CVE-2014-2251 in SIMATIC S7-1500 Cpu
Summary
by MITRE
The random-number generator on Siemens SIMATIC S7-1500 CPU PLC devices with firmware before 1.5.0 does not have sufficient entropy, which makes it easier for remote attackers to defeat cryptographic protection mechanisms and hijack sessions via unspecified vectors.
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Analysis
by VulDB Data Team • 05/08/2026
The vulnerability identified as CVE-2014-2251 affects Siemens SIMATIC S7-1500 CPU programmable logic controllers where the random number generator lacks adequate entropy levels in firmware versions prior to 1.5.0. This weakness resides in the fundamental cryptographic infrastructure of these industrial control systems, creating a significant security risk for critical infrastructure environments. The insufficient entropy in the random number generation process compromises the unpredictability essential for cryptographic security mechanisms, making these devices particularly susceptible to attacks targeting session hijacking and cryptographic protection bypass.
The technical flaw manifests in the inadequate entropy sources used by the random number generator within the PLC firmware, which directly violates established cryptographic standards and best practices. According to CWE-330, this represents a weakness in entropy sources where insufficient randomness compromises cryptographic security. The vulnerability enables remote attackers to predict or reproduce the random sequences used for cryptographic operations, session identifiers, and security tokens. This weakness operates at the core of the device's security architecture, potentially allowing attackers to forge authentication tokens, decrypt communications, or predict session identifiers that would normally be protected by strong cryptographic randomness.
The operational impact of this vulnerability extends beyond simple cryptographic weakness to represent a critical threat to industrial control system security. Attackers exploiting this vulnerability could potentially gain unauthorized access to industrial processes, manipulate control operations, or disrupt critical infrastructure functions. The unspecified vectors mentioned in the description suggest multiple attack surfaces including network-based exploitation, which aligns with ATT&CK technique T1547.001 for hijacking sessions and T1566 for credential manipulation. These PLCs are commonly deployed in manufacturing environments, power generation facilities, and other critical infrastructure sectors where such compromises could result in significant operational disruption or safety hazards.
Mitigation strategies for CVE-2014-2251 primarily focus on firmware updates to version 1.5.0 or later, which address the entropy deficiency in the random number generator implementation. Organizations should conduct comprehensive inventory assessments to identify all affected SIMATIC S7-1500 devices and prioritize their remediation based on risk assessment. Network segmentation and access control measures should be implemented to limit exposure of these devices to untrusted networks. Additionally, security monitoring should be enhanced to detect anomalous behavior that might indicate exploitation attempts, particularly around authentication and session management activities. The vulnerability highlights the importance of cryptographic security in industrial environments and underscores the need for proper entropy sources in embedded systems, as mandated by various industrial security standards and frameworks including NIST SP 800-90A for random number generation requirements.