CVE-2013-1901 in PostgreSQL
Summary
by MITRE
PostgreSQL 9.2.x before 9.2.4 and 9.1.x before 9.1.9 does not properly check REPLICATION privileges, which allows remote authenticated users to bypass intended backup restrictions by calling the (1) pg_start_backup or (2) pg_stop_backup functions.
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Analysis
by VulDB Data Team • 05/06/2021
PostgreSQL versions 9.2.x before 9.2.4 and 9.1.x before 9.1.9 contain a critical privilege escalation vulnerability that undermines the database's replication security model. This vulnerability stems from insufficient validation of replication privileges when executing specific backup functions, creating a pathway for authenticated attackers to circumvent intended access controls. The flaw specifically affects the pg_start_backup and pg_stop_backup system functions that are typically restricted to users with appropriate replication privileges. Attackers can exploit this weakness to perform backup operations without proper authorization, effectively bypassing the database's intended security boundaries.
The technical nature of this vulnerability aligns with CWE-284, which describes improper access control mechanisms in software systems. The flaw represents a privilege escalation issue where authenticated users can gain unauthorized access to backup functionality that should be restricted to privileged replication accounts. This vulnerability operates at the database engine level where the access control checks fail to properly validate user permissions before allowing execution of critical backup functions. The absence of proper privilege verification during backup operations creates a persistent security gap that can be exploited by attackers who have established database authentication credentials but lack the specific replication permissions required for backup operations.
From an operational perspective, this vulnerability presents significant risks to database security and integrity. An attacker with basic database user access can potentially perform unauthorized backups of database content, which may include sensitive data that should remain protected from unauthorized access. The impact extends beyond simple privilege escalation as it allows for potential data exfiltration through backup operations, particularly when combined with other database access methods. The vulnerability affects organizations that rely on PostgreSQL for mission-critical applications where backup restrictions are essential for maintaining data security and compliance requirements. The attack vector requires only authenticated access to the database system, making it particularly dangerous as it can be exploited by insiders or compromised user accounts.
This vulnerability maps to several ATT&CK techniques including privilege escalation and defense evasion. The ability to bypass replication restrictions falls under T1068, which covers privilege escalation through the exploitation of software vulnerabilities. Additionally, the unauthorized backup operations can be categorized under T1070, defense evasion techniques that involve the creation of backups or copies of data to maintain access or hide malicious activities. Organizations using affected PostgreSQL versions should immediately implement mitigations including upgrading to patched versions, reviewing and tightening replication privilege assignments, and implementing additional monitoring for backup operations. The recommended approach involves applying the official PostgreSQL security patches that address the privilege validation checks in the pg_start_backup and pg_stop_backup functions, ensuring that proper access controls are enforced before allowing execution of these critical backup operations.