CVE-2006-7211 in SQL Server
Summary
by MITRE
fb_lock_mgr in Firebird 1.5 uses weak permissions (0666) for the semaphore array, which allows local users to cause a denial of service (blocked query processing) by locking semaphores.
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Analysis
by VulDB Data Team • 07/08/2019
The vulnerability identified as CVE-2006-7211 affects Firebird 1.5 database management system through improper permission handling in the fb_lock_mgr component. This flaw represents a classic security misconfiguration issue where the system fails to properly restrict access permissions for critical synchronization primitives. The semaphore array utilized by the firebird database engine is created with permissions set to 0666, which grants read and write access to all users on the system. This weak permission model creates an exploitable condition where local attackers can manipulate the semaphore state to disrupt normal database operations. The vulnerability stems from a fundamental failure in privilege separation and access control implementation within the database locking mechanism, where the system does not properly enforce the principle of least privilege for system resources.
The technical execution of this vulnerability involves local users leveraging the weak semaphore permissions to acquire locks on the semaphore array, effectively blocking legitimate database queries from proceeding. When an attacker successfully locks the semaphores, the database engine enters a state where concurrent query processing becomes impossible, resulting in a denial of service condition that affects all database operations. This type of attack directly impacts the availability aspect of the CIA triad and can be classified under CWE-732 as improper permission assignment. The attack vector is local in nature, meaning that any user with access to the system can exploit this weakness, making it particularly dangerous in multi-user environments where privilege escalation is not required. The root cause lies in the lack of proper access control enforcement during resource allocation, where the system creates critical synchronization objects with overly permissive access rights.
The operational impact of CVE-2006-7211 extends beyond simple service disruption to potentially compromise database integrity and system stability. When query processing becomes blocked due to semaphore locking, legitimate database users experience complete service unavailability, which can result in significant business disruption depending on the criticality of the affected database system. This vulnerability can be exploited to cause cascading failures in applications that depend on the database, particularly in mission-critical systems where database availability is paramount. The attack can be executed with minimal privileges and technical knowledge, making it an attractive target for malicious actors who seek to disrupt services without requiring elevated access rights. From an attacker perspective, this represents a low-hanging fruit vulnerability that provides maximum impact with minimal effort, aligning with ATT&CK technique T1499.004 for network denial of service.
Mitigation strategies for this vulnerability focus on immediate permission adjustments and system hardening measures. The most direct fix involves modifying the semaphore creation process to use more restrictive permissions, typically setting permissions to 0600 or 0640 to ensure only the database process and authorized administrators can access the semaphore array. System administrators should also implement proper access control lists and privilege management to prevent unauthorized users from gaining access to database processes. Additionally, regular security audits should verify that all system resources created by database engines follow secure configuration practices. The vulnerability highlights the importance of proper resource management and access control implementation in database systems, emphasizing that even seemingly minor configuration issues can result in significant operational impacts. Organizations should also consider implementing monitoring solutions to detect unusual semaphore activity patterns that might indicate exploitation attempts, as this vulnerability can be used both intentionally and accidentally to disrupt database services.