CVE-2018-0761 in Windows
Summary
by MITRE
The Microsoft Windows Embedded OpenType (EOT) font engine in Microsoft Windows 7 SP1 and Windows Server 2008 R2 allows information disclosure, due to how the Windows EOT font engine handles embedded fonts, aka "Windows EOT Font Engine Information Disclosure Vulnerability". This CVE ID is unique from CVE-2018-0755, CVE-2018-0760, and CVE-2018-0855.
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Analysis
by VulDB Data Team • 02/03/2021
The vulnerability identified as CVE-2018-0761 represents a critical information disclosure flaw within the Microsoft Windows Embedded OpenType (EOT) font engine that affects Windows 7 Service Pack 1 and Windows Server 2008 R2 systems. This vulnerability stems from improper handling of embedded font data within the EOT format, creating a security risk that could potentially expose sensitive system information to unauthorized parties. The flaw specifically resides in how the Windows EOT font engine processes and interprets embedded font resources, making it susceptible to information leakage through malformed or specially crafted font files. The vulnerability is classified under CWE-200, which represents "Information Exposure" in the Common Weakness Enumeration catalog, indicating that the flaw allows for unauthorized information disclosure that could reveal system internals or sensitive data.
The technical exploitation of this vulnerability occurs when a malicious actor presents a specially crafted EOT font file to a vulnerable system. The EOT font engine fails to properly validate or sanitize the embedded font data, leading to information disclosure through memory corruption or improper memory access patterns. This type of vulnerability typically falls under the ATT&CK framework's T1059.007 technique, which involves the use of scripting languages, but in this case represents a more fundamental system-level information disclosure issue. The flaw allows attackers to potentially extract memory contents, system pointers, or other sensitive information that could aid in further exploitation attempts or system compromise. The vulnerability's impact extends beyond simple information disclosure as it provides attackers with additional reconnaissance data that could be leveraged in more sophisticated attacks.
The operational impact of CVE-2018-0761 is significant for organizations running affected Windows versions, as it creates a potential attack vector that could be exploited in various scenarios including social engineering campaigns, drive-by downloads, or targeted attacks. The vulnerability's nature means that any application or process that processes EOT fonts could potentially be exploited, including web browsers, email clients, or document processing applications. Organizations with legacy systems running Windows 7 SP1 or Windows Server 2008 R2 are particularly at risk since these systems are no longer receiving regular security updates from Microsoft. The information disclosure could potentially reveal system memory layouts, pointer values, or other sensitive data that could aid in bypassing security mechanisms such as address space layout randomization or data execution prevention. This makes the vulnerability particularly dangerous in environments where attackers are attempting to develop more sophisticated exploits or conduct advanced persistent threats.
Mitigation strategies for CVE-2018-0761 should prioritize immediate patching of affected systems, although organizations should note that Windows 7 SP1 and Windows Server 2008 R2 have reached end-of-life status, making official patches unavailable. Organizations should implement network-based restrictions to prevent processing of EOT font files from untrusted sources, particularly in web browsers and email applications. Security controls such as application whitelisting, sandboxing of font processing applications, and monitoring for unusual font processing activity should be implemented. Additionally, organizations should consider implementing network segmentation to limit the potential impact of exploitation and establish monitoring procedures to detect potential information disclosure attempts. The vulnerability highlights the importance of maintaining up-to-date systems and proper security hygiene, as legacy systems often contain unpatched vulnerabilities that create persistent security risks for organizations.