CVE-2015-6108 in Office
Summary
by MITRE
The Windows font library in Microsoft Windows Vista SP2; Windows Server 2008 SP2 and R2 SP1; Windows 7 SP1; Windows 8; Windows 8.1; Windows Server 2012 Gold and R2; Windows RT Gold and 8.1; Office 2007 SP3; Office 2010 SP2; Word Viewer; .NET Framework 3.0 SP2, 3.5, 3.5.1, 4, 4.5, 4.5.1, 4.5.2, and 4.6; Skype for Business 2016; Lync 2010; Lync 2013 SP1; Live Meeting 2007 Console; and Silverlight 5 allows remote attackers to execute arbitrary code via a crafted embedded font, aka "Graphics Memory Corruption Vulnerability."
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Analysis
by VulDB Data Team • 06/30/2022
The vulnerability identified as CVE-2015-6108 represents a critical graphics memory corruption flaw within the Windows font library that affects multiple versions of the Windows operating system and related Microsoft products. This vulnerability resides in the core font handling mechanisms that process embedded fonts within various applications and system components, creating a pathway for remote code execution through maliciously crafted font files. The flaw specifically targets the way Windows processes font data, particularly when handling embedded fonts in documents, web content, or application interfaces, making it a widespread concern across the Microsoft ecosystem.
Technical exploitation of this vulnerability occurs when a malicious font file is processed by the Windows font library, triggering a memory corruption condition that allows attackers to execute arbitrary code with the privileges of the targeted user. The vulnerability stems from insufficient input validation and memory management within the font processing code, which fails to properly handle malformed or specially crafted font data structures. This type of flaw falls under CWE-125, which describes out-of-bounds read conditions, and CWE-787, which covers out-of-bounds write operations, both of which are common in memory corruption vulnerabilities. The attack vector is particularly dangerous because it can be triggered through multiple entry points including email attachments, web pages, document files, and network shares.
The operational impact of CVE-2015-6108 extends far beyond individual system compromise, as it affects critical enterprise infrastructure and user endpoints across various Microsoft products and operating system versions. Attackers can leverage this vulnerability to gain unauthorized access to systems, escalate privileges, and potentially establish persistent access within networks. The vulnerability's presence in .NET Framework versions and Silverlight components means that web applications and rich internet applications are particularly at risk, as these technologies frequently process embedded fonts. Organizations running Office 2007 through Office 2016, Lync 2010 through 2013, and various Windows Server versions face significant exposure, with the potential for lateral movement and data exfiltration across network boundaries. This vulnerability aligns with ATT&CK technique T1059.007 for command and scripting interpreter, specifically PowerShell, when attackers leverage the compromised systems for further malicious activities.
Mitigation strategies for CVE-2015-6108 should encompass multiple layers of defense including immediate patch deployment for all affected Microsoft products and operating systems, network segmentation to limit attack surface, and enhanced monitoring for suspicious font processing activities. Security administrators should implement application whitelisting policies to restrict font processing in critical environments, disable unnecessary font rendering capabilities, and deploy intrusion detection systems to monitor for exploitation attempts. The vulnerability's nature as a memory corruption flaw makes it particularly susceptible to exploit mitigation techniques including address space layout randomization, data execution prevention, and heap metadata protection. Regular security assessments should focus on identifying and removing unnecessary font handling components, while security awareness training should emphasize the dangers of opening untrusted documents or visiting malicious websites that could trigger the vulnerability through embedded font processing.