CVE-2010-3959 in Windows
Summary
by MITRE
The OpenType Font (OTF) driver in Microsoft Windows XP SP2 and SP3, Windows Server 2003 SP2, Windows Vista SP1 and SP2, Windows Server 2008 Gold, SP2, and R2, and Windows 7 allows local users to gain privileges via a crafted CMAP table in an OpenType font, aka "OpenType CMAP Table Vulnerability."
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Analysis
by VulDB Data Team • 10/07/2021
The OpenType Font driver vulnerability CVE-2010-3959 represents a critical privilege escalation flaw affecting multiple versions of the microsoft windows operating system. This vulnerability specifically targets the handling of CMAP tables within OpenType font files, which are used to map character codes to glyph indices in font rendering. The flaw exists in the way windows processes these tables when loading fonts, creating a path for local attackers to execute arbitrary code with elevated privileges. The vulnerability affects windows xp service packs 2 and 3, windows server 2003 service pack 2, windows vista service packs 1 and 2, windows server 2008 gold and service pack 2, windows server 2008 r2, and windows 7 operating systems.
The technical implementation of this vulnerability stems from improper input validation within the font processing pipeline. When a windows system loads an OpenType font file containing a specially crafted CMAP table, the font driver fails to properly validate the table structure and data boundaries. This insufficient validation allows an attacker to manipulate memory layout during font processing, potentially leading to stack corruption or heap overflow conditions. The flaw specifically manifests when the system attempts to parse the CMAP table structure, which contains mapping information between character codes and glyph identifiers. Attackers can exploit this by creating malicious font files with malformed CMAP entries that cause the font driver to execute unintended code paths, ultimately enabling privilege escalation from standard user to system level privileges.
The operational impact of CVE-2010-3959 is significant as it provides local attackers with a straightforward method to elevate their privileges on affected systems. Since the vulnerability requires only local access to exploit, attackers who have already compromised a system through other means can leverage this flaw to gain full system control. This makes the vulnerability particularly dangerous in environments where users have local access to systems, as it can be exploited without requiring network connectivity or complex attack chains. The privilege escalation capability means that attackers can bypass standard security controls, modify system files, install malware, or access sensitive data that would otherwise be protected by operating system security mechanisms. The vulnerability affects a broad range of windows operating systems, making it a widespread concern for enterprise environments.
Mitigation strategies for CVE-2010-3959 focus on both immediate patching and operational security measures. Microsoft released security update ms10-061 to address this vulnerability, which should be deployed immediately across all affected systems. Organizations should also implement font restriction policies that limit the types of font files that can be loaded system-wide, particularly disabling the loading of potentially malicious font files from untrusted sources. Additional defensive measures include implementing application whitelisting to prevent execution of untrusted font processing applications, monitoring for unusual font loading activities, and ensuring that systems are regularly updated with the latest security patches. From an att&ck framework perspective, this vulnerability maps to privilege escalation techniques and can be used as part of broader attack chains to establish persistent access to target systems. Organizations should also consider implementing network segmentation to limit the potential impact of successful exploitation and maintain comprehensive monitoring to detect anomalous behavior associated with font processing activities.