CVE-2007-5760 in Xserver
Summary
by MITRE
Array index error in the XFree86-Misc extension in X.Org Xserver before 1.4.1 allows context-dependent attackers to execute arbitrary code via a PassMessage request containing a large array index.
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 08/04/2019
The vulnerability identified as CVE-2007-5760 represents a critical array index error within the XFree86-Misc extension of the X.Org Xserver software. This flaw exists in versions prior to 1.4.1 and constitutes a classic buffer overflow condition that can be exploited by attackers with contextual knowledge of the system. The vulnerability specifically manifests when processing PassMessage requests that contain oversized array indices, creating a scenario where memory access violations can occur. The X.Org Xserver serves as the foundational display server for Unix-like operating systems including Linux distributions, making this vulnerability particularly concerning for widespread exploitation potential. The XFree86-Misc extension provides various utility functions for X11 clients and applications, making it a legitimate target for malicious actors seeking to leverage existing system interfaces.
The technical implementation of this vulnerability stems from inadequate bounds checking within the PassMessage request handling mechanism. When an attacker crafts a malicious PassMessage request with an excessively large array index value, the Xserver fails to validate the index against the allocated array boundaries. This oversight allows the application to access memory locations beyond the intended array limits, potentially leading to memory corruption and arbitrary code execution. The flaw operates at the protocol level where X11 clients communicate with the Xserver, making it accessible through legitimate network connections or local system interfaces. According to CWE classification, this vulnerability maps to CWE-129: Improper Validation of Array Index, which specifically addresses insufficient validation of array indices that can result in out-of-bounds memory access. The vulnerability represents a direct violation of secure coding principles where input validation and boundary checks are not properly implemented.
The operational impact of CVE-2007-5760 extends significantly across multiple attack vectors and system configurations. Remote attackers capable of sending crafted X11 protocol requests to a vulnerable Xserver can potentially execute arbitrary code with the privileges of the Xserver process, which typically runs with elevated system privileges. Local exploitation scenarios are equally dangerous as attackers with access to the system can leverage this vulnerability to escalate privileges or gain unauthorized access to sensitive system resources. The vulnerability's context-dependent nature means that exploitation requires knowledge of the specific X11 environment and access to the Xserver's network interface, but once achieved, the attack can lead to complete system compromise. The ATT&CK framework categorizes this vulnerability under privilege escalation and code execution techniques, specifically mapping to T1068: Exploitation for Privilege Escalation and T1059: Command and Scripting Interpreter. The attack surface includes desktop environments, remote desktop services, and any system utilizing X11-based graphical interfaces.
Mitigation strategies for CVE-2007-5760 focus primarily on upgrading to patched versions of the X.Org Xserver software. The most effective remediation involves updating to version 1.4.1 or later, which includes proper array bounds checking and input validation mechanisms. System administrators should also implement network segmentation and firewall rules to restrict access to X11 display servers from untrusted networks. Additional protective measures include disabling unnecessary X11 extensions, implementing proper access controls, and monitoring for suspicious X11 protocol activity. The vulnerability demonstrates the critical importance of maintaining up-to-date system software and the dangers of legacy code that lacks modern security validation mechanisms. Organizations should conduct comprehensive vulnerability assessments to identify systems running vulnerable Xserver versions and prioritize patching based on risk assessment. Security monitoring solutions should be configured to detect abnormal PassMessage request patterns that may indicate exploitation attempts. The remediation process should also include reviewing system configurations to minimize the attack surface and implementing principle of least privilege for X11 service access.