CVE-2016-9154 in Desigo PX Web Module
Summary
by MITRE
Siemens Desigo PX Web modules PXA40-W0, PXA40-W1, PXA40-W2 for Desigo PX automation controllers PXC00-E.D, PXC50-E.D, PXC100-E.D, PXC200-E.D (All firmware versions < V6.00.046) and Desigo PX Web modules PXA30-W0, PXA30-W1, PXA30-W2 for Desigo PX automation controllers PXC00-U, PXC64-U, PXC128-U (All firmware versions < V6.00.046) use a pseudo random number generator with insufficient entropy to generate certificates for HTTPS, potentially allowing remote attackers to reconstruct the corresponding private key.
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Analysis
by VulDB Data Team • 10/12/2022
The vulnerability identified as CVE-2016-9154 affects Siemens Desigo PX automation controllers and their associated web modules, specifically impacting hardware models PXA40-W0, PXA40-W1, PXA40-W2 and PXA30-W0, PXA30-W1, PXA30-W2. These modules operate within industrial automation environments where security is paramount for operational technology systems. The affected controllers include PXC00-E.D, PXC50-E.D, PXC100-E.D, PXC200-E.D and PXC00-U, PXC64-U, PXC128-U models, all running firmware versions prior to V6.00.046. This vulnerability resides in the cryptographic implementation used for generating secure HTTPS certificates, representing a fundamental weakness in the system's security infrastructure that directly impacts the confidentiality and integrity of communications between operators and automation systems.
The core technical flaw involves the implementation of a pseudo random number generator that demonstrates insufficient entropy during certificate generation processes. This weakness stems from the predictable nature of the random number sequence generated by the system, which allows attackers to potentially reconstruct the private keys associated with the HTTPS certificates. The vulnerability maps directly to CWE-330, which addresses the use of insufficiently random values, and specifically relates to the improper generation of cryptographic keys through weak random number generation. The low entropy values used in the pseudo random number generator compromise the security guarantees typically provided by asymmetric cryptography, making the system vulnerable to cryptographic attacks that would normally be computationally infeasible.
The operational impact of this vulnerability extends beyond simple network security concerns into critical industrial control system risks. Remote attackers who can successfully reconstruct private keys gain the ability to impersonate legitimate automation systems, potentially leading to unauthorized access to critical infrastructure operations. This vulnerability creates opportunities for man-in-the-middle attacks where attackers can intercept and modify communications between operators and the automation controllers. The implications are particularly severe in industrial environments where these controllers manage physical processes, as compromised systems could lead to operational disruptions, safety hazards, or even physical damage to equipment. The vulnerability affects the integrity of the secure communication channels that are essential for maintaining the operational security posture of industrial automation systems.
Mitigation strategies for CVE-2016-9154 primarily focus on firmware upgrades to versions V6.00.046 or later, which contain fixed implementations of cryptographic random number generation. Organizations should also implement network segmentation to limit access to these automation systems and deploy additional monitoring controls to detect unauthorized access attempts. Security professionals should consider implementing certificate pinning mechanisms and regular cryptographic audits of industrial control systems. The vulnerability demonstrates the importance of proper entropy sources in cryptographic implementations and aligns with ATT&CK technique T1552.001 for unsecured credentials and T1071.004 for application layer protocol traffic. Organizations should also conduct comprehensive risk assessments of their industrial control systems to identify similar vulnerabilities in other cryptographic implementations and ensure that all security updates are properly deployed across their operational technology infrastructure.