CVE-2009-4136 in PostgreSQL
Summary
by MITRE
PostgreSQL 7.4.x before 7.4.27, 8.0.x before 8.0.23, 8.1.x before 8.1.19, 8.2.x before 8.2.15, 8.3.x before 8.3.9, and 8.4.x before 8.4.2 does not properly manage session-local state during execution of an index function by a database superuser, which allows remote authenticated users to gain privileges via a table with crafted index functions, as demonstrated by functions that modify (1) search_path or (2) a prepared statement, a related issue to CVE-2007-6600 and CVE-2009-3230.
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Analysis
by VulDB Data Team • 08/28/2021
This vulnerability in PostgreSQL represents a critical privilege escalation flaw that exploits improper session-local state management during index function execution. The issue affects multiple major versions of PostgreSQL from 7.4 through 8.4, specifically before the listed patch releases, creating a widespread impact across the database ecosystem. The vulnerability arises from the database's failure to properly isolate session-local state modifications when executing index functions, allowing authenticated users to manipulate the execution environment in ways that can elevate their privileges. This flaw specifically targets the interaction between index functions and session context, creating a pathway for malicious actors to exploit the database's internal state management mechanisms.
The technical exploitation occurs through crafted index functions that modify critical session parameters such as search_path or prepared statements, which are fundamental components of PostgreSQL's security model. When a superuser executes an index function, the database should maintain proper isolation of session state modifications to prevent unauthorized access to other users' data or system resources. However, in affected versions, these modifications can persist and be leveraged by attackers to gain elevated privileges. The vulnerability demonstrates a classic case of improper state management where the database fails to properly reset or isolate session parameters after executing potentially malicious index functions, creating a persistent security boundary violation.
From an operational perspective, this vulnerability poses significant risk to database environments as it allows remote authenticated users to escalate privileges without requiring physical access or additional attack vectors. The impact extends beyond simple privilege escalation to potentially enable data exfiltration, modification, or complete system compromise depending on the database's configuration and the attacker's objectives. The vulnerability's relationship to CVE-2007-6600 and CVE-2009-3230 indicates a pattern of similar session state management flaws that collectively represent a broader category of database security issues. Organizations running affected PostgreSQL versions face potential exposure to unauthorized access to sensitive data and system resources, particularly in environments where database superuser privileges are granted to multiple users or where database access controls are not properly enforced.
The mitigation strategy for this vulnerability requires immediate patching of affected PostgreSQL versions to the specified secure releases. Organizations should prioritize updating their database systems and verify that all index functions have been reviewed for potential malicious modifications. System administrators should implement comprehensive monitoring of database sessions and index function execution to detect anomalous behavior patterns that might indicate exploitation attempts. This vulnerability aligns with CWE-284 (Improper Access Control) and CWE-362 (Concurrent Execution using Shared Resource with Improper Synchronization) categories, representing a fundamental breakdown in database security boundaries. The ATT&CK framework would categorize this as a privilege escalation technique, specifically leveraging database-specific vulnerabilities to gain elevated system access. Additionally, organizations should consider implementing database activity monitoring solutions that can detect suspicious index function behavior and maintain strict access controls for database superuser accounts to minimize the potential impact of such vulnerabilities.