CVE-2009-2494 in Windows
Summary
by MITRE
The Active Template Library (ATL) 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 vectors related to erroneous free operations after reading a variant from a stream and deleting this variant, aka "ATL Object Type Mismatch Vulnerability."
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Analysis
by VulDB Data Team • 06/01/2025
The CVE-2009-2494 vulnerability represents a critical memory corruption flaw within Microsoft's Active Template Library implementation across multiple Windows operating systems. This vulnerability stems from improper handling of object types during stream processing operations, specifically when variants are read from streams and subsequently freed. The flaw manifests as an object type mismatch condition that occurs during the ATL's internal memory management routines, creating a predictable pattern of memory corruption that attackers can exploit to gain arbitrary code execution privileges.
The technical exploitation of this vulnerability occurs through a specific sequence involving stream-based data processing where the ATL library fails to properly validate object types before performing memory deallocation operations. When a malicious variant is read from an external stream and subsequently deleted, the library's memory management code attempts to free memory using incorrect object type information, leading to heap corruption. This memory corruption enables attackers to overwrite critical memory locations and ultimately execute malicious code with the privileges of the targeted process. The vulnerability is particularly dangerous because it can be triggered through various attack vectors including web-based content, email attachments, and file processing operations that utilize ATL components.
From an operational perspective, this vulnerability presents significant risk to enterprise environments as it affects multiple versions of Windows that were widely deployed in corporate networks. The attack surface includes web browsers, email clients, and any application that leverages ATL for processing external data streams. The vulnerability's remote exploitability means that attackers can potentially compromise systems without requiring local access, making it particularly dangerous in unpatched environments. Security researchers have classified this as a high-severity vulnerability due to its reliable exploitability and the potential for privilege escalation, with the ATT&CK framework categorizing this under the T1059.007 technique for command and scripting interpreter execution.
The vulnerability aligns with CWE-122, which describes "Heap-based Buffer Overflow" conditions, and demonstrates how improper memory management in library components can lead to remote code execution. Organizations affected by this vulnerability should prioritize immediate patch deployment through Microsoft's security updates, as the flaw remains exploitable in unpatched systems. Mitigation strategies include implementing application whitelisting policies, disabling unnecessary ATL-based functionality, and monitoring for suspicious memory allocation patterns in affected applications. The vulnerability also highlights the importance of proper input validation and memory management practices in library code, with security best practices recommending regular security assessments of third-party components and adherence to secure coding guidelines that prevent similar heap corruption scenarios.
This vulnerability serves as a critical reminder of the importance of proper memory management in system libraries and demonstrates how flaws in core components can affect wide ranges of applications and operating systems. The exploitation techniques required for this vulnerability are well-documented in cybersecurity research and have been widely studied by both researchers and malicious actors, emphasizing the need for comprehensive security patch management and proactive vulnerability remediation strategies across enterprise environments.