CVE-2011-4514 in SIMATIC HMI panel
Summary
by MITRE
The TELNET daemon 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 does not perform authentication, which makes it easier for remote attackers to obtain access via a TCP session.
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Analysis
by VulDB Data Team • 11/29/2021
The vulnerability identified as CVE-2011-4514 represents a critical authentication flaw in the telnet daemon implementation across multiple Siemens WinCC products and HMI panels. This weakness exists in versions ranging from WinCC flexible 2004 through 2008, WinCC V11 (TIA Portal), and various SIMATIC HMI panels including TP, OP, MP, Comfort Panels, and Mobile Panels. The fundamental issue lies in the complete absence of authentication mechanisms within the telnet service, creating an inherent security gap that allows unauthorized remote access to industrial control systems. This vulnerability directly impacts the security posture of industrial environments where these systems are deployed, as it eliminates the primary barrier that should prevent unauthorized users from establishing connections to critical operational infrastructure.
The technical flaw manifests as a missing authentication requirement in the telnet daemon implementation, which operates on standard TCP ports typically used for remote administrative access. When a remote attacker establishes a TCP session with the affected system, no credential verification occurs, allowing immediate access to the system's command interface. This design flaw violates fundamental security principles and creates an attack surface that aligns with CWE-287, which addresses improper authentication vulnerabilities. The absence of authentication mechanisms means that any network traffic reaching the telnet port can potentially gain system access, making the vulnerability particularly dangerous in industrial environments where operational technology (OT) systems require robust security controls.
The operational impact of this vulnerability extends beyond simple unauthorized access, as it fundamentally compromises the integrity and availability of industrial control systems. Attackers can exploit this weakness to gain full administrative control over the affected systems, potentially leading to system manipulation, data compromise, or operational disruption. In industrial environments, this vulnerability could enable attackers to modify critical process parameters, disable safety mechanisms, or cause production disruptions that could result in significant financial losses or safety hazards. The vulnerability's widespread presence across multiple Siemens products and HMI panels amplifies its impact, as it affects various stages of industrial automation and control processes. This weakness directly maps to attack techniques described in the MITRE ATT&CK framework under initial access and privilege escalation tactics, where attackers can leverage unauthenticated access to establish persistent control over critical infrastructure.
Mitigation strategies for CVE-2011-4514 should prioritize the immediate disablement or removal of the telnet service on affected systems, as this represents the most effective immediate solution. Organizations should implement network segmentation to isolate critical industrial systems from general network access, thereby reducing the attack surface available to potential remote attackers. The deployment of network access control lists and firewall rules to block telnet traffic on standard ports 23 and 2323 can provide additional protective layers. System administrators should also consider implementing secure remote access solutions such as SSH instead of telnet, as well as establishing robust network monitoring to detect unauthorized telnet connection attempts. Regular vulnerability assessments and security audits should be conducted to identify and remediate similar authentication weaknesses across industrial control systems. Given the age of affected products and the long-term nature of industrial infrastructure, organizations should also consider system upgrades or replacements to ensure continued security against evolving threats, particularly as the industrial cybersecurity landscape continues to mature with standards like NIST SP 800-82 and IEC 62443 providing guidance for secure industrial automation and control systems.