CVE-2007-1003 in X11
Summary
by MITRE
Integer overflow in ALLOCATE_LOCAL in the ProcXCMiscGetXIDList function in the XC-MISC extension in the X.Org X11 server (xserver) 7.1-1.1.0, and other versions before 20070403, allows remote authenticated users to execute arbitrary code via a large expression, which results in memory corruption.
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Analysis
by VulDB Data Team • 07/17/2019
The vulnerability described in CVE-2007-1003 represents a critical integer overflow condition within the X.Org X11 server implementation that exposes systems to remote code execution attacks. This flaw exists in the ProcXCMiscGetXIDList function of the XC-MISC extension, which is part of the X11 server software that manages graphical user interfaces in Unix-like operating systems. The vulnerability specifically affects versions 7.1 through 1.1.0 of the X.Org server, with the issue being resolved in versions released after April 3, 2007. The flaw occurs during memory allocation operations when processing large expressions, creating a scenario where integer arithmetic overflows result in improper memory handling.
The technical mechanism behind this vulnerability involves the ALLOCATE_LOCAL function within the XC-MISC extension that processes XID (X11 Identifier) lists. When a remote authenticated user sends a specially crafted request with a large expression parameter, the system performs integer arithmetic to calculate memory allocation requirements. Due to insufficient bounds checking and overflow protection, the calculation results in an integer overflow where the intended memory allocation size becomes significantly smaller than required, leading to heap corruption. This memory corruption creates exploitable conditions that allow attackers to manipulate memory layout and potentially execute arbitrary code with the privileges of the X server process.
The operational impact of this vulnerability extends beyond simple privilege escalation, as it provides attackers with a pathway to compromise entire graphical environments and potentially underlying system resources. Since X11 servers typically run with elevated privileges to manage hardware access and graphical operations, successful exploitation could lead to complete system compromise. The vulnerability affects systems using X.Org X11 server implementations across multiple Unix-like platforms including Linux distributions and various BSD variants. Network-based attacks are possible since the vulnerability can be triggered through authenticated X11 connections, making it particularly dangerous in multi-user environments or systems exposed to untrusted networks.
This vulnerability aligns with CWE-190, which specifically addresses integer overflow conditions, and demonstrates characteristics consistent with the ATT&CK technique T1068, which involves exploiting legitimate credentials to gain system access. The flaw represents a classic buffer overflow scenario where improper integer handling leads to memory corruption, making it a prime target for exploitation frameworks. Organizations should implement immediate patch management procedures to update X.Org X11 server implementations to versions released after April 3, 2007, which contain the necessary fixes for integer overflow protection. Additionally, network segmentation and access controls should be implemented to limit exposure of X11 services to untrusted networks, while monitoring for anomalous X11 traffic patterns that might indicate exploitation attempts. System administrators should also consider disabling unnecessary X11 extensions and implementing proper authentication mechanisms to reduce the attack surface available to potential adversaries.