CVE-2006-6102 in X.Org
Summary
by MITRE
Integer overflow in the ProcDbeGetVisualInfo function in the DBE extension for X.Org 6.8.2, 6.9.0, 7.0, and 7.1, and XFree86 X server, allows local users to execute arbitrary code via a crafted X protocol request that triggers memory corruption during processing of unspecified data structures.
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Analysis
by VulDB Data Team • 07/13/2019
The vulnerability identified as CVE-2006-6102 represents a critical integer overflow flaw within the X.Org X server's DBE (Double Buffer Extension) implementation. This vulnerability specifically affects versions 6.8.2, 6.9.0, 7.0, and 7.1 of X.Org, as well as the corresponding XFree86 X server implementations. The flaw exists within the ProcDbeGetVisualInfo function which processes X protocol requests related to visual information retrieval in the double buffering extension. This function fails to properly validate integer values during the processing of client-provided data, creating a condition where an attacker can manipulate input parameters to cause arithmetic overflow conditions that ultimately lead to memory corruption.
The technical exploitation of this vulnerability occurs when a local user crafts a malicious X protocol request that triggers the integer overflow within the ProcDbeGetVisualInfo function. When the X server processes this malformed request, the overflow corrupts memory structures that are subsequently used for further processing. This memory corruption can result in arbitrary code execution with the privileges of the X server process, which typically runs with elevated permissions to manage graphics operations and display services. The vulnerability stems from inadequate input validation and bounds checking within the X server's extension handling code, allowing attackers to manipulate the program flow through carefully constructed integer values that exceed the maximum representable value for the target data type.
From an operational perspective, this vulnerability poses significant risks to systems running affected X server implementations as it provides local users with the ability to execute arbitrary code on the target system. The attack requires local access to the system but can potentially escalate privileges to the level of the X server process, which often has extensive access to graphics resources and system capabilities. The impact extends beyond simple code execution as the memory corruption can lead to system instability, denial of service conditions, or potential privilege escalation depending on the specific system configuration and the attacker's objectives. This vulnerability particularly affects graphical environments where the X server is actively running and processing client requests, making it a serious concern for desktop environments, servers with graphical interfaces, and any system where X11 protocol services are exposed.
The vulnerability aligns with CWE-190, Integer Overflow or Wraparound, which categorizes issues where integer arithmetic results in values that exceed the maximum representable value for the data type. Additionally, this flaw maps to ATT&CK technique T1068, Exploitation for Privilege Escalation, as the successful exploitation can lead to privilege escalation within the system context. The attack surface is primarily limited to local users who can establish connections to the X server, but the potential for remote exploitation exists if the X server is configured to accept connections from untrusted networks or if other vulnerabilities exist in the X server implementation. Organizations should implement immediate mitigations including applying the vendor-provided patches, restricting local access to X server processes, and monitoring for suspicious X protocol activity that might indicate exploitation attempts.
Mitigation strategies for this vulnerability should focus on immediate patch application to address the root cause in the X server implementation. System administrators should also implement access controls that limit local user access to X server resources and consider disabling unnecessary X extensions where possible. Network segmentation and firewall rules can help prevent unauthorized access to X server ports while monitoring solutions should be deployed to detect anomalous X protocol activity. The vulnerability underscores the importance of proper input validation and integer overflow protection in server-side applications, particularly those handling user-provided data through network protocols. Organizations should also conduct security assessments of their X server configurations to identify and remediate any additional vulnerabilities that may compound the risk posed by this integer overflow condition.