CVE-2012-0866 in PostgreSQL
Summary
by MITRE
CREATE TRIGGER in PostgreSQL 8.3.x before 8.3.18, 8.4.x before 8.4.11, 9.0.x before 9.0.7, and 9.1.x before 9.1.3 does not properly check the execute permission for trigger functions marked SECURITY DEFINER, which allows remote authenticated users to execute otherwise restricted triggers on arbitrary data by installing the trigger on an attacker-owned table.
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Analysis
by VulDB Data Team • 03/21/2021
The vulnerability identified as CVE-2012-0866 represents a critical authorization flaw in PostgreSQL database management systems affecting versions prior to specific patch releases. This issue stems from inadequate permission checking mechanisms within the trigger execution framework, particularly when dealing with functions marked with SECURITY DEFINER attribute. The flaw allows authenticated attackers to bypass normal access controls and execute restricted trigger functions against arbitrary database objects, creating a significant escalation of privileges vulnerability.
The technical root cause of this vulnerability lies in the improper validation of execute permissions for trigger functions that are designated as SECURITY DEFINER. In PostgreSQL, SECURITY DEFINER functions execute with the privileges of the function owner rather than the caller, which is a legitimate security feature designed to enable database operations requiring elevated permissions. However, the vulnerability occurs when the system fails to properly verify that the user executing the trigger has the necessary permissions to perform the operations defined within the trigger function. This oversight enables attackers to install malicious triggers on tables they control, thereby gaining unauthorized access to execute code that should otherwise be restricted to privileged users.
The operational impact of this vulnerability is severe and multifaceted, as it enables authenticated attackers to escalate their privileges within the database environment. An attacker who can create tables and install triggers in a database can leverage this flaw to execute arbitrary database operations with the privileges of the trigger function owner. This could result in unauthorized data access, modification, or deletion, potentially leading to complete database compromise. The vulnerability affects multiple major PostgreSQL versions, including 8.3.x, 8.4.x, 9.0.x, and 9.1.x, making it a widespread concern for organizations maintaining legacy database installations. The attack vector requires only authenticated access to the database, which is often readily available through legitimate user accounts or compromised credentials.
Organizations should implement immediate mitigations including upgrading to patched versions of PostgreSQL where available, as the vulnerability was addressed in PostgreSQL releases 8.3.18, 8.4.11, 9.0.7, and 9.1.3 respectively. Database administrators should also review existing trigger functions marked as SECURITY DEFINER to ensure they are properly secured and that unnecessary privileges are not granted. Additional protective measures include implementing strict access controls for database users, monitoring trigger creation activities, and conducting regular security audits of database objects. This vulnerability aligns with CWE-284, which describes improper access control in software systems, and represents a clear example of privilege escalation through inadequate authorization checks. From an ATT&CK framework perspective, this vulnerability maps to privilege escalation techniques and could enable further lateral movement within database environments, making it a critical concern for cybersecurity teams responsible for database security.