CVE-2015-6107 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, Windows 10 Gold and 1511, Office 2007 SP3, Office 2010 SP2, Word Viewer, Skype for Business 2016, Lync 2010, Lync 2013 SP1, and Live Meeting 2007 Console 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-2015-6107 represents a critical graphics memory corruption flaw within the Windows font library implementation across multiple operating system versions and Microsoft Office products. This vulnerability specifically affects the handling of embedded fonts within the Windows graphics subsystem, creating a pathway for remote code execution when maliciously crafted font files are processed. The flaw exists in the Windows font processing engine that manages font rendering and memory allocation, making it particularly dangerous as it can be triggered through various attack vectors including email attachments, web downloads, or network shares. The vulnerability impacts a broad range of Microsoft products and operating systems, from Windows Vista to Windows 10, as well as various Office applications and communication platforms.
The technical root cause of this vulnerability lies in improper memory handling during font processing operations, specifically within the Windows font library's memory allocation and management routines. When the system encounters a specially crafted embedded font file, the font processing code fails to properly validate memory boundaries and buffer sizes, leading to memory corruption that can be exploited to execute arbitrary code with the privileges of the affected application. This memory corruption occurs during the font rendering process when the system attempts to parse and display malicious font data, creating a classic buffer overflow scenario. The vulnerability is categorized under CWE-121 as a stack-based buffer overflow, which is particularly dangerous because it allows attackers to overwrite adjacent memory locations and potentially redirect program execution flow.
The operational impact of CVE-2015-6107 is severe and far-reaching given the widespread use of affected Microsoft products across enterprise environments. Attackers can leverage this vulnerability to gain unauthorized access to systems, execute malicious code, and potentially establish persistent backdoors. The remote exploitation capability means that attackers do not need physical access to target systems, making this vulnerability particularly attractive for large-scale attacks. The vulnerability affects not only individual users but also enterprise networks where Microsoft Office products and Windows operating systems are extensively deployed. Organizations running affected versions of Windows Server 2008, Windows 7, and Office 2010 are particularly at risk, as these products remain in use within many enterprise environments. The vulnerability's exploitation can result in complete system compromise, data exfiltration, and lateral movement within networks.
Mitigation strategies for CVE-2015-6107 should focus on immediate patch deployment and operational security measures. Microsoft released security updates that address this vulnerability through patches for all affected operating systems and Office products, which should be deployed immediately across all affected systems. Organizations should implement additional protective measures such as disabling automatic font rendering for untrusted documents, implementing application whitelisting policies, and configuring email filters to block suspicious font files. Network segmentation and monitoring for unusual font processing activities can help detect potential exploitation attempts. The vulnerability aligns with ATT&CK technique T1059.007 for Windows Command Shell and T1068 for Exploitation for Privilege Escalation, making it particularly concerning for threat actors seeking to establish persistent access. Security teams should also consider implementing sandboxing for document processing and regular vulnerability assessments to identify other potential memory corruption vulnerabilities in legacy systems.