CVE-2009-3020 in Windows
Summary
by MITRE
win32k.sys in Microsoft Windows Server 2003 SP2 allows remote attackers to cause a denial of service (system crash) by referencing a crafted .eot file in the src descriptor of an @font-face Cascading Style Sheets (CSS) rule in an HTML document, possibly related to the Embedded OpenType (EOT) Font Engine, a different vulnerability than CVE-2006-0010, CVE-2009-0231, and CVE-2009-0232. NOTE: some of these details are obtained from third party information.
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Analysis
by VulDB Data Team • 12/08/2024
The vulnerability described in CVE-2009-3020 represents a critical flaw in the Windows kernel-mode driver win32k.sys that affects Microsoft Windows Server 2003 Service Pack 2 systems. This vulnerability specifically targets the Embedded OpenType font engine implementation within the Windows operating system, creating a remote code execution risk that can lead to system crashes and denial of service conditions. The flaw manifests when the system processes specially crafted .eot font files through the CSS @font-face directive, which is a standard web technology used to specify custom fonts in web documents. The vulnerability operates at the kernel level, making it particularly dangerous as it can be exploited without requiring local system access or user interaction beyond visiting a malicious website or viewing a specially crafted HTML document.
The technical implementation of this vulnerability involves improper input validation within the win32k.sys driver when handling font data structures. When a web browser encounters an HTML document containing a CSS @font-face rule that references a malicious .eot file, the system's font processing subsystem attempts to parse and render the embedded font data. The crafted .eot file contains malformed or oversized data structures that cause buffer overflows or memory corruption within the kernel-mode font engine. This memory corruption leads to a system crash or blue screen of death, effectively causing a denial of service condition that renders the affected Windows Server 2003 system unavailable to legitimate users. The vulnerability is classified as a heap-based buffer overflow in the font processing code, which is categorized under CWE-121 in the Common Weakness Enumeration catalog, representing heap-based buffer overflow conditions.
From an operational perspective, this vulnerability presents significant risk to enterprise environments running Windows Server 2003 systems, which were widely deployed in corporate networks during the period when this vulnerability was active. The remote exploitation nature means that attackers can trigger the vulnerability simply by hosting malicious content on a web server, making it particularly dangerous for organizations that do not maintain robust web filtering or security controls. The impact extends beyond simple denial of service as system crashes can result in data loss, service interruptions, and potential compromise of the entire server environment. Attackers can leverage this vulnerability as a precursor to more sophisticated attacks, potentially using the system instability to facilitate privilege escalation or to deploy additional malware components. The vulnerability's relationship to other font-related vulnerabilities such as CVE-2006-0010, CVE-2009-0231, and CVE-2009-0232 indicates that Microsoft was dealing with a broader class of font engine security issues that required comprehensive remediation efforts.
Organizations affected by this vulnerability should implement immediate mitigations including applying the relevant Microsoft security updates, implementing web content filtering solutions, and configuring browser security settings to restrict font loading from untrusted sources. Network administrators should also consider implementing intrusion detection systems that can identify patterns associated with malicious font file delivery and configure firewalls to block access to known malicious domains. The vulnerability demonstrates the importance of kernel-mode security in operating systems and highlights the critical need for regular security updates and patch management processes. From an ATT&CK framework perspective, this vulnerability maps to the T1059.007 technique for command and scripting interpreter, as well as T1499.004 for network denial of service, and represents a classic example of how vulnerabilities in system drivers can be exploited to achieve arbitrary code execution and system compromise. The remediation process should include not only applying the security patches but also conducting thorough security assessments of web applications and content to ensure that no malicious font files are being served to users.