CVE-2017-14868 in Restlet
Summary
by MITRE
Restlet Framework before 2.3.11, when using SimpleXMLProvider, allows remote attackers to access arbitrary files via an XXE attack in a REST API HTTP request. This affects use of the Jax-rs extension.
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Analysis
by VulDB Data Team • 01/16/2023
The CVE-2017-14868 vulnerability represents a critical server-side request forgery issue within the Restlet Framework version 2.3.10 and earlier. This vulnerability specifically impacts applications that utilize the SimpleXMLProvider component alongside Jax-rs extensions, creating an attack surface where malicious actors can exploit XML External Entity processing flaws. The vulnerability stems from insufficient input validation and proper XML parsing mechanisms within the framework's handling of REST API requests, allowing attackers to craft specially malformed XML payloads that trigger unintended file system access patterns.
The technical flaw manifests when the SimpleXMLProvider processes incoming XML data without adequate protection against external entity references. Attackers can construct XML documents containing malicious entity declarations that reference local files on the server system through protocols like file:// or http://. When the vulnerable Restlet Framework processes these requests, it fails to properly sanitize the XML input, enabling the XML parser to resolve external entities and potentially read sensitive files from the server's file system. This XXE attack vector allows adversaries to access arbitrary files that should normally be restricted from external access, potentially exposing configuration files, database credentials, or other sensitive data stored on the server.
The operational impact of this vulnerability extends beyond simple information disclosure, as it can enable attackers to perform reconnaissance activities and potentially escalate privileges within the affected system. The vulnerability affects REST API endpoints that accept XML input and process it through the SimpleXMLProvider, making it particularly dangerous for web services that handle sensitive data processing. Security researchers have classified this issue under CWE-611, which specifically addresses Improper Restriction of XML External Entity Reference, and it aligns with ATT&CK technique T1213.002 for Data from Information Repositories. Organizations using Restlet Framework versions prior to 2.3.11 face significant risk of unauthorized file access, which could lead to complete system compromise if sensitive configuration files or database connection strings are exposed.
Mitigation strategies for CVE-2017-14868 require immediate patching of the Restlet Framework to version 2.3.11 or later, which includes proper XML entity validation and restriction mechanisms. Organizations should also implement XML input validation at multiple layers, including configuring the XML parser to disable external entity resolution entirely and implementing proper access controls for file system resources. Network segmentation and API gateway implementations can provide additional defense-in-depth measures by restricting direct file system access and monitoring for suspicious XML parsing patterns. Security teams should conduct comprehensive vulnerability assessments to identify all applications utilizing affected Restlet Framework versions and ensure proper input sanitization for all XML processing components within their REST API implementations. Additionally, implementing automated security scanning tools that can detect XXE vulnerabilities in API endpoints will help prevent similar issues from being introduced in future development cycles.