CVE-2023-2161 in OPC Factory Server
Summary
by MITRE • 05/16/2023
A CWE-611: Improper Restriction of XML External Entity Reference vulnerability exists that could cause unauthorized read access to the file system when a malicious configuration file is loaded on to the software by a local user.
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Analysis
by VulDB Data Team • 06/09/2023
This vulnerability represents a critical security flaw classified as CWE-611, which specifically addresses improper restriction of XML external entity references. The issue manifests when software applications fail to adequately validate or sanitize XML input, allowing attackers to exploit XML parsing mechanisms to access sensitive local resources. The vulnerability is particularly concerning because it requires only local user privileges to exploit, making it accessible through social engineering or privilege escalation techniques within a compromised system. When a maliciously crafted XML configuration file is loaded into the vulnerable application, the XML parser processes external entity references that can be manipulated to read arbitrary files from the local file system.
The technical exploitation occurs through XML external entity processing where attackers can construct XML documents containing references to local files or network resources. This vulnerability falls under the category of server-side request forgery and information disclosure attacks, as it allows unauthorized file access that could include system configuration files, user credentials, or sensitive application data. The flaw essentially enables attackers to bypass normal file access controls and retrieve files that should otherwise be protected from unauthorized access. This type of vulnerability is commonly found in applications that process user-supplied XML data without proper input validation or secure XML parser configurations.
The operational impact of this vulnerability extends beyond simple information disclosure, as it can lead to complete system compromise when combined with other attack vectors. Local users who can influence XML configuration files can potentially access sensitive data, escalate privileges, or gather intelligence about the system's internal structure. This vulnerability is particularly dangerous in enterprise environments where configuration files may contain database connection strings, API keys, or other sensitive credentials. The attack surface is broad since many applications parse XML configuration files during startup or runtime, and the vulnerability can be exploited through various legitimate application functions that accept XML input.
Security mitigations for this vulnerability should focus on implementing strict XML parser configurations that disable external entity processing and DTD resolution. Organizations should enforce secure coding practices that include input validation, XML schema validation, and proper error handling to prevent exploitation. The implementation of secure XML parsers with restricted entity expansion limits and the use of XML processing libraries that disable external entity resolution by default are essential defensive measures. Additionally, regular security assessments should include testing for XML external entity vulnerabilities, and system administrators should monitor for unusual file access patterns that might indicate exploitation attempts. This vulnerability aligns with ATT&CK techniques related to privilege escalation and credential access, making it a significant concern for organizations following standard security frameworks and compliance requirements.