CVE-2018-7783 in SoMachine Basic
Summary
by MITRE
Schneider Electric SoMachine Basic prior to v1.6 SP1 suffers from an XML External Entity (XXE) vulnerability using the DTD parameter entities technique resulting in disclosure and retrieval of arbitrary data on the affected node via out-of-band (OOB) attack. The vulnerability is triggered when input passed to the xml parser is not sanitized while parsing the xml project/template file.
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Analysis
by VulDB Data Team • 02/25/2020
The vulnerability identified as CVE-2018-7783 affects Schneider Electric SoMachine Basic software versions prior to v1.6 SP1, representing a critical XML External Entity vulnerability that leverages DTD parameter entities for data exfiltration. This flaw exists within the software's XML parser implementation, specifically when processing project or template files that contain unvalidated user input. The vulnerability operates through an out-of-band attack vector, enabling attackers to retrieve arbitrary data from the affected system by exploiting the improper sanitization of input passed to the XML parser. The security implications are particularly severe for industrial control systems where SoMachine Basic is deployed, as it provides attackers with the capability to extract sensitive information from the target environment without requiring direct network access to the system.
The technical exploitation of this vulnerability relies on the XML parser's handling of DTD parameter entities, which allows attackers to construct malicious XML documents that reference external resources through parameter entities. When the vulnerable parser processes these documents, it attempts to resolve the external references, enabling the attacker to establish communication channels that can be used to exfiltrate data from the system. This particular variant of XXE vulnerability is classified under CWE-611 as an Improper Restriction of XML External Entity Reference, where the system fails to properly validate or sanitize external entity references in XML documents. The attack mechanism typically involves crafting XML content that includes parameter entity declarations referencing external resources, which when processed by the vulnerable parser, triggers the out-of-band data retrieval process.
The operational impact of this vulnerability extends beyond simple data disclosure, as it represents a significant threat to industrial control system security and operational integrity. Attackers can leverage this vulnerability to access sensitive configuration data, system information, and potentially other confidential resources stored on the affected node. The out-of-band nature of the attack means that data exfiltration occurs through covert channels that are difficult to detect through traditional network monitoring approaches. This vulnerability directly impacts the confidentiality and integrity aspects of the CIA triad, as unauthorized parties can gain access to system information that should remain protected. Organizations using SoMachine Basic in industrial environments face particular risk, as this vulnerability could enable attackers to gather intelligence about system configurations, network topology, and operational parameters that could facilitate further attacks.
Mitigation strategies for CVE-2018-7783 require immediate implementation of software updates to version v1.6 SP1 or later, which includes patches addressing the XML parser sanitization issues. Organizations should also implement XML parser configuration changes that disable external entity resolution and DTD processing, effectively preventing the exploitation of XXE vulnerabilities. Network segmentation and access controls should be strengthened to limit potential attack vectors, while security monitoring systems should be enhanced to detect unusual outbound network connections that may indicate OOB XXE attacks. The vulnerability's classification under ATT&CK technique T1213.002 for Data from Information Repositories highlights the need for comprehensive monitoring of data access patterns and system information gathering activities. Additionally, input validation mechanisms should be strengthened to ensure that all XML content is properly sanitized before processing, and regular security assessments should be conducted to identify potential vulnerabilities in industrial control system software components.