CVE-2002-0070 in Windows
Summary
by MITRE
Buffer overflow in Windows Shell (used as the Windows Desktop) allows local and possibly remote attackers to execute arbitrary code via a custom URL handler that has not been removed for an application that has been improperly uninstalled.
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Analysis
by VulDB Data Team • 07/27/2019
The vulnerability identified as CVE-2002-0070 represents a critical buffer overflow flaw within the Windows Shell component that serves as the foundational desktop environment for Microsoft Windows operating systems. This weakness resides in how the shell handles custom URL handlers, specifically when applications that have been improperly uninstalled fail to completely remove their associated handler registrations from the system registry. The buffer overflow occurs when the shell processes these malformed URL handler entries, leading to potential code execution privileges for malicious actors. The vulnerability is particularly concerning because it can be exploited both locally and remotely, expanding the attack surface significantly beyond traditional local privilege escalation scenarios. The Windows Shell component, which manages the desktop environment, file associations, and application launching mechanisms, becomes a prime target for exploitation due to its central role in system operations and its extensive interaction with user input through URL handling mechanisms.
The technical implementation of this vulnerability stems from inadequate input validation within the Windows Shell's URL handler processing logic. When an application is improperly uninstalled, remnants of its URL handler registration remain in the Windows registry, creating a persistent entry point that the shell continues to process. During normal operation, when a user interacts with a URL that references one of these leftover handlers, the shell attempts to parse and execute the handler without proper bounds checking. The buffer overflow occurs when the parsed handler data exceeds the allocated memory buffer size, causing adjacent memory to be overwritten. This memory corruption can be manipulated to redirect program execution flow, allowing attackers to inject and execute arbitrary code with the privileges of the user running the shell. The vulnerability is classified under CWE-121 as a stack-based buffer overflow, which aligns with the Windows Shell's handling of user-supplied data through URL protocols. The attack vector is particularly insidious because it leverages legitimate system functionality while exploiting the remnants of previous installations, making detection more challenging for security monitoring systems.
The operational impact of CVE-2002-0070 extends far beyond simple privilege escalation, as it provides attackers with comprehensive system compromise capabilities through multiple attack paths. Local exploitation can occur when a user visits a malicious website or opens a specially crafted file that triggers the vulnerable URL handler, while remote exploitation becomes possible through network-based attacks that leverage the same vulnerability. The attacker can execute code with the privileges of the logged-in user, potentially leading to full system compromise depending on the user's access level. This vulnerability directly maps to several techniques described in the ATT&CK framework, particularly those related to privilege escalation and execution through legitimate system processes. The attack can be amplified through social engineering tactics where users are tricked into visiting malicious websites or opening compromised documents, making this vulnerability particularly dangerous in enterprise environments where users may encounter untrusted content. The persistence aspect of this vulnerability means that once exploited, attackers can maintain access through the continued presence of the malformed registry entries, even after system reboots or normal application reinstallations.
Mitigation strategies for CVE-2002-0070 require comprehensive system hardening approaches that address both immediate remediation and long-term prevention. The most effective immediate solution involves proper application uninstallation procedures that ensure complete removal of registry entries and handler registrations, which can be achieved through registry cleanup utilities or manual verification of registry keys under HKEY_CLASSES_ROOT. System administrators should implement regular registry auditing to identify and remove orphaned URL handler entries that may indicate improperly uninstalled applications. The Windows operating system itself should be updated with the latest security patches from Microsoft, which address the underlying buffer overflow conditions in the shell component. Network-level protections such as URL filtering and application whitelisting can help prevent exploitation by blocking access to malicious URLs that trigger the vulnerable handlers. Additionally, implementing least privilege principles and user account control measures can limit the impact of successful exploitation attempts, while regular security monitoring should focus on detecting unusual registry modifications or suspicious URL handler activity. Organizations should also consider implementing security awareness training to reduce the risk of social engineering attacks that leverage this vulnerability, as the human factor remains a critical component in successful exploitation of such desktop-level vulnerabilities.