CVE-2013-1997 in libX11
Summary
by MITRE
Multiple buffer overflows in X.org libX11 1.5.99.901 (1.6 RC1) and earlier allow X servers to cause a denial of service (crash) and possibly execute arbitrary code via crafted length or index values to the (1) XAllocColorCells, (2) _XkbReadGetDeviceInfoReply, (3) _XkbReadGeomShapes, (4) _XkbReadGetGeometryReply, (5) _XkbReadKeySyms, (6) _XkbReadKeyActions, (7) _XkbReadKeyBehaviors, (8) _XkbReadModifierMap, (9) _XkbReadExplicitComponents, (10) _XkbReadVirtualModMap, (11) _XkbReadGetNamesReply, (12) _XkbReadGetMapReply, (13) _XimXGetReadData, (14) XListFonts, (15) XListExtensions, and (16) XGetFontPath functions.
If you want to get best quality of vulnerability data, you may have to visit VulDB.
Analysis
by VulDB Data Team • 05/14/2021
The vulnerability identified as CVE-2013-1997 represents a critical buffer overflow issue affecting the X.org libX11 library version 1.5.99.901 and earlier releases. This flaw exists within the core X Window System client library that handles communication between X clients and X servers, making it a fundamental component in graphical user interface operations across Unix-like systems. The vulnerability stems from insufficient input validation in multiple functions that process data from X servers, creating opportunities for malicious actors to exploit memory corruption through crafted data sequences.
The technical implementation of this vulnerability manifests through several specific functions within the libX11 library that handle various X protocol operations. The affected functions include XAllocColorCells, _XkbReadGetDeviceInfoReply, _XkbReadGeomShapes, and numerous other XKB (X Keyboard Extension) related functions that process keyboard geometry and mapping data. These functions fail to properly validate length or index parameters provided by X servers, allowing attackers to supply oversized or malformed data that exceeds allocated buffer boundaries. The flaw operates at the memory management level where insufficient bounds checking permits data to overwrite adjacent memory locations, potentially leading to stack corruption or heap corruption depending on the specific function exploited.
From an operational perspective, this vulnerability creates significant security implications for systems relying on X Window System functionality. The potential for denial of service through system crashes represents an immediate concern, as any X server connection could trigger application instability and require system restarts. More critically, the possibility of arbitrary code execution means that malicious actors could potentially gain control over affected systems, particularly when X servers are running with elevated privileges or when the X11 forwarding mechanisms are exploited in remote access scenarios. The vulnerability affects a broad range of applications that depend on libX11, from desktop environments to server applications that utilize X11 protocols for display management.
The attack surface for this vulnerability is extensive given that X11 is fundamental to graphical interfaces in Unix-like systems, including Linux distributions, BSD variants, and various enterprise environments. Systems utilizing X11 forwarding for remote desktop access, virtual desktop environments, or X server implementations that accept untrusted input from remote hosts present particularly high-risk scenarios. The vulnerability aligns with CWE-121, which describes stack-based buffer overflow conditions, and CWE-122, which covers heap-based buffer overflow conditions. From an ATT&CK framework perspective, this vulnerability maps to T1059 for command execution through compromised X server connections and T1499 for denial of service attacks targeting system resources.
Mitigation strategies for CVE-2013-1997 require immediate system updates to libX11 versions that contain patches addressing the buffer overflow conditions. Organizations should implement network segmentation to limit X server access to trusted hosts and disable unnecessary X11 forwarding capabilities in remote access solutions. Security monitoring should focus on detecting unusual X server activity or connection patterns that might indicate exploitation attempts. Additionally, implementing proper input validation at the application level and utilizing address space layout randomization (ASLR) and stack canaries can provide additional protection layers. System administrators should also consider restricting X server privileges and implementing proper access controls for X11 connections to minimize the impact of potential exploitation. The vulnerability demonstrates the critical importance of maintaining updated graphics libraries and implementing proper security controls in X Window System environments.