CVE-2012-3488 in PostgreSQL
Summary
by MITRE
The libxslt support in contrib/xml2 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 does not properly restrict access to files and URLs, which allows remote authenticated users to modify data, obtain sensitive information, or trigger outbound traffic to arbitrary external hosts by leveraging (1) stylesheet commands that are permitted by the libxslt security options or (2) an xslt_process feature, related to an XML External Entity (aka XXE) issue.
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Analysis
by VulDB Data Team • 12/14/2021
The vulnerability identified as CVE-2012-3488 represents a critical security flaw in PostgreSQL's libxslt support mechanism within the contrib/xml2 module. This issue affects multiple PostgreSQL versions including 8.3.x before 8.3.20, 8.4.x before 8.4.13, 9.0.x before 9.0.9, and 9.1.x before 9.1.5. The core problem lies in the improper restriction of file and URL access within the XML processing capabilities, creating a pathway for remote authenticated attackers to exploit the system through malicious stylesheet commands or the xslt_process feature. This vulnerability directly relates to XML External Entity processing mechanisms that can be leveraged for unauthorized data manipulation and information disclosure.
The technical implementation of this vulnerability stems from insufficient validation of XML stylesheet commands and URL access within PostgreSQL's XML processing pipeline. When PostgreSQL processes XML data through its contrib/xml2 module, it utilizes libxslt for stylesheet transformations. The flaw occurs because the security restrictions imposed by libxslt are not properly enforced, allowing authenticated users to craft malicious XML content that can access local files or initiate outbound connections to arbitrary external hosts. This represents a classic XML External Entity processing vulnerability where the system fails to properly sanitize external references in XML documents, enabling attackers to manipulate the processing behavior through carefully constructed input.
From an operational perspective, this vulnerability creates significant risk for PostgreSQL database systems as it allows authenticated attackers to perform data modification, information disclosure, and potentially initiate outbound network connections. The impact extends beyond simple data theft since attackers can leverage the xslt_process feature to trigger network traffic to external hosts, potentially enabling command and control communications or data exfiltration. The vulnerability affects systems where XML processing is enabled and authenticated users have access to database functions that utilize the contrib/xml2 module, making it particularly dangerous in environments with multiple database users or applications that process untrusted XML input.
The security implications of CVE-2012-3488 align with CWE-611 (Improper Restriction of XML External Entity Reference) and can be mapped to ATT&CK technique T1071.004 (Application Layer Protocol: DNS) through the potential for outbound network traffic generation. Organizations using affected PostgreSQL versions face risks of unauthorized data manipulation, information leakage through file access, and possible network reconnaissance activities. The vulnerability is particularly concerning because it requires only authenticated access, meaning that users with legitimate database permissions can exploit this flaw to gain additional privileges or access sensitive information.
Mitigation strategies for this vulnerability include upgrading to the patched versions of PostgreSQL where the libxslt security restrictions have been properly implemented. Database administrators should ensure that all affected versions are updated promptly and that proper access controls are maintained to limit the number of authenticated users with XML processing capabilities. Additionally, implementing network monitoring to detect unusual outbound traffic patterns can help identify exploitation attempts. Organizations should also consider disabling unnecessary XML processing features when not required, and implementing proper input validation for all XML data processed by the database to prevent exploitation through malformed XML content. The fix addresses the underlying XXE processing issues by implementing stricter validation of external entity references and URL access within the libxslt processing pipeline, preventing unauthorized file access and outbound network connections.