CVE-2009-0231 in Windows
Summary
by MITRE
The Embedded OpenType (EOT) Font Engine (T2EMBED.DLL) in Microsoft Windows 2000 SP4, XP SP2 and SP3, Server 2003 SP2, Vista Gold, SP1, and SP2, and Server 2008 Gold and SP2 allows remote attackers to execute arbitrary code via a crafted name table in a data record that triggers an integer truncation and a heap-based buffer overflow, aka "Embedded OpenType Font Heap Overflow Vulnerability."
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Analysis
by VulDB Data Team • 03/17/2021
The CVE-2009-0231 vulnerability represents a critical heap-based buffer overflow in Microsoft Windows' Embedded OpenType font engine component known as T2EMBED.DLL. This flaw exists within the font processing pipeline that handles EOT font files, which are used to display text in Windows operating systems. The vulnerability specifically manifests when the system encounters a maliciously crafted name table within an EOT font data record, creating a dangerous condition that can be exploited remotely by attackers to execute arbitrary code on affected systems. The flaw affects a broad range of Microsoft Windows versions including Windows 2000 SP4, XP SP2 and SP3, Server 2003 SP2, Vista Gold, SP1, and SP2, as well as Server 2008 Gold and SP2, making it particularly concerning given the widespread deployment of these operating systems across enterprise environments. This vulnerability operates at the intersection of font rendering and memory management, where an integer truncation error leads to improper buffer size calculations that subsequently result in heap corruption. The attack vector requires remote code execution through a malicious font file, often delivered via web browsing, email attachments, or malicious websites, allowing threat actors to gain unauthorized access to vulnerable systems. The technical nature of this vulnerability aligns with CWE-121, which describes heap-based buffer overflow conditions, and represents a classic example of how font processing components can serve as attack surfaces for privilege escalation and system compromise.
The operational impact of CVE-2009-0231 extends beyond simple code execution to encompass complete system compromise and potential lateral movement within network environments. When successfully exploited, the vulnerability allows attackers to execute malicious code with the privileges of the user account running the affected application, typically the SYSTEM account in Windows environments. This privilege escalation capability means that an attacker could gain full control over the compromised system, potentially leading to data exfiltration, persistence mechanisms, or further network reconnaissance. The vulnerability's remote exploitability makes it particularly dangerous for enterprise environments where users may unknowingly browse to malicious websites or open compromised email attachments containing malicious font files. The heap-based buffer overflow creates a condition where attacker-controlled data can overwrite adjacent memory locations, potentially corrupting critical program structures or injecting malicious code into the process memory space. This type of vulnerability is classified under the MITRE ATT&CK framework as part of the 'Exploitation for Privilege Escalation' technique, where adversaries leverage software vulnerabilities to gain elevated privileges and maintain persistent access to target systems.
Mitigation strategies for CVE-2009-0231 focus on both immediate patching and operational security measures to reduce exposure. Microsoft released security updates for all affected Windows versions, including Windows 2000, XP, Server 2003, Vista, and Server 2008, which address the integer truncation and buffer overflow conditions in the T2EMBED.DLL component. Organizations should prioritize immediate deployment of these patches to eliminate the vulnerability at its source. Beyond patching, network-based mitigations include implementing web content filtering solutions that can detect and block malicious font files, particularly those with unusual or suspicious characteristics in their name table structures. Security administrators should also consider disabling font rendering for untrusted content through browser security settings or application sandboxing techniques that prevent automatic font processing. Additional defensive measures involve monitoring for suspicious network traffic patterns that may indicate exploitation attempts, implementing host-based intrusion detection systems that can identify anomalous memory access patterns, and conducting regular vulnerability assessments to identify systems that may have been missed during patch deployment. Organizations should also consider implementing the principle of least privilege, ensuring that users have minimal necessary permissions to reduce the impact of successful exploitation attempts. The vulnerability's characteristics also make it a prime candidate for exploit prevention technologies such as data execution prevention, address space layout randomization, and heap spraying mitigation techniques that make successful exploitation more difficult for threat actors.