuration fields become attack vectors for unauthorized network access, undermining the security posture of applications that rely on WireMock for testing purposes. The discontinuation of the affected WireMock Studio product by the vendor eliminates any possibility of patching or remediation, forcing organizations to migrate to alternative solutions. Organizations using WireMock Studio in production or development environments should immediately implement network segmentation, firewall rules, and access controls to limit exposure to internal services. The vulnerability demonstrates the critical importance of input validation in network-facing applications and highlights the need for proper sandboxing of configuration mechanisms. Given the nature of this vulnerability and its potential for lateral movement within networks, organizations should consider implementing network monitoring solutions to detect suspicious outbound connections that may indicate exploitation attempts. The security implications extend beyond immediate access to internal services, as this vulnerability could enable attackers to map internal network topology and identify additional targets for further exploitation. Organizations should conduct thorough security assessments of their development environments to identify other potentially vulnerable applications and services that may be susceptible to similar attack patterns. The lack of vendor support for this vulnerability means that security teams must develop custom mitigation strategies, including implementing strict network policies and monitoring for unauthorized access patterns, while simultaneously planning migration to more secure alternatives that properly validate and sanitize all user inputs.