CVE-2010-4698 in PHP
Summary
by MITRE
Stack-based buffer overflow in the GD extension in PHP before 5.2.15 and 5.3.x before 5.3.4 allows context-dependent attackers to cause a denial of service (application crash) via a large number of anti-aliasing steps in an argument to the imagepstext function.
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Analysis
by VulDB Data Team • 10/12/2021
The vulnerability CVE-2010-4698 represents a critical stack-based buffer overflow within the GD extension of PHP, affecting versions prior to 5.2.15 and 5.3.4. This flaw resides in the imagepstext function which processes PostScript text rendering operations and specifically manifests when handling an excessive number of anti-aliasing steps. The vulnerability operates through a classic stack memory corruption mechanism where insufficient bounds checking allows attackers to overwrite adjacent memory locations on the stack, potentially leading to application instability or complete crash.
The technical exploitation of this vulnerability occurs when the GD extension processes user-supplied input through the imagepstext function without adequate validation of anti-aliasing step parameters. When an attacker provides an excessive number of anti-aliasing steps, the function allocates insufficient stack space to accommodate the operation, causing the buffer to overflow. This type of vulnerability falls under CWE-121 Stack-based Buffer Overflow, which is classified as a fundamental memory safety issue where data written to a buffer exceeds the allocated stack space. The attack vector is context-dependent, meaning that the vulnerability requires specific conditions to be met, typically involving web applications that process user input through PHP's GD extension for image manipulation tasks.
The operational impact of CVE-2010-4698 extends beyond simple denial of service to potentially enable more sophisticated attack scenarios. While the primary effect is application crash and service disruption, the stack corruption could theoretically be exploited to execute arbitrary code if proper exploit mitigation controls are absent. The vulnerability affects web applications that utilize PHP's GD library for image processing, particularly those handling user-uploaded content or dynamic image generation. In environments where PHP applications process untrusted input through imagepstext operations, this vulnerability creates a significant risk of service availability disruption and could be leveraged as part of broader attack chains targeting web application infrastructure.
Mitigation strategies for this vulnerability must focus on immediate version upgrades to PHP 5.2.15 or 5.3.4, which contain the necessary patches to address the buffer overflow condition. Organizations should also implement input validation controls to limit the number of anti-aliasing steps processed by the imagepstext function, establishing reasonable upper bounds on user-supplied parameters. Additionally, deployment of web application firewalls and runtime application self-protection mechanisms can provide additional layers of defense against exploitation attempts. The vulnerability demonstrates the importance of proper input validation and memory management in extension modules, aligning with ATT&CK technique T1059.007 for command and scripting interpreter to prevent exploitation of memory corruption vulnerabilities through controlled input parameters and proper bounds checking implementation.