CVE-2007-6428 in Xserver
Summary
by MITRE
The ProcGetReservedColormapEntries function in the TOG-CUP extension in X.Org Xserver before 1.4.1 allows context-dependent attackers to read the contents of arbitrary memory locations via a request containing a 32-bit value that is improperly used as an array index.
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Analysis
by VulDB Data Team • 08/04/2019
The vulnerability identified as CVE-2007-6428 resides within the TOG-CUP extension of X.Org Xserver version 1.4.1 and earlier, representing a critical memory safety issue that enables context-dependent attackers to access arbitrary memory locations. This flaw specifically manifests in the ProcGetReservedColormapEntries function, which processes requests related to colormap entry management within the X Window System. The vulnerability stems from improper handling of a 32-bit value that serves as an array index, creating a potential avenue for memory disclosure attacks that could compromise system security.
The technical exploitation of this vulnerability occurs through malformed requests that contain a 32-bit value which is subsequently used as an array index without proper validation or bounds checking. This improper use of the index value allows attackers to traverse memory locations beyond the intended array boundaries, potentially reading sensitive data from adjacent memory regions. The flaw represents a classic buffer over-read condition that falls under the CWE-125 vulnerability category, specifically categorized as an out-of-bounds read that can lead to information disclosure. The attack requires a context-dependent scenario where the attacker can submit malicious requests to the X server, making it particularly dangerous in multi-user environments or when X server services are exposed to untrusted networks.
The operational impact of CVE-2007-6428 extends beyond simple information disclosure, as the ability to read arbitrary memory locations can potentially expose sensitive data including authentication tokens, cryptographic keys, or other confidential information stored in memory. This vulnerability can be leveraged as part of a broader attack chain within the MITRE ATT&CK framework, specifically under the information gathering and credential access phases where adversaries seek to extract valuable data from compromised systems. The vulnerability affects systems running vulnerable X.Org Xserver versions and can be particularly impactful in environments where X11 forwarding is used or where the X server is accessible from networked clients, as these scenarios provide more attack vectors for exploitation.
Mitigation strategies for CVE-2007-6428 primarily focus on upgrading to X.Org Xserver version 1.4.1 or later, which includes the necessary patches to address the improper array index handling. System administrators should also implement network segmentation to limit access to X server services and disable unnecessary X11 forwarding capabilities. Additional protective measures include monitoring for suspicious X server requests and implementing proper access controls to restrict who can submit requests to the X server. The vulnerability highlights the importance of proper input validation and bounds checking in system-level software components, particularly in graphics and windowing systems where memory management is critical for overall system security and stability.