CVE-2007-3661 in Virtual Serial Port
Summary
by MITRE
Eltima Software Virtual Serial Port (VSPAX) ActiveX control (VSPort.DLL) allows remote attackers to cause a denial of service via certain function calls, as demonstrated via the (1) Attach, (2) Write, and (3) WriteStr functions.
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Analysis
by VulDB Data Team • 10/28/2017
The vulnerability identified as CVE-2007-3661 affects the Eltima Software Virtual Serial Port (VSPAX) ActiveX control, specifically targeting the VSPort.DLL component that enables serial port emulation within Windows environments. This ActiveX control is commonly used in applications requiring serial communication simulation, particularly in industrial automation, embedded systems development, and legacy application compatibility scenarios where virtual serial ports are necessary for testing or operation. The flaw manifests in the control's handling of specific function calls that process serial port operations, creating a potential avenue for malicious exploitation that can severely impact system availability and operational continuity.
The technical implementation of this vulnerability stems from insufficient input validation and error handling within the Attach, Write, and WriteStr functions of the VSPort.DLL ActiveX control. When these functions receive malformed or specially crafted parameters, they fail to properly validate the input data, leading to memory corruption or resource exhaustion conditions that ultimately result in application crashes or system instability. This behavior aligns with CWE-121, which describes stack-based buffer overflow conditions, and CWE-122, which addresses heap-based buffer overflow vulnerabilities, though the specific manifestation occurs at the ActiveX control level rather than traditional code execution contexts. The vulnerability's remote exploitation capability means that attackers can trigger these conditions through network-based interactions without requiring local system access, making it particularly dangerous in enterprise environments where ActiveX controls are frequently deployed.
The operational impact of this vulnerability extends beyond simple denial of service conditions to encompass broader system stability and security implications. When exploited, the vulnerability can cause the affected ActiveX control to crash, leading to application termination and potential system instability, particularly in environments where serial port communication is critical for operational processes. In industrial control systems or embedded applications, this could result in production halts or operational failures that may have cascading effects throughout connected systems. The vulnerability's presence in widely deployed ActiveX controls also means that organizations may experience widespread impact across multiple applications and systems that utilize the VSPort.DLL component, potentially affecting everything from simple serial communication utilities to complex enterprise applications that depend on virtual serial port functionality.
Organizations should implement immediate mitigations including disabling ActiveX controls in web browsers where possible, implementing application whitelisting policies to restrict execution of vulnerable components, and applying vendor-specific patches or updates as available. The vulnerability demonstrates the importance of proper input validation and error handling in ActiveX controls, aligning with ATT&CK technique T1203 which covers legitimate user execution and T1059 which addresses command and scripting interpreters. System administrators should also consider network segmentation to limit exposure of systems that may execute vulnerable ActiveX controls, and implement monitoring solutions to detect anomalous function call patterns that could indicate exploitation attempts. The vulnerability serves as a reminder of the ongoing security challenges posed by legacy ActiveX components and the critical need for comprehensive vulnerability management programs that address both current and historical software components.