CVE-2011-4879 in SIMATIC HMI panel
Summary
by MITRE
miniweb.exe in the HMI web server in Siemens WinCC flexible 2004, 2005, 2007, and 2008 before SP3; WinCC V11 (aka TIA portal) before SP2 Update 1; the TP, OP, MP, Comfort Panels, and Mobile Panels SIMATIC HMI panels; WinCC V11 Runtime Advanced; and WinCC flexible Runtime does not properly handle URIs beginning with a 0xfa character, which allows remote attackers to read data from arbitrary memory locations or cause a denial of service (application crash) via a crafted POST request.
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Analysis
by VulDB Data Team • 04/07/2025
The vulnerability identified as CVE-2011-4879 represents a critical memory corruption flaw within the HMI web server component of Siemens WinCC products, specifically affecting miniweb.exe executable. This issue stems from inadequate input validation mechanisms when processing Uniform Resource Identifiers that begin with the 0xfa character sequence, creating a pathway for remote attackers to exploit memory access patterns. The affected systems span multiple versions of Siemens WinCC flexible including 2004, 2005, 2007, and 2008, as well as WinCC V11 and related HMI panels such as TP, OP, MP, Comfort Panels, and Mobile Panels. The vulnerability manifests through crafted POST requests that manipulate URI parsing, allowing attackers to traverse memory boundaries beyond intended application limits.
The technical exploitation of this vulnerability operates through a buffer over-read condition that occurs when the miniweb.exe process encounters URIs starting with the 0xfa character. This specific byte sequence triggers improper memory handling within the web server's URI processing logic, which fails to validate or sanitize input before proceeding with memory access operations. The flaw enables attackers to craft malicious requests that cause the web server to read arbitrary memory locations, potentially exposing sensitive data or system information. The vulnerability also presents a denial of service vector where carefully constructed requests can cause application crashes and system instability, effectively rendering the HMI web server unavailable to legitimate users. This memory handling deficiency aligns with CWE-125, which describes out-of-bounds read vulnerabilities, and CWE-129, addressing improper validation of array indices.
The operational impact of this vulnerability extends beyond simple data exposure, as it compromises the integrity and availability of critical industrial control systems. In industrial environments where Siemens WinCC HMI systems control manufacturing processes, energy distribution, or other critical infrastructure, this vulnerability could enable attackers to gain unauthorized access to operational data or disrupt system availability. The remote nature of the attack means that adversaries do not require physical access to the systems, making the vulnerability particularly dangerous in connected industrial environments. The affected HMI panels represent critical user interfaces for industrial processes, and compromising their web servers could provide attackers with pathways to deeper system compromises or direct control over industrial operations. According to ATT&CK framework, this vulnerability maps to T1190 - Exploit Public-Facing Application and T1499 - Endpoint Termination, as it enables both remote exploitation and potential system disruption.
Mitigation strategies for CVE-2011-4879 should prioritize immediate patching of affected systems with the relevant Siemens security updates, particularly SP3 for WinCC flexible versions and SP2 Update 1 for WinCC V11. Network segmentation and access controls should be implemented to restrict unauthorized access to HMI web servers, while monitoring systems should be deployed to detect anomalous URI patterns or POST requests that might indicate exploitation attempts. Organizations should also consider implementing intrusion detection systems specifically configured to identify patterns associated with this vulnerability. The vulnerability highlights the importance of input validation in industrial web server implementations and demonstrates how seemingly minor character handling issues can result in significant security risks. Regular security assessments of industrial control systems should include evaluation of web server components and their input validation mechanisms to prevent similar vulnerabilities from being present in operational environments.