CVE-2013-2001 in libXxf86vm
Summary
by MITRE
Buffer overflow in X.org libXxf86vm 1.1.2 and earlier allows X servers to cause a denial of service (crash) and possibly execute arbitrary code via crafted length or index values to the XF86VidModeGetGammaRamp function.
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Analysis
by VulDB Data Team • 05/14/2021
The vulnerability identified as CVE-2013-2001 represents a critical buffer overflow flaw within the X.org libXxf86vm library version 1.1.2 and earlier implementations. This vulnerability specifically affects the XF86VidModeGetGammaRamp function which is part of the X Window System's video mode management capabilities. The issue arises from insufficient input validation and bounds checking when processing gamma ramp data, creating a scenario where malicious X servers can manipulate the function parameters to trigger memory corruption. The flaw exists in the X.org X Window System implementation that handles video mode configuration and gamma ramp operations, which are essential components for display management in Unix-like operating systems and their derivatives.
The technical nature of this vulnerability stems from improper handling of user-supplied data within the XF86VidModeGetGammaRamp function, which operates under the Common Weakness Enumeration classification of CWE-121, which describes "Stack-based Buffer Overflow". The buffer overflow occurs when the application fails to validate the length or index values passed to the function, allowing attackers to write beyond the allocated memory boundaries. This particular implementation flaw enables attackers to craft malicious input parameters that cause the X server process to overwrite adjacent memory locations, leading to unpredictable behavior including crashes or potential code execution. The vulnerability is particularly dangerous because it operates at the X server level, which typically runs with elevated privileges and has direct access to hardware resources.
The operational impact of CVE-2013-2001 extends beyond simple denial of service scenarios to potentially enable arbitrary code execution within the context of the X server process. When exploited, this vulnerability can cause system instability through crashes and may provide attackers with a foothold for further exploitation. The X server typically runs with elevated privileges and has access to graphics hardware and display resources, making successful exploitation potentially devastating. Attackers could leverage this vulnerability to gain unauthorized access to systems, escalate privileges, or disrupt display services critical to user interfaces. The vulnerability affects systems using X.org versions prior to 1.1.3, impacting desktop environments, servers, and embedded systems that rely on X Window System for graphical operations.
Mitigation strategies for this vulnerability include immediate patching of the libXxf86vm library to version 1.1.3 or later, which contains the necessary bounds checking and input validation fixes. System administrators should also implement network segmentation to limit access to X server services and consider disabling unnecessary X11 forwarding capabilities. Additional protective measures include monitoring for suspicious X server activity and implementing intrusion detection systems that can identify malformed gamma ramp requests. The vulnerability aligns with ATT&CK technique T1059.007 for command and scripting interpreter, as exploitation may involve crafting malicious X server requests, and T1499.004 for network denial of service, as the primary impact includes system instability. Organizations should also consider implementing privilege separation mechanisms and ensuring that X server processes run with minimal required privileges to limit potential damage from successful exploitation attempts.