CVE-2011-4531 in Automation License Manager
Summary
by MITRE
Siemens Automation License Manager (ALM) 4.0 through 5.1+SP1+Upd1 allows remote attackers to cause a denial of service (NULL pointer dereference and daemon crash) via crafted content in a (1) get_target_ocx_param or (2) send_target_ocx_param command.
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Analysis
by VulDB Data Team • 04/06/2025
The Siemens Automation License Manager (ALM) vulnerability identified as CVE-2011-4531 represents a critical denial of service flaw affecting versions 4.0 through 5.1+SP1+Upd1 of the software. This vulnerability resides within the licensing management system used in industrial automation environments, specifically targeting the communication protocols that handle target ocx parameter requests. The flaw manifests when the ALM daemon processes malformed or crafted content in either the get_target_ocx_param or send_target_ocx_param commands, creating a condition that leads to a NULL pointer dereference. This type of vulnerability falls under CWE-476 which specifically addresses NULL pointer dereference conditions, making it a well-documented weakness in software security practices. The attack vector is particularly concerning as it operates over network communications, allowing remote exploitation without requiring physical access to the target system.
The technical implementation of this vulnerability demonstrates how industrial control systems often lack proper input validation mechanisms in their communication protocols. When the ALM daemon receives maliciously crafted data in the specified command parameters, the software fails to properly validate the incoming content before attempting to dereference pointers that may be null or improperly initialized. This results in an immediate crash of the daemon process, effectively rendering the license management service unavailable. The operational impact extends beyond simple service disruption as the ALM daemon is integral to the licensing and authorization functions of Siemens automation systems, potentially affecting the entire operational technology infrastructure that relies on proper license validation. The vulnerability's classification as a remote attack means that threat actors can exploit this weakness from external networks, making it particularly dangerous in industrial environments where network segmentation may be insufficient.
From an operational security perspective, this vulnerability represents a significant risk to industrial control systems and their associated cybersecurity posture. The denial of service condition caused by the NULL pointer dereference directly impacts the availability of critical licensing services that may be required for system operation and maintenance. The attack surface is broad as the vulnerability affects multiple versions of the ALM software, indicating that organizations running various generations of Siemens automation products may be at risk. According to ATT&CK framework, this vulnerability aligns with the T1499.004 technique related to network denial of service attacks, and could potentially be leveraged as part of a broader attack chain targeting industrial control systems. The lack of authentication requirements for the vulnerable commands further compounds the risk, as the attack can be executed without prior credentials or access to the system.
Organizations affected by this vulnerability should implement immediate mitigations including network segmentation to isolate the ALM service from general network access, deployment of network monitoring tools to detect anomalous traffic patterns, and application of vendor patches when available. The recommended approach involves configuring firewalls to restrict access to the ALM communication ports and implementing intrusion detection systems that can identify malformed parameter requests. Additionally, regular security assessments of industrial control systems should include evaluation of communication protocols for similar input validation weaknesses. The vulnerability also highlights the importance of maintaining current security patches for industrial software components, as the ALM service represents a critical infrastructure element that requires robust protection against both external and internal threats. System administrators should also consider implementing automated monitoring solutions that can detect daemon crashes and alert security teams to potential exploitation attempts.