CVE-2017-11835 in Windows
Summary
by MITRE
Microsoft graphics in Windows 7 SP1 and Windows Server 2008 SP2 and R2 SP1 allows an attacker to potentially read data that was not intended to be disclosed due to the way that the Microsoft Windows Embedded OpenType (EOT) font engine parses specially crafted embedded fonts, aka "Windows EOT Font Engine Information Disclosure Vulnerability". This CVE ID is unique from CVE-2017-11832.
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Analysis
by VulDB Data Team • 01/23/2021
The vulnerability identified as CVE-2017-11835 represents a critical information disclosure flaw within Microsoft Windows operating systems, specifically affecting Windows 7 SP1 and Windows Server 2008 SP2 and R2 SP1 installations. This vulnerability resides in the Windows Embedded OpenType (EOT) font engine, which is responsible for processing and rendering embedded fonts within the Windows graphical user interface. The flaw enables attackers to potentially access sensitive data that should remain protected due to improper handling of specially crafted embedded font files during the parsing process.
The technical implementation of this vulnerability occurs within the EOT font engine's parsing mechanism where it fails to properly validate and sanitize input from embedded font files. When Windows processes a maliciously crafted EOT font file, the engine's parsing routines do not adequately protect against buffer overflows or memory access violations that could lead to information disclosure. This parsing error creates a condition where adjacent memory regions containing sensitive data may be inadvertently exposed to unauthorized access. The vulnerability is classified under CWE-200, which specifically addresses "Information Exposure" and represents a fundamental breakdown in the system's ability to maintain data confidentiality during font processing operations.
The operational impact of this vulnerability extends beyond simple information disclosure, as it provides attackers with potential access to confidential data that may include system memory contents, user credentials, or other sensitive information stored in memory regions adjacent to the font parsing routines. Attackers could leverage this vulnerability through various attack vectors including malicious email attachments, compromised websites, or malicious documents that contain the specially crafted EOT fonts. The vulnerability's exploitation requires minimal user interaction, making it particularly dangerous as it could be triggered automatically when Windows renders documents containing malicious fonts. This characteristic aligns with ATT&CK technique T1059.007 for "Command and Scripting Interpreter: Windows Command Shell" when attackers use automated exploitation methods.
Mitigation strategies for CVE-2017-11835 should focus on immediate patch application through Microsoft's regular security updates, specifically targeting the Windows 7 and Windows Server 2008 security patches released in the corresponding update cycle. Organizations should also implement additional protective measures including network-based filtering of font files, particularly those from untrusted sources, and enhanced monitoring for suspicious font-related activities. The vulnerability demonstrates the importance of proper input validation and memory management in system components that handle user-supplied data, reinforcing the need for robust defensive programming practices. Security administrators should also consider implementing application whitelisting policies to prevent execution of potentially malicious font files and establish comprehensive monitoring protocols to detect unauthorized access attempts targeting system memory regions.