CVE-2017-9773 in Horde_Image
Summary
by MITRE
Denial of Service was found in Horde_Image 2.x before 2.5.0 via a crafted URL to the "Null" image driver.
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Analysis
by VulDB Data Team • 10/19/2019
The vulnerability identified as CVE-2017-9773 represents a denial of service condition affecting Horde_Image version 2.x prior to 2.5.0. This issue specifically manifests when the application processes a crafted URL through the "Null" image driver component. The affected system operates within the broader context of web-based content management and image processing frameworks where Horde_Image serves as a core library for handling various image operations. The vulnerability stems from inadequate input validation and sanitization mechanisms within the image driver selection process, creating an exploitable path where maliciously constructed URLs can trigger unexpected application behavior.
The technical flaw resides in the improper handling of URL parameters when the Null image driver is invoked. When a user submits a URL containing specific malformed or crafted parameters, the Horde_Image library fails to properly validate these inputs before attempting to process them through the Null driver. This driver is typically intended for testing or debugging purposes but can be exploited when accessible in production environments. The vulnerability creates a condition where the application enters an infinite loop or consumes excessive system resources, ultimately leading to service unavailability. The flaw operates at the input processing layer and demonstrates a classic lack of proper parameter validation that allows arbitrary code execution paths to be triggered through seemingly benign user input.
The operational impact of this vulnerability extends beyond simple service disruption to encompass potential system resource exhaustion and application instability. When exploited, the crafted URL causes the application to consume excessive CPU cycles or memory resources, effectively rendering the affected service unavailable to legitimate users. This denial of service condition can be particularly damaging in production environments where image processing capabilities are critical to application functionality. Attackers can leverage this vulnerability to perform sustained denial of service attacks, potentially causing cascading failures in systems that depend on Horde_Image for image handling operations. The vulnerability affects not only individual applications but also the broader ecosystem of systems that utilize the Horde framework for web-based content management.
Mitigation strategies for CVE-2017-9773 focus primarily on upgrading to the patched version of Horde_Image 2.5.0 or later, which implements proper input validation and sanitization for URL parameters. Organizations should also implement network-level controls to restrict access to image processing endpoints and establish robust input validation mechanisms at all application layers. The implementation of proper access controls and authentication measures can help prevent unauthorized exploitation of the Null driver component. Additionally, security monitoring should be enhanced to detect unusual patterns of image processing requests that may indicate exploitation attempts. This vulnerability aligns with CWE-20, representing a weakness in input validation that allows for denial of service conditions. From an ATT&CK framework perspective, this represents a technique for service disruption and resource exhaustion that could be part of broader attack campaigns targeting web application availability. Organizations should also consider implementing web application firewalls and regular security assessments to identify and remediate similar vulnerabilities across their application portfolios.