CVE-2017-8695 in Windows
Summary
by MITRE
Windows Uniscribe in Microsoft Windows Server 2008 SP2 and R2 SP1; Windows 7 SP1; Windows 8.1; Windows Server 2012 Gold and R2; Windows RT 8.1; Windows 10 Gold, 1511, 1607, 1703, and Server 2016; Office 2007 SP3; Office 2010 SP2; Word Viewer; Office for Mac 2011 and 2016; Skype for Business 2016; Lync 2013 SP1; Lync 2010; Lync 2010 Attendee; and Live Meeting 2007 Add-in and Console allows an attacker to obtain information to further compromise a user's system via a specially crafted document or an untrusted webpage, aka "Graphics Component Information Disclosure Vulnerability."
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Analysis
by VulDB Data Team • 01/12/2021
The vulnerability identified as CVE-2017-8695 represents a critical information disclosure flaw within Microsoft's Uniscribe text processing engine that affects multiple versions of Windows operating systems and Office applications. This vulnerability specifically resides in the graphics component handling mechanism that processes complex text rendering operations, particularly those involving Unicode text processing and font rendering. The flaw enables attackers to exploit the text rendering subsystem through carefully crafted documents or web content that triggers improper memory handling during text processing operations, potentially exposing sensitive memory contents to unauthorized parties.
The technical exploitation of this vulnerability occurs when Uniscribe processes malformed or specially crafted text elements within documents or web pages, leading to improper memory management that can result in information leakage. This type of vulnerability falls under the CWE-200 category of "Information Exposure" and represents a classic example of how text processing components can become attack vectors for information disclosure attacks. The vulnerability stems from inadequate bounds checking and memory management within the Uniscribe engine's handling of complex text rendering scenarios, particularly when processing Unicode text with specific font characteristics and layout properties.
The operational impact of CVE-2017-8695 extends beyond simple information disclosure, as the leaked memory contents can contain sensitive data such as stack pointers, heap addresses, or other system information that attackers can leverage for more sophisticated attacks. This vulnerability can be exploited through multiple attack vectors including malicious Word documents, HTML pages, or Office files that trigger the problematic text rendering code path. The attack surface is particularly broad given that the affected components are present in numerous Microsoft products including Windows Server 2008, Windows 7, Office 2007 through 2016, and various Skype for Business and Lync versions. Security researchers have classified this vulnerability as a medium to high severity issue that can potentially enable privilege escalation or further compromise of affected systems.
Mitigation strategies for this vulnerability should include immediate deployment of Microsoft security patches and updates that address the specific memory handling issues within the Uniscribe component. Organizations should implement network segmentation and content filtering to prevent users from accessing untrusted documents or web content that could trigger this vulnerability. The ATT&CK framework categorizes this vulnerability under the "Tactic: Defense Evasion" and "Technique: Exploitation for Privilege Escalation" categories, as attackers can leverage information disclosure to gain insights into system memory layouts for subsequent attacks. Additionally, administrators should consider implementing Application Control policies to restrict access to vulnerable applications and ensure that all systems are running patched versions of the affected software components. The vulnerability demonstrates the importance of proper memory management in text processing libraries and highlights the need for comprehensive security testing of core system components that handle user-provided content.