CVE-2018-9116 in WireMock
Summary
by MITRE
An XXE vulnerability within WireMock before 2.16.0 allows a remote unauthenticated attacker to access local files and internal resources and potentially cause a Denial of Service.
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Analysis
by VulDB Data Team • 01/18/2020
The CVE-2018-9116 vulnerability represents a critical XML External Entity processing flaw in the WireMock mocking framework that affected versions prior to 2.16.0. This vulnerability resides in the way WireMock handles XML input during request processing, creating a pathway for remote attackers to exploit the system through malformed XML payloads. The vulnerability specifically impacts the HTTP server component of WireMock that processes incoming requests containing XML content, making it particularly dangerous in environments where WireMock is used as a service mock or proxy tool.
The technical flaw manifests when WireMock receives XML-formatted requests that contain external entity declarations or references to local resources. Attackers can craft malicious XML payloads that reference local files or internal network endpoints through the XXE processing mechanism. This vulnerability falls under the CWE-611 weakness category, which specifically addresses Improper Restriction of XML External Entity Reference, a well-documented vulnerability pattern that has been exploited in numerous security incidents across different frameworks and applications. The flaw allows attackers to perform unauthorized file access, potentially read sensitive system files, and gain information about the internal network structure through internal resource enumeration.
The operational impact of this vulnerability extends beyond simple information disclosure, as it can potentially lead to a complete system compromise. Remote unauthenticated attackers can leverage this vulnerability to access local files that may contain sensitive configuration data, database credentials, or application secrets. The ability to access internal resources means that attackers can perform reconnaissance activities to map internal network topologies, potentially identifying other vulnerable systems within the same network segment. Furthermore, the vulnerability can be exploited to cause denial of service conditions by triggering resource exhaustion through malicious entity references or by consuming excessive system resources during XML parsing operations.
Organizations using WireMock in production environments or development testing scenarios should prioritize immediate remediation by upgrading to version 2.16.0 or later, which includes proper XML entity validation and restrictions. Security teams should implement network segmentation and access controls to limit exposure of WireMock instances to untrusted networks. Additionally, organizations should consider implementing XML input validation at the application level and monitoring for suspicious XML processing activities. The vulnerability aligns with several ATT&CK techniques including T1059.007 for XML External Entity Processing and T1082 for system information discovery, making it a significant concern for organizations following the MITRE ATT&CK framework for threat modeling and defense planning.