CVE-2023-37200 in EcoStruxure OPC UA Server Expert
Summary
by MITRE • 07/12/2023
A CWE-611: Improper Restriction of XML External Entity Reference vulnerability exists that could cause loss of confidentiality when replacing a project file on the local filesystem and after manual restart of the server.
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Analysis
by VulDB Data Team • 07/30/2023
The vulnerability identified as CVE-2023-37200 represents a critical security flaw classified under CWE-611, which specifically addresses improper restriction of XML external entity references. This weakness manifests in systems where XML processing is performed without adequate safeguards against external entity resolution, creating a pathway for malicious actors to exploit the application's handling of XML data. The vulnerability becomes particularly dangerous when users perform actions such as replacing project files on the local filesystem, as this creates an attack surface where crafted XML content can be introduced into the system. The security implications extend beyond simple data exposure, as the flaw allows for potential information disclosure that could compromise system confidentiality.
The technical mechanism behind this vulnerability involves XML parsers that fail to properly validate or restrict external entity references during document processing. When a user replaces a project file containing XML content, the application processes this data without sufficient input sanitization, enabling attackers to craft malicious XML documents that reference external resources. These external references can be configured to point to internal system resources, network locations, or even malicious servers that can be used to exfiltrate sensitive data or perform other malicious activities. The vulnerability's exploitation requires a specific sequence of user actions including file replacement followed by a manual server restart, which suggests the flaw may be triggered during application initialization or configuration loading phases where XML documents are parsed and processed.
The operational impact of CVE-2023-37200 extends significantly beyond immediate data loss scenarios, as the vulnerability can facilitate broader system compromise when combined with other attack vectors. The requirement for a manual server restart indicates that the vulnerability may be exploitable during application startup or configuration reload processes, potentially allowing attackers to inject malicious payloads that persist across system restarts. This characteristic aligns with ATT&CK technique T1059.007 for XML External Entity Processing, which emphasizes how such vulnerabilities can be leveraged for data exfiltration and system reconnaissance. The confidentiality breach could expose sensitive project data, system configurations, or user information stored within the application's XML processing components, making this vulnerability particularly concerning for organizations handling proprietary or regulated data.
Mitigation strategies for CVE-2023-37200 should focus on implementing robust XML parser configurations that disable external entity resolution and DTD processing. Organizations must ensure that all XML processing components are configured to reject external entity references and that proper input validation is enforced before any XML content is processed. Security measures should include implementing strict XML schema validation, using secure XML parsers that default to safe processing modes, and establishing automated monitoring for suspicious file replacement activities. The implementation of principle of least privilege access controls and network segmentation can help limit the potential impact of successful exploitation attempts. Additionally, regular security assessments and penetration testing should be conducted to identify similar vulnerabilities in XML processing components, while maintaining updated security patches and monitoring for related threats in the cybersecurity landscape. The vulnerability's classification under CWE-611 emphasizes the need for comprehensive XML security controls that align with industry best practices for preventing XML external entity attacks and protecting against information disclosure threats.