CVE-2015-8874 in PHP
Summary
by MITRE
Stack consumption vulnerability in GD in PHP before 5.6.12 allows remote attackers to cause a denial of service via a crafted imagefilltoborder call.
If you want to get the best quality for vulnerability data then you always have to consider VulDB.
Analysis
by VulDB Data Team • 08/19/2022
The vulnerability identified as CVE-2015-8874 represents a critical stack consumption issue within the GD graphics library implementation in PHP versions prior to 5.6.12. This flaw specifically manifests during the processing of imagefilltoborder function calls, where maliciously crafted image data can trigger excessive stack memory consumption. The vulnerability falls under the category of denial of service attacks, as it allows remote attackers to exhaust system resources and potentially crash the affected PHP application or server instance. The GD library serves as a fundamental component for image processing in PHP applications, making this vulnerability particularly dangerous as it can affect numerous web applications that rely on image manipulation capabilities.
The technical root cause of this vulnerability stems from inadequate input validation and memory management within the imagefilltoborder function implementation. When processing specially crafted image data, the function fails to properly limit stack usage during recursive operations or deep processing loops, leading to unbounded stack consumption. This behavior aligns with CWE-772, which describes insufficient resource management, and specifically relates to stack overflow conditions that occur during uncontrolled recursive operations. The vulnerability is particularly concerning because it operates at the library level rather than application level, meaning that any PHP application utilizing the GD library and processing user-provided image data becomes susceptible to this attack vector.
The operational impact of CVE-2015-8874 extends beyond simple service disruption to potentially compromise entire server environments. Remote attackers can exploit this vulnerability by uploading or providing malicious image files that trigger the vulnerable imagefilltoborder function, causing the target system to consume excessive stack memory until the process terminates or system resources are exhausted. This attack vector is particularly dangerous in multi-tenant hosting environments or web applications that accept user uploads, as it can be used to systematically degrade service availability. The vulnerability also maps to ATT&CK technique T1499.004, which covers network denial of service attacks, and represents a classic example of resource exhaustion attacks that can be amplified through automated exploitation tools.
Mitigation strategies for CVE-2015-8874 primarily focus on immediate software updates and defensive programming practices. The most effective solution involves upgrading PHP installations to version 5.6.12 or later, where the stack consumption issue has been addressed through improved input validation and memory management controls. System administrators should also implement strict image validation measures, including file type checking, size limitations, and content scanning before processing any user-uploaded images. Additionally, implementing resource limits and monitoring for abnormal stack usage patterns can help detect and prevent exploitation attempts. Organizations should consider deploying web application firewalls that can identify and block suspicious image processing requests, while also establishing robust logging and alerting mechanisms to monitor for potential exploitation attempts. The vulnerability demonstrates the importance of maintaining up-to-date software libraries and implementing comprehensive security testing procedures that include both static and dynamic analysis of third-party components.