CVE-2012-3489 in PostgreSQL
Summary
by MITRE
The xml_parse function in the libxml2 support in the core server component in PostgreSQL 8.3 before 8.3.20, 8.4 before 8.4.13, 9.0 before 9.0.9, and 9.1 before 9.1.5 allows remote authenticated users to determine the existence of arbitrary files or URLs, and possibly obtain file or URL content that triggers a parsing error, via an XML value that refers to (1) a DTD or (2) an entity, related to an XML External Entity (aka XXE) issue.
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Analysis
by VulDB Data Team • 12/14/2021
The vulnerability described in CVE-2012-3489 represents a critical XML External Entity processing flaw within PostgreSQL's libxml2 integration, specifically affecting versions prior to the mentioned patches. This issue enables remote authenticated attackers to exploit the xml_parse function in the core server component, creating a significant information disclosure risk that extends beyond simple data exposure to potentially reveal sensitive file system contents or network resources. The vulnerability stems from insufficient validation of external entity references within XML processing, allowing malicious actors to construct XML documents that reference external resources through Document Type Definitions or XML entities.
The technical implementation of this vulnerability occurs through the manipulation of XML parsing behavior within PostgreSQL's database engine, where the xml_parse function fails to properly restrict access to external resources during XML document processing. When an XML value contains references to DTD elements or entity declarations that point to arbitrary file paths or URLs, the system attempts to resolve these references during parsing, potentially exposing file contents or network responses to the attacker. This behavior directly maps to CWE-611, which categorizes improper access control in XML parsers, and represents a classic XXE (XML External Entity) vulnerability pattern that has been widely documented in various software components.
The operational impact of this vulnerability extends beyond simple information disclosure, as authenticated users can leverage this weakness to map the file system structure of the database server or access network resources that should remain protected. Attackers can construct malicious XML payloads that reference local files, potentially exposing configuration files, database credentials, or other sensitive information stored on the server. The vulnerability also allows for potential denial of service conditions when malformed entity references cause parsing errors that may crash the database process or consume excessive resources. From an attacker's perspective, this vulnerability represents a significant escalation opportunity, as it provides insights into the underlying system architecture and can serve as a foundation for more sophisticated attacks.
Mitigation strategies for CVE-2012-3489 should focus on immediate patching of affected PostgreSQL versions to the recommended secure releases, which include PostgreSQL 8.3.20, 8.4.13, 9.0.9, and 9.1.5 respectively. Database administrators should also implement strict XML validation policies within their applications, disabling external entity resolution and DTD processing where possible. The use of parameterized queries and proper input sanitization can further reduce the attack surface, while network segmentation and access controls should limit the ability of unauthorized users to establish authenticated connections to the database. Organizations should also consider implementing database activity monitoring to detect anomalous XML processing patterns that might indicate exploitation attempts, aligning with ATT&CK technique T1078 for valid accounts and T1213 for data from information repositories. Additionally, regular security assessments and vulnerability scanning should be conducted to identify similar issues in other database components or applications that may be susceptible to similar XXE vulnerabilities.