CVE-2019-0193 in Solr
Summary
by MITRE
In Apache Solr, the DataImportHandler, an optional but popular module to pull in data from databases and other sources, has a feature in which the whole DIH configuration can come from a request's "dataConfig" parameter. The debug mode of the DIH admin screen uses this to allow convenient debugging / development of a DIH config. Since a DIH config can contain scripts, this parameter is a security risk. Starting with version 8.2.0 of Solr, use of this parameter requires setting the Java System property "enable.dih.dataConfigParam" to true.
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Analysis
by VulDB Data Team • 09/09/2024
The vulnerability described in CVE-2019-0193 affects Apache Solr's DataImportHandler component, which serves as a critical data integration module enabling users to import data from various sources including databases, files, and web services. This component operates through configuration files that define how data should be extracted, transformed, and loaded into the search platform. The DataImportHandler has long been a popular feature due to its flexibility in handling complex data integration tasks, making it an essential tool for many organizations relying on Solr for their search and indexing needs.
The core technical flaw lies within the debug functionality of the DataImportHandler admin interface, which allows users to pass configuration parameters directly through HTTP requests via the "dataConfig" parameter. This feature was designed for developer convenience during the debugging and development phases of DIH configurations, eliminating the need to modify configuration files directly. However, this convenience introduces a significant security risk as the dataConfig parameter can contain executable scripts, making it susceptible to code injection attacks. The vulnerability exists because the system accepts and processes these parameters without proper validation or sanitization, effectively allowing remote code execution through carefully crafted requests that can leverage the scripting capabilities embedded within the DIH configuration.
The operational impact of this vulnerability is severe and aligns with CWE-94, which describes "Improper Control of Generation of Code ('Code Injection')" as the underlying weakness. An attacker who can submit requests to the Solr server could potentially execute arbitrary code with the privileges of the Solr process, leading to complete system compromise. This vulnerability affects all versions of Apache Solr prior to 8.2.0, making it particularly dangerous as many organizations may have legacy installations that remain unpatched. The attack vector requires only basic HTTP request capabilities, making exploitation relatively straightforward for threat actors with minimal technical expertise. The vulnerability particularly impacts organizations that have not properly configured their Solr instances with restricted access controls, as the attack can be executed remotely without authentication.
The remediation strategy implemented by Apache Solr in version 8.2.0 addresses this vulnerability through a mandatory system property configuration approach. The solution requires administrators to explicitly set the Java System property "enable.dih.dataConfigParam" to true before the dataConfig parameter functionality becomes available. This mitigation approach follows security best practices by implementing a default-deny model where the feature is disabled by default and must be explicitly enabled by system administrators who understand the security implications. Organizations should also implement additional controls such as network segmentation, firewall rules restricting access to Solr endpoints, and proper authentication mechanisms to prevent unauthorized access to the DataImportHandler functionality. This vulnerability demonstrates the importance of the principle of least privilege and proper input validation in security design, as outlined in the ATT&CK framework under techniques related to code injection and privilege escalation.