CVE-2018-20803 in MongoDB
Summary
by MITRE • 11/23/2020
A user authorized to perform database queries may trigger denial of service by issuing specially crafted queries, which loop indefinitely in mathematics processing while retaining locks. This issue affects: MongoDB Inc. MongoDB Server v4.0 versions prior to 4.0.5; v3.6 versions prior to 3.6.10; v3.4 versions prior to 3.4.19.
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Analysis
by VulDB Data Team • 09/16/2024
This vulnerability represents a critical denial of service flaw in mongodb server implementations that allows authenticated users to exploit mathematical processing loops while maintaining database locks. The issue manifests when legitimate database users submit specially crafted queries that trigger infinite loops during mathematical computations, causing the database to become unresponsive while holding onto active locks. The vulnerability specifically impacts mongodb server versions prior to the mentioned patches, with the most affected versions being 4.0.x before 4.0.5, 3.6.x before 3.6.10, and 3.4.x before 3.4.19. This represents a classic example of a resource exhaustion attack where computational resources are consumed indefinitely while maintaining database lock states.
The technical flaw stems from insufficient input validation and loop detection mechanisms within the mongodb query processing engine when handling mathematical operations. When users submit queries containing malformed mathematical expressions or recursive operations, the server's mathematical processing engine enters into infinite loops while still maintaining active locks on database resources. This creates a scenario where legitimate database operations cannot proceed because locks remain held indefinitely, effectively blocking all other database access. The vulnerability is particularly dangerous because it requires only authenticated access to exploit, meaning that any user with database query permissions can trigger this condition. From a cybersecurity perspective, this vulnerability aligns with CWE-835 which addresses infinite loops in software systems, and represents a significant operational risk that can be leveraged for denial of service attacks.
The operational impact of this vulnerability extends beyond simple service disruption to create cascading effects throughout database operations and application availability. When the database becomes unresponsive due to these infinite loops, it affects all applications and services that depend on the database, potentially leading to widespread system outages. The locked database resources prevent other legitimate queries from executing, creating a denial of service condition that can persist until the database process is manually restarted. Organizations using affected mongodb versions face significant risk of operational disruption, especially in environments where database availability is critical for business operations. The vulnerability also poses challenges for monitoring and incident response since the symptoms appear as database unresponsiveness rather than obvious malicious activity.
Organizations should immediately implement mitigations including applying the available patches for mongodb server versions, with the most critical updates being 4.0.5, 3.6.10, and 3.4.19. System administrators should also implement query monitoring and resource limiting mechanisms to detect and prevent potentially malicious query patterns. Database access controls should be reviewed to ensure that only necessary users have query permissions, reducing the attack surface for this vulnerability. Network segmentation and database firewalls can help limit the impact of potential exploitation by restricting access to database servers. Additionally, implementing comprehensive monitoring solutions that can detect unusual query processing patterns and lock contention will help identify exploitation attempts before they cause significant disruption. The vulnerability demonstrates the importance of proper input validation and resource management in database systems, aligning with ATT&CK technique T1499 which covers denial of service attacks targeting database systems.