CVE-2013-6407 in Solr
Summary
by MITRE
The UpdateRequestHandler for XML in Apache Solr before 4.1 allows remote attackers to have an unspecified impact via XML data containing an external entity declaration in conjunction with an entity reference, related to an XML External Entity (XXE) issue.
Be aware that VulDB is the high quality source for vulnerability data.
Analysis
by VulDB Data Team • 01/11/2022
The vulnerability identified as CVE-2013-6407 represents a critical XML External Entity (XXE) flaw in Apache Solr versions prior to 4.1. This vulnerability resides within the UpdateRequestHandler component that processes XML data submissions to the search platform. The issue manifests when Solr receives XML content containing external entity declarations combined with entity references, creating a pathway for malicious actors to exploit the system's XML parsing capabilities.
The technical flaw stems from insufficient input validation and sanitization within Solr's XML processing pipeline. When the UpdateRequestHandler encounters XML data with external entity declarations, it fails to properly restrict access to external resources, allowing attackers to reference external entities that could contain malicious content or sensitive system information. This vulnerability specifically affects the XML parsing mechanisms that handle document updates and indexing operations within the Solr search platform.
The operational impact of this XXE vulnerability is significant and multifaceted. Remote attackers can leverage this flaw to perform various malicious activities including server-side request forgery attacks, internal network reconnaissance, and potential data exfiltration. The vulnerability enables attackers to access local files, perform port scanning of internal systems, and potentially execute arbitrary code depending on the underlying system configuration and permissions. This represents a severe threat to organizations relying on Solr for document management and search functionality.
From a cybersecurity perspective, this vulnerability aligns with CWE-611 (Improper Restriction of XML External Entity Reference) and maps to ATT&CK technique T1071.004 (Application Layer Protocol: DNS) when used for network reconnaissance. The vulnerability demonstrates the importance of implementing proper XML parsing security measures and highlights the risks associated with enabling external entity processing in enterprise search platforms. Organizations should prioritize immediate remediation by upgrading to Apache Solr 4.1 or later versions that include proper XXE protection mechanisms.
Mitigation strategies should include implementing strict XML parsing configurations that disable external entity resolution, deploying web application firewalls with XXE detection capabilities, and conducting regular security assessments of XML processing components. Additionally, network segmentation and access controls should be implemented to limit potential attack surface exposure. The vulnerability underscores the necessity of maintaining up-to-date software versions and implementing comprehensive security monitoring for XML-based services to prevent exploitation of similar XXE vulnerabilities in other components.