CVE-2013-1982 in Secure Global Desktop
Summary
by MITRE
Multiple integer overflows in X.org libXext 1.3.1 and earlier allow X servers to trigger allocation of insufficient memory and a buffer overflow via vectors related to the (1) XcupGetReservedColormapEntries, (2) XcupStoreColors, (3) XdbeGetVisualInfo, (4) XeviGetVisualInfo, (5) XShapeGetRectangles, and (6) XSyncListSystemCounters functions.
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Analysis
by VulDB Data Team • 12/20/2020
The vulnerability identified as CVE-2013-1982 represents a critical security flaw within the X.org libXext library version 1.3.1 and earlier, affecting the core X Window System implementation used across Unix-like operating systems. This vulnerability stems from multiple integer overflow conditions that occur during memory allocation operations within several X protocol functions, creating a pathway for malicious X servers to manipulate memory structures and potentially execute arbitrary code. The affected functions include XcupGetReservedColormapEntries, XcupStoreColors, XdbeGetVisualInfo, XeviGetVisualInfo, XShapeGetRectangles, and XSyncListSystemCounters, all of which handle different aspects of X server communication and resource management.
The technical exploitation of this vulnerability occurs when X servers process client requests containing malformed parameters that trigger integer overflow conditions during memory allocation calculations. When these integer overflows occur, they result in insufficient memory being allocated for buffer operations, leading to buffer overflow conditions that can be leveraged by attackers to overwrite adjacent memory locations. This type of vulnerability falls under CWE-190, Integer Overflow or Wraparound, which is a common class of memory safety issues that can lead to arbitrary code execution. The flaw specifically demonstrates how improper input validation and integer arithmetic handling can create exploitable conditions in networked X server implementations where trusted client connections are assumed.
The operational impact of CVE-2013-1982 extends beyond simple denial of service scenarios, as it can potentially enable remote code execution on systems running vulnerable X server implementations. Attackers who can establish connections to X servers with this vulnerability can craft malicious X protocol requests that cause the server to allocate insufficient memory, leading to buffer overflows that may allow privilege escalation or arbitrary code execution. This vulnerability particularly affects systems where X server processes run with elevated privileges, as the exploitation can potentially lead to complete system compromise. The attack surface includes desktop environments, server installations, and any system running X Window System implementations that utilize the vulnerable libXext library functions.
Mitigation strategies for this vulnerability should focus on immediate library updates to versions containing fixes for the integer overflow conditions, as well as implementing network-level security measures to restrict access to X servers from untrusted sources. System administrators should ensure that X server implementations are configured with proper access controls and that only authorized clients can establish connections to X servers. The implementation of Address Space Layout Randomization (ASLR) and stack canaries can provide additional protection layers against exploitation attempts, though these are not comprehensive solutions for integer overflow vulnerabilities. Organizations should also consider implementing network segmentation and firewall rules to limit X server exposure, particularly in environments where X server access is not strictly required for legitimate operations, aligning with ATT&CK technique T1068 for privilege escalation and T1190 for exploitation of remote services.