CVE-2021-40360 in SIMATIC PCS 7
Summary
by MITRE • 02/09/2022
A vulnerability has been identified in SIMATIC PCS 7 V8.2 and earlier (All versions), SIMATIC PCS 7 V9.0 (All versions), SIMATIC PCS 7 V9.1 (All versions < V9.1 SP1), SIMATIC WinCC V15 and earlier (All versions), SIMATIC WinCC V16 (All versions < V16 Update 5), SIMATIC WinCC V17 (All versions < V17 Update 2), SIMATIC WinCC V7.4 and earlier (All versions), SIMATIC WinCC V7.5 (All versions < V7.5 SP2 Update 6). The password hash of a local user account in the remote server could be granted via public API to a user on the affected system. An authenticated attacker could brute force the password hash and use it to login to the server.
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Analysis
by VulDB Data Team • 02/12/2022
This vulnerability exists within Siemens industrial automation software products including SIMATIC PCS 7 and SIMATIC WinCC across multiple versions, representing a critical authentication weakness that could enable unauthorized system access. The flaw manifests through a public application programming interface that inadvertently exposes password hash information for local user accounts on affected servers. This represents a significant deviation from secure authentication practices where password hashes should remain protected within secure server-side storage mechanisms rather than being accessible through exposed endpoints.
The technical implementation of this vulnerability stems from inadequate access controls and authentication boundary enforcement within the software's API design. When authenticated users interact with the affected systems, the public API endpoints fail to properly validate access permissions for password hash retrieval operations. This allows any user with basic authentication credentials to potentially access password hash information that should remain restricted to authorized administrative functions. The vulnerability aligns with CWE-284 (Improper Access Control) and CWE-306 (Missing Authentication for Critical Function) classifications, indicating weak authorization mechanisms and insufficient protection of sensitive authentication data.
The operational impact of this vulnerability is severe for industrial control systems and process automation environments where these Siemens products are deployed. An authenticated attacker who gains access to the system can leverage the exposed password hashes to perform offline brute force attacks against the password complexity. This creates a significant risk of unauthorized system compromise where attackers can escalate privileges and gain full administrative control over the affected automation systems. The vulnerability particularly affects critical infrastructure environments where system integrity and security are paramount, potentially enabling attackers to disrupt industrial processes or gain access to sensitive operational data.
Organizations should implement immediate mitigations including applying the latest vendor patches and updates to address the authentication exposure. Network segmentation should be enforced to limit access to these systems, with strict firewall rules preventing unauthorized API access. Administrative access to these systems should be restricted to minimal necessary personnel with strong authentication mechanisms. The implementation of multi-factor authentication and regular security audits of system access controls should be mandatory. According to ATT&CK framework, this vulnerability maps to T1110 (Brute Force) and T1078 (Valid Accounts) techniques, highlighting the importance of account protection and access control monitoring. Regular penetration testing and vulnerability assessments should be conducted to identify similar exposure points in industrial control system environments, as these systems often lack the robust security controls found in traditional IT environments.