CVE-2018-1308 in Solr
Summary
by MITRE
This vulnerability in Apache Solr 1.2 to 6.6.2 and 7.0.0 to 7.2.1 relates to an XML external entity expansion (XXE) in the `&dataConfig=<inlinexml>` parameter of Solr's DataImportHandler. It can be used as XXE using file/ftp/http protocols in order to read arbitrary local files from the Solr server or the internal network.
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Analysis
by VulDB Data Team • 02/27/2023
The vulnerability described in CVE-2018-1308 represents a critical XML external entity expansion flaw within Apache Solr's DataImportHandler component. This vulnerability affects versions ranging from 1.2 through 6.6.2 and specifically 7.0.0 to 7.2.1, creating a significant security risk for organizations relying on these software versions. The flaw manifests when the dataConfig parameter accepts inline xml content that can be exploited through the XML parsing mechanism, allowing attackers to manipulate the parsing process and execute malicious operations. The vulnerability stems from insufficient input validation and sanitization within the DataImportHandler's XML processing pipeline, which fails to properly restrict external entity references during XML document parsing.
The technical exploitation of this vulnerability occurs through the manipulation of the dataConfig parameter within the DataImportHandler's configuration. Attackers can construct malicious XML payloads that include external entity declarations, enabling them to leverage file, ftp, and http protocols to access arbitrary local files on the Solr server or internal network resources. This occurs because the XML parser processes external entity references without proper restrictions, allowing attackers to traverse the file system and potentially access sensitive configuration files, database credentials, or other confidential information stored on the server. The vulnerability specifically targets the XML parsing functionality used by Solr's DataImportHandler, which is designed to import data from various sources including databases, files, and web services, making it a prime target for attackers seeking to extract sensitive data from the system.
The operational impact of CVE-2018-1308 extends beyond simple information disclosure, as it can enable attackers to perform reconnaissance activities and potentially escalate privileges within the affected system. Organizations running vulnerable versions of Apache Solr face the risk of unauthorized data access, including sensitive business information, user credentials, and system configurations that could be stored in files accessible through the file protocol. The vulnerability's ability to access internal network resources through ftp and http protocols means that attackers could potentially map network topology, access internal databases, or leverage the compromised system as a pivot point for further attacks. This aligns with ATT&CK technique T1083 (File and Directory Discovery) and T1046 (Network Service Scanning) as attackers can use the vulnerability to enumerate system resources and network configurations. The vulnerability also represents a direct violation of CWE-611 (Improper Restriction of XML External Entity Reference) which specifically addresses the security risks associated with XML external entity processing.
Mitigation strategies for CVE-2018-1308 primarily focus on upgrading to patched versions of Apache Solr where the XML parsing has been properly restricted to prevent external entity expansion. Organizations should implement immediate patches for versions 6.6.2 and 7.2.1, as well as ensure that all systems running vulnerable versions are updated to the latest stable releases. Additionally, administrators should configure the DataImportHandler to disable external entity processing entirely by setting appropriate XML parser configurations that prevent the expansion of external entities. Network-level mitigations include implementing firewall rules to restrict access to Solr endpoints and limiting the attack surface by disabling unnecessary features. Security monitoring should be enhanced to detect suspicious XML parsing activities and anomalous file access patterns that may indicate exploitation attempts. Organizations should also conduct thorough vulnerability assessments to identify any other systems running vulnerable versions of Solr and ensure that proper input validation is implemented for all XML processing components throughout their infrastructure. The vulnerability serves as a reminder of the critical importance of proper XML parsing security and the need for continuous security updates and patch management processes within enterprise environments.