CVE-2017-16612 in libXcursor
Summary
by MITRE
libXcursor before 1.1.15 has various integer overflows that could lead to heap buffer overflows when processing malicious cursors, e.g., with programs like GIMP.
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Analysis
by VulDB Data Team • 01/16/2023
The vulnerability identified as CVE-2017-16612 affects the libXcursor library version 1.1.15 and earlier, representing a critical security flaw that manifests through integer overflows leading to heap buffer overflows during cursor processing operations. This library serves as a crucial component in X Window System implementations, providing functionality for cursor image handling and manipulation across various graphical environments. The vulnerability specifically arises when processing malicious cursor files, particularly those encountered by applications such as GIMP, which rely on libXcursor for cursor management and display operations within their graphical interfaces.
The technical flaw within libXcursor stems from inadequate input validation and overflow protection mechanisms in the cursor parsing routines. When the library processes cursor files containing malformed or malicious data, integer overflows occur during calculations related to buffer sizing and memory allocation. These overflows result in heap buffer overflows, where the application writes data beyond the allocated memory boundaries, potentially corrupting adjacent memory regions and creating exploitable conditions. The vulnerability is particularly concerning because it operates at the library level, meaning any application utilizing libXcursor for cursor handling becomes susceptible to exploitation, regardless of the application's own security measures.
The operational impact of this vulnerability extends beyond simple application crashes, as heap buffer overflows can be leveraged for arbitrary code execution in certain scenarios. Attackers could craft malicious cursor files designed to trigger these integer overflows, potentially allowing them to execute malicious code with the privileges of the affected application. This presents a significant risk in environments where users might encounter untrusted cursor files or when applications process cursor data from external sources without proper validation. The vulnerability affects systems running X Window System implementations that depend on libXcursor, making it relevant to a broad range of desktop environments and graphical applications.
Mitigation strategies for CVE-2017-16612 primarily focus on updating to libXcursor version 1.1.15 or later, which includes patches addressing the integer overflow conditions. System administrators should prioritize updating their X Window System components and applications that rely on libXcursor, particularly those handling cursor data from untrusted sources. Additional protective measures include implementing strict input validation for cursor files, employing sandboxing techniques for applications processing graphical data, and monitoring for suspicious cursor file processing activities. From a cybersecurity perspective, this vulnerability aligns with CWE-190, which addresses integer overflow conditions, and could potentially map to ATT&CK techniques involving privilege escalation and code execution through memory corruption vulnerabilities. Organizations should also consider implementing network segmentation and access controls to limit exposure of systems that might process untrusted cursor data, particularly in multi-user environments where cursor files might be shared or downloaded from external sources.