CVE-2011-4530 in Automation License Manager
Summary
by MITRE
Siemens Automation License Manager (ALM) 4.0 through 5.1+SP1+Upd1 does not properly copy fields obtained from clients, which allows remote attackers to cause a denial of service (exception and daemon crash) via long fields, as demonstrated by fields to the (1) open_session->workstation->NAME or (2) grant->VERSION function.
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Analysis
by VulDB Data Team • 04/06/2025
The Siemens Automation License Manager (ALM) vulnerability identified as CVE-2011-4530 represents a critical buffer overflow condition within the software's handling of client-provided data fields. This flaw exists in ALM versions 4.0 through 5.1+SP1+Upd1, affecting the industrial automation and control systems environment where proper input validation mechanisms are essential for system stability and security. The vulnerability stems from the improper copying of fields obtained from client connections, creating a scenario where maliciously crafted input can trigger unexpected behavior in the license management daemon.
The technical exploitation of this vulnerability occurs through the manipulation of specific data fields within the communication protocol used by the ALM system. Attackers can craft specially formatted input that exceeds the expected buffer sizes for the open_session->workstation->NAME or grant->VERSION function parameters. This improper field handling creates a condition where the software fails to properly validate input length before copying data into fixed-size buffers, leading to memory corruption. The vulnerability specifically targets the daemon process responsible for license management, making it particularly dangerous in industrial environments where continuous system availability is paramount.
The operational impact of this vulnerability extends beyond simple denial of service, as it can potentially disrupt critical industrial processes that depend on proper license management. When the daemon crashes due to the buffer overflow condition, it can lead to complete service interruption for the automation systems relying on licensed software components. This creates cascading effects in manufacturing environments where production lines depend on automated systems that require valid licensing. The vulnerability affects the availability aspect of the CIA triad, potentially causing significant operational disruptions that may require manual intervention to restore system functionality.
From a security perspective, this vulnerability aligns with CWE-121, which describes stack-based buffer overflow conditions, and represents a classic example of improper input validation in network services. The attack vector is remote, meaning that unauthorized users can exploit this vulnerability without physical access to the system. The flaw demonstrates the importance of implementing proper bounds checking and input validation in all network-facing services, particularly in industrial control systems where traditional security measures may not be sufficient. Organizations should consider implementing network segmentation and access controls to limit exposure to this type of vulnerability.
Mitigation strategies for CVE-2011-4530 should include immediate patching of affected ALM versions to the latest available updates from Siemens. System administrators should also implement network monitoring to detect unusual patterns of communication that might indicate exploitation attempts. Additional defensive measures include configuring firewalls to restrict access to ALM services only to trusted networks and implementing intrusion detection systems that can identify malformed packets targeting this specific vulnerability. The ATT&CK framework categorizes this type of vulnerability under privilege escalation and denial of service tactics, emphasizing the need for comprehensive security controls that address both availability and integrity concerns in industrial environments. Organizations should also conduct regular vulnerability assessments to identify similar issues in other industrial control system components and maintain updated incident response procedures for dealing with such critical vulnerabilities.