CVE-2011-4875 in SIMATIC HMI panel
Summary
by MITRE
Stack-based buffer overflow in HmiLoad in the runtime loader in Siemens WinCC flexible 2004, 2005, 2007, and 2008; WinCC V11 (aka TIA portal); the TP, OP, MP, Comfort Panels, and Mobile Panels SIMATIC HMI panels; WinCC V11 Runtime Advanced; and WinCC flexible Runtime, when Transfer Mode is enabled, allows remote attackers to execute arbitrary code via vectors related to Unicode strings.
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Analysis
by VulDB Data Team • 04/11/2025
The vulnerability identified as CVE-2011-4875 represents a critical stack-based buffer overflow affecting Siemens WinCC flexible and WinCC V11 products across multiple runtime environments. This flaw exists within the HmiLoad component of the runtime loader system, specifically when Transfer Mode is enabled during communication with HMI panels including TP, OP, MP, Comfort Panels, and Mobile Panels. The vulnerability stems from improper handling of Unicode strings during the loading process, creating a condition where attacker-controlled input can overwrite adjacent stack memory locations.
The technical implementation of this vulnerability involves the manipulation of Unicode string processing within the WinCC runtime environment. When Transfer Mode is active, the system processes incoming data streams containing Unicode encoded characters without adequate bounds checking mechanisms. The buffer overflow occurs because the application fails to validate the length of incoming Unicode strings before copying them into fixed-size stack buffers. This allows an attacker to craft malicious Unicode sequences that exceed the allocated buffer space, thereby corrupting adjacent memory regions including return addresses and control data. The vulnerability is classified as a stack-based buffer overflow under CWE-121, which specifically addresses buffer overflow conditions where data is written beyond the boundaries of stack buffers.
The operational impact of this vulnerability is severe as it enables remote code execution capabilities for attackers who can access the affected systems. Attackers can leverage this vulnerability to execute arbitrary code on the target systems without requiring local access or authentication. The attack surface includes all versions of Siemens WinCC flexible 2004 through 2008, WinCC V11 (TIA Portal), and various HMI panel types that utilize these runtime components. This vulnerability directly maps to ATT&CK technique T1203 (Exploitation for Client Execution) and T1059 (Command and Scripting Interpreter) within the enterprise attack framework, as it allows for remote code execution and system compromise.
Mitigation strategies for CVE-2011-4875 require immediate implementation of multiple defensive measures. Organizations should disable Transfer Mode functionality when it is not required for operational purposes, as this significantly reduces the attack surface. System administrators should implement network segmentation to isolate HMI systems from general corporate networks and apply strict firewall rules to limit access to affected runtime components. Additionally, Siemens released patches and updates for affected versions that address the buffer overflow condition through proper input validation and bounds checking mechanisms. Regular security assessments and vulnerability scanning should be conducted to identify any remaining instances of the vulnerable software. The remediation process should also include monitoring for suspicious network traffic patterns and implementing intrusion detection systems to identify potential exploitation attempts. Organizations must ensure all affected systems are updated to the latest secure versions and maintain comprehensive backup strategies to recover from potential compromise scenarios.