CVE-2007-3873 in PC-Cillin Internet Security 2007
Summary
by MITRE
Stack-based buffer overflow in vstlib32.dll 1.2.0.1012 in the SSAPI Engine 5.0.0.1066 through 5.2.0.1012 in Trend Micro AntiSpyware 3.5 and PC-Cillin Internet Security 2007 15.0 through 15.3, when the Venus Spy Trap (VST) feature is enabled, allows local users to cause a denial of service (service crash) or execute arbitrary code via a file with a long pathname, which triggers the overflow during a ReadDirectoryChangesW callback notification.
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Analysis
by VulDB Data Team • 10/31/2017
The vulnerability described in CVE-2007-3873 represents a critical stack-based buffer overflow affecting Trend Micro AntiSpyware 3.5 and PC-Cillin Internet Security 2007 versions within the SSAPI Engine component. This flaw exists in the vstlib32.dll library version 1.2.0.1012 and impacts all SSAPI Engine versions from 5.0.0.1066 through 5.2.0.1012. The vulnerability specifically manifests when the Venus Spy Trap (VST) feature is enabled, creating a dangerous condition that can be exploited by local attackers to either crash system services or execute arbitrary code with elevated privileges. The technical implementation involves the ReadDirectoryChangesW callback notification mechanism, which is a Windows API function used for monitoring directory changes and file system events. This callback functionality is fundamental to how the anti-spyware engine tracks and responds to potential threats in real-time monitoring scenarios.
The operational impact of this vulnerability extends beyond simple denial of service conditions to encompass full system compromise capabilities. When a malicious user places a file with an excessively long pathname in a monitored directory, the vulnerable code path within the vstlib32.dll library triggers a stack buffer overflow. This condition occurs because the software fails to properly validate or limit the length of pathname strings before processing them within the callback context. The buffer overflow creates an exploitable condition where attackers can overwrite critical stack memory locations, potentially allowing them to redirect program execution flow and inject malicious code. This vulnerability directly maps to CWE-121 Stack-based Buffer Overflow, which is classified as a critical weakness in the Common Weakness Enumeration catalog, specifically addressing buffer overflows that occur in stack memory regions.
The attack vector for this vulnerability is particularly concerning as it requires only local system access, making it accessible to users with basic system privileges rather than requiring elevated administrative rights. The exploitation process leverages the legitimate Windows file system monitoring capabilities that the anti-spyware software employs to detect suspicious activities, thereby bypassing typical security boundaries. According to ATT&CK framework categorization, this vulnerability aligns with T1059.007 Command and Scripting Interpreter: PowerShell and T1068 Exploitation for Privilege Escalation, as it enables local privilege escalation through code execution. The vulnerability also demonstrates characteristics of T1543.003 Create or Modify System Process: Windows Service, since the affected service crashes and potentially allows for further exploitation of the compromised system. The specific mechanism involves the ReadDirectoryChangesW API function which is commonly used for real-time file system monitoring and event detection in security applications, making this a particularly dangerous flaw in endpoint protection software.
Mitigation strategies for this vulnerability should include immediate patching of affected Trend Micro products to the latest available versions that contain the necessary code fixes for the buffer overflow condition. Organizations should disable the Venus Spy Trap feature if it is not actively required for their security operations, as this removes the attack surface that enables exploitation. System administrators should implement additional monitoring for unusual file system activity in monitored directories, particularly those that might trigger the problematic callback code path. The vulnerability highlights the importance of proper input validation and bounds checking in security software components, as the lack of adequate string length validation in the vstlib32.dll library creates an exploitable condition. Network segmentation and privilege separation measures should be implemented to limit the potential impact of successful exploitation, while regular security assessments should be conducted to identify similar buffer overflow conditions in other security applications. The vulnerability serves as a reminder that security software itself can contain exploitable flaws that attackers might leverage to compromise systems, emphasizing the need for comprehensive security testing and code review processes in all security-related components.