CVE-2015-9262 in libXcursor
Summary
by MITRE
_XcursorThemeInherits in library.c in libXcursor before 1.1.15 allows remote attackers to cause denial of service or potentially code execution via a one-byte heap overflow.
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Analysis
by VulDB Data Team • 04/28/2023
The vulnerability identified as CVE-2015-9262 affects the libXcursor library version 1.1.14 and earlier, representing a critical heap overflow condition that can be exploited remotely to cause denial of service or potentially achieve arbitrary code execution. This flaw exists within the XcursorThemeInherits function located in the library.c file of the affected library, which is part of the X Window System's cursor handling components. The vulnerability stems from improper bounds checking during the processing of cursor theme files, specifically when parsing inheritance relationships between different cursor themes. The one-byte heap overflow occurs when the library attempts to write data beyond the allocated memory boundaries, creating a condition that can be manipulated by remote attackers to corrupt adjacent memory locations.
The technical nature of this vulnerability places it under CWE-121, heap-based buffer overflow, which is a well-documented class of memory corruption vulnerabilities that can lead to system instability or unauthorized code execution. The attack vector requires remote exploitation through malformed cursor theme files that are processed by applications using the vulnerable libXcursor library. This vulnerability affects a wide range of applications and systems that rely on X Window System cursor handling functionality, including desktop environments, window managers, and various graphical applications that process cursor themes. The impact extends beyond simple denial of service to potentially allow remote code execution, making it particularly dangerous in environments where untrusted cursor data might be processed.
Operational impact of CVE-2015-9262 is significant across multiple attack surfaces within the X Window System ecosystem. Systems that process user-provided cursor themes or download cursor packages from untrusted sources become vulnerable to exploitation, including web browsers that might render cursor themes, desktop environments that support dynamic cursor theme switching, and any application that utilizes the libXcursor library for cursor handling. The vulnerability can be exploited through various means including malicious websites, email attachments, or file sharing platforms that distribute cursor theme files. According to ATT&CK framework category T1203, this vulnerability falls under the technique of "Exploitation for Client Execution" where adversaries leverage software vulnerabilities to execute arbitrary code on target systems. The remote nature of the exploit means that attackers do not require local system access or user interaction beyond the normal processing of cursor theme files.
Mitigation strategies for CVE-2015-9262 primarily involve upgrading to libXcursor version 1.1.15 or later, which contains the necessary patches to address the heap overflow condition. System administrators should prioritize patching affected systems, particularly those running X Window System environments with applications that process cursor themes from untrusted sources. Additional protective measures include implementing strict file validation for cursor theme files, restricting access to cursor theme processing functions, and monitoring for unusual memory allocation patterns that might indicate exploitation attempts. The vulnerability also highlights the importance of proper input validation and memory management practices in graphical system libraries, as recommended by security standards such as the OWASP Top Ten and NIST cybersecurity guidelines. Organizations should also consider implementing network segmentation and access controls to limit the potential impact of exploitation, particularly in environments where cursor theme processing occurs automatically or in response to user interactions with web content.