CVE-2017-18359 in PostGIS
Summary
by MITRE
PostGIS 2.x before 2.3.3, as used with PostgreSQL, allows remote attackers to cause a denial of service via crafted ST_AsX3D function input, as demonstrated by an abnormal server termination for "SELECT ST_AsX3D('LINESTRING EMPTY');" because empty geometries are mishandled.
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Analysis
by VulDB Data Team • 07/03/2023
The vulnerability identified as CVE-2017-18359 represents a critical denial of service flaw affecting PostGIS 2.x versions prior to 2.3.3 when integrated with PostgreSQL database systems. This vulnerability specifically targets the ST_AsX3D function, which is designed to convert geometric data into X3D (Extensible 3D) format for 3D visualization purposes. The flaw manifests when the function processes malformed or specially crafted input, particularly empty geometries, leading to abnormal server termination and complete service disruption. The vulnerability exists within the geometric processing pipeline of PostGIS, where the system fails to properly validate or handle edge cases involving empty geometries, resulting in a crash condition that affects the entire PostgreSQL instance.
The technical root cause of this vulnerability lies in inadequate input validation and error handling within the ST_AsX3D function implementation. When an attacker submits a crafted query containing an empty geometry such as "LINESTRING EMPTY", the function attempts to process this input without proper safeguards against malformed data. The system's failure to gracefully handle empty geometries results in a segmentation fault or similar critical error that terminates the PostgreSQL server process. This behavior maps directly to CWE-248, which addresses "Uncaught Exception" conditions where programs fail to handle exceptional circumstances properly, and also aligns with CWE-129, addressing "Improper Validation of Array Index" since the function likely fails to validate array bounds when processing empty geometric structures. The vulnerability demonstrates a classic lack of defensive programming practices in spatial database extensions where input sanitization and boundary condition checking are insufficient.
The operational impact of this vulnerability extends beyond simple service disruption to potentially compromise the availability of critical spatial data infrastructure. Organizations relying on PostGIS for geographic information systems, mapping applications, or spatial analytics may experience complete system outages when attackers exploit this flaw through crafted database queries. The vulnerability can be exploited remotely without authentication requirements, making it particularly dangerous in multi-tenant environments or publicly accessible database systems. The attack vector operates through standard SQL injection techniques where malicious input is passed through database queries, and the vulnerability affects any system running affected PostGIS versions regardless of underlying operating system or network configuration. This flaw can be leveraged by attackers to perform persistent denial of service attacks against spatial database services, potentially disrupting business operations, emergency response systems, or geographic data services that depend on PostgreSQL with PostGIS extensions.
Mitigation strategies for CVE-2017-18359 should prioritize immediate patching of affected PostGIS installations to version 2.3.3 or later, which contains the necessary fixes for proper empty geometry handling. Organizations should implement network-level controls including firewall rules that restrict access to database ports and limit query execution capabilities for untrusted users. Database administrators should consider implementing input validation layers and query monitoring to detect and prevent exploitation attempts. The vulnerability also highlights the importance of applying security patches promptly and maintaining updated spatial database components, as demonstrated by ATT&CK technique T1499.004 for "Endpoint Denial of Service" and T1566.001 for "Phishing via Service" where attackers might use such vulnerabilities to compromise database availability. Additional defensive measures include implementing database query timeouts, establishing robust monitoring for abnormal server termination events, and conducting regular security assessments of spatial database configurations to identify similar vulnerabilities in other geometric functions.