CVE-2009-2519 in Windows
Summary
by MITRE
The DHTML Editing Component ActiveX control in Microsoft Windows 2000 SP4, XP SP2 and SP3, and Server 2003 SP2 does not properly format HTML markup, which allows remote attackers to execute arbitrary code via a crafted web site that triggers "system state" corruption, aka "DHTML Editing Component ActiveX Control Vulnerability."
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Analysis
by VulDB Data Team • 03/30/2025
The CVE-2009-2519 vulnerability represents a critical buffer overflow flaw within the DHTML Editing Component ActiveX control that affected multiple Microsoft Windows operating systems including Windows 2000 SP4, XP SP2 and SP3, and Server 2003 SP2. This vulnerability stems from improper HTML markup handling within the ActiveX control, creating a condition where maliciously crafted web content can trigger system state corruption. The flaw specifically manifests when the control processes malformed HTML content, leading to memory corruption that adversaries can exploit to execute arbitrary code with the privileges of the user running the vulnerable component. This vulnerability is particularly concerning because it operates through web-based attack vectors, making it accessible to remote threat actors without requiring local system access. The DHTML Editing Component ActiveX control is commonly integrated into web browsers and applications that support rich text editing functionality, providing an attack surface that extends beyond traditional browser exploitation methods.
The technical root cause of this vulnerability aligns with CWE-121, which describes stack-based buffer overflow conditions, and more specifically with CWE-125, representing out-of-bounds read vulnerabilities. The flaw occurs during HTML parsing within the ActiveX control's memory management system, where insufficient bounds checking allows attackers to overwrite adjacent memory locations. When a user visits a malicious website containing crafted HTML content, the DHTML Editing Component processes this content without adequate validation, leading to memory corruption that can be leveraged to overwrite critical system structures. The vulnerability's exploitation requires the user to interact with a malicious webpage, making it a classic example of a remote code execution vulnerability that operates through web browsers and ActiveX-enabled applications. This type of vulnerability typically falls under the ATT&CK framework's technique T1203, which covers Exploitation for Client Execution, where adversaries leverage vulnerabilities in client applications to execute malicious code.
The operational impact of CVE-2009-2519 extends beyond simple code execution, as successful exploitation can lead to complete system compromise and privilege escalation. Attackers can leverage this vulnerability to install malware, steal sensitive information, or establish persistent backdoors within affected systems. The widespread deployment of Windows operating systems made this vulnerability particularly dangerous, as it affected numerous enterprise environments where ActiveX controls were commonly used for web-based applications and content management systems. Organizations running affected versions of Windows were at significant risk since the vulnerability could be triggered through standard web browsing activities without requiring any special user interaction beyond visiting a malicious website. The vulnerability's exploitation often results in system instability and potential denial of service conditions, making it a preferred target for both malicious actors seeking to gain unauthorized access and for legitimate security researchers identifying system weaknesses. The attack vector typically involves hosting malicious content on compromised websites or through phishing campaigns that direct users to exploit the vulnerable ActiveX control through their web browsers.
Mitigation strategies for CVE-2009-2519 primarily focus on patch management and security configuration controls. Microsoft released security updates addressing this vulnerability through Windows Update and Microsoft Security Bulletin MS09-037, which provided patches to fix the buffer overflow conditions in the DHTML Editing Component. Organizations should prioritize immediate deployment of these security updates across all affected systems to prevent exploitation. Additional defensive measures include disabling ActiveX controls in web browsers, implementing proper web content filtering, and configuring security settings to restrict ActiveX control execution. Network administrators should consider implementing intrusion detection systems to monitor for exploitation attempts targeting this vulnerability, as well as conducting regular vulnerability assessments to identify unpatched systems. The vulnerability also highlights the importance of application whitelisting and the principle of least privilege, where ActiveX controls should only be enabled for trusted applications and users. Security teams should also implement web application firewalls and content filtering solutions to block access to known malicious websites that may host exploit code for this vulnerability. Regular security awareness training for users can help prevent successful exploitation through social engineering attacks that leverage this vulnerability. The remediation process should include comprehensive testing of patches in controlled environments before widespread deployment to ensure compatibility with existing applications and business processes.