CVE-2016-7959 in SIMATIC Step 7
Summary
by MITRE
Siemens SIMATIC STEP 7 (TIA Portal) before 14 improperly stores pre-shared key data in TIA project files, which makes it easier for local users to obtain sensitive information by leveraging access to a file and conducting a brute-force attack.
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Analysis
by VulDB Data Team • 09/26/2022
The vulnerability identified as CVE-2016-7959 affects Siemens SIMATIC STEP 7 (TIA Portal) versions prior to 14, representing a critical information disclosure weakness that compromises the security of industrial automation environments. This flaw resides in how the software handles pre-shared key data storage within TIA project files, creating an exploitable condition that undermines the confidentiality of sensitive cryptographic information. The vulnerability specifically impacts the TIA Portal environment used for programming and configuring industrial control systems, making it particularly concerning for operational technology infrastructure. The improper storage mechanism allows local users with access to project files to extract pre-shared keys that should remain protected, thereby weakening the overall security posture of industrial automation systems.
The technical implementation of this vulnerability stems from the insecure handling of cryptographic material within project file structures. When TIA Portal saves project files, it inadvertently persists pre-shared key information in a manner that does not adequately protect sensitive data elements. This misconfiguration allows attackers with local file access to examine project files and extract cryptographic keys that are essential for secure communications between industrial devices and control systems. The flaw essentially creates a data exposure scenario where the confidentiality of pre-shared keys is compromised through routine file access patterns. According to CWE-312, this represents a weakness where sensitive data is stored in cleartext or improperly encrypted within application files, making it vulnerable to unauthorized access. The vulnerability's impact is amplified because it requires minimal privileges for exploitation, as local access to project files is sufficient to conduct brute-force attacks against the extracted key material.
The operational implications of CVE-2016-7959 extend beyond simple information disclosure, as it fundamentally undermines the security of industrial control systems that rely on authenticated communications. Local users who can access project files can leverage this vulnerability to perform credential stuffing or brute-force attacks against networked industrial devices, potentially gaining unauthorized access to critical infrastructure components. This vulnerability directly impacts the integrity and availability of industrial automation systems, as compromised keys may enable attackers to impersonate legitimate devices or disrupt communication channels. The attack surface is particularly concerning in environments where multiple users have local access to project files, as it creates a persistent threat vector that remains active as long as project files are stored on accessible systems. From an ATT&CK framework perspective, this vulnerability maps to T1566 (Phishing for Information) and T1078 (Valid Accounts) as attackers can exploit the exposed keys to establish persistent access to industrial control systems.
Mitigation strategies for CVE-2016-7959 focus on both immediate remediation and long-term security hardening measures. The primary recommendation involves upgrading to Siemens TIA Portal version 14 or later, which addresses the improper key storage mechanism through enhanced encryption and access controls. Organizations should implement strict file access controls and privilege management to limit local user access to project files containing sensitive cryptographic information. Regular security assessments of industrial automation environments should include checks for the presence of vulnerable TIA Portal versions and proper key management practices. Network segmentation and monitoring solutions should be deployed to detect unauthorized access attempts to industrial control system files. Additionally, organizations should establish secure key management practices that separate key storage from project files and implement automated systems to regularly rotate cryptographic materials. The vulnerability highlights the importance of secure development practices in industrial software, particularly regarding the handling of sensitive data elements that should never be stored in accessible file formats without proper encryption. Organizations should also consider implementing security awareness training for industrial control system operators to prevent accidental exposure of sensitive project files through insecure file sharing or storage practices.