CVE-2007-4249 in ExportNation toolbar
Summary
by MITRE
The isChecked function in Toolbar.DLL in the ExportNation toolbar for Internet Explorer allows remote attackers to cause a denial of service (NULL dereference and browser crash) via unspecified vectors.
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Analysis
by VulDB Data Team • 10/25/2017
The vulnerability identified as CVE-2007-4249 represents a critical denial of service flaw within the ExportNation toolbar component for Internet Explorer. This issue resides in the Toolbar.DLL library and specifically targets the isChecked function implementation. The vulnerability manifests when remote attackers exploit unspecified vectors that lead to a NULL dereference condition within the browser's execution environment. Such a condition occurs when the software attempts to access memory at a null pointer location, causing the browser application to terminate unexpectedly and resulting in a complete crash of the user's browsing session.
The technical nature of this vulnerability aligns with CWE-476, which defines NULL pointer dereference as a common software weakness where an application attempts to access memory through a pointer that has not been properly initialized to a valid memory address. This particular flaw demonstrates how browser toolbars can introduce unstable code paths that directly impact the core browser functionality. When the isChecked function processes certain input parameters or executes under specific conditions, it fails to properly validate pointer references, leading to the exploitable state that allows attackers to trigger the NULL dereference condition.
From an operational impact perspective, this vulnerability creates significant risks for end users who may encounter unexpected browser crashes while browsing the internet. The denial of service condition effectively prevents users from continuing their browsing activities until the browser is manually restarted. Security researchers have identified that this vulnerability specifically affects Internet Explorer users who have the ExportNation toolbar installed, making it particularly dangerous in environments where multiple users may be running the same browser configuration. The unpredictable nature of the attack vectors means that users cannot easily avoid exploitation through simple browsing behavior modifications.
The attack surface for this vulnerability extends beyond simple user inconvenience to potentially enable more sophisticated exploitation techniques. While the immediate impact is a browser crash, the underlying NULL dereference condition could potentially be leveraged by attackers to execute arbitrary code or escalate privileges within the browser environment. This aligns with ATT&CK technique T1059 which describes how adversaries may use various methods to execute malicious code on compromised systems. Organizations should consider this vulnerability as part of a broader attack surface assessment, particularly when evaluating browser-based security controls and toolbar management policies.
Mitigation strategies for CVE-2007-4249 should focus on immediate removal of the ExportNation toolbar from affected systems, as this represents the most effective method to eliminate the threat. Security administrators should implement comprehensive browser policy controls that prevent installation of unauthorized toolbars and extensions. The vulnerability highlights the importance of maintaining updated browser configurations and implementing strict software whitelisting policies. Additionally, network administrators should consider deploying web filtering solutions that can block known malicious toolbar installations and monitor for suspicious browser behavior patterns that may indicate exploitation attempts. Regular security audits should include verification of installed browser extensions and toolbars to ensure compliance with organizational security standards and reduce the risk of similar vulnerabilities being exploited in the future.