CVE-2024-49849 is a deserialization of untrusted data vulnerability (CWE-502) identified in a broad range of Siemens industrial automation software products, including SIMATIC S7-PLCSIM V16 and V17, STEP 7 Safety versions up to V19 Update 4, WinCC Unified versions up to V19 Update 4, SIMOCODE ES, SIMOTION SCOUT TIA, SINAMICS Startdrive, SIRIUS Safety ES, SIRIUS Soft Starter ES, and TIA Portal Cloud versions up to V19 (with some update exceptions). The root cause is the improper sanitization of user-controllable input during the parsing of log files, which allows an attacker to induce type confusion. This type confusion can lead to arbitrary code execution within the context of the affected application. The vulnerability requires local access (attack vector: local), no privileges (PR:N), but does require user interaction (UI:R), such as opening or processing a maliciously crafted log file. The scope is unchanged (S:U), but the impact on confidentiality, integrity, and availability is high (C:H/I:H/A:H), meaning an attacker can fully compromise the affected system. The CVSS v3.1 base score is 7.8, indicating a high-severity issue. Although no known exploits are currently reported in the wild, the vulnerability poses a significant risk due to the critical nature of the affected Siemens software, which is widely used in industrial control systems (ICS) and manufacturing environments. The vulnerability was published on December 10, 2024, with Siemens as the assigner. The affected products are integral to industrial automation, safety systems, and process control, making the potential impact severe if exploited.

For European organizations, particularly those in manufacturing, utilities, energy, and critical infrastructure sectors, this vulnerability presents a serious risk. Siemens automation software is extensively deployed across Europe, especially in countries with advanced industrial bases such as Germany, France, Italy, and the UK. Successful exploitation could allow attackers to execute arbitrary code, potentially leading to disruption of industrial processes, safety system failures, data breaches, and operational downtime. This could result in financial losses, safety hazards, regulatory non-compliance, and reputational damage. Given the high confidentiality, integrity, and availability impact, attackers could manipulate control logic, alter safety parameters, or disable monitoring systems. The requirement for local access and user interaction somewhat limits remote exploitation but does not eliminate risk, especially in environments where insider threats or phishing attacks could deliver malicious log files. The absence of known exploits in the wild provides a window for proactive mitigation, but the criticality of affected systems demands urgent attention.

1. Apply Siemens security updates and patches as soon as they become available for all affected products and versions. 2. Restrict access to log files and directories to authorized personnel only, implementing strict file permissions and access controls. 3. Implement application whitelisting and endpoint protection to detect and block unauthorized code execution. 4. Educate users and operators about the risks of opening or processing untrusted log files and enforce policies to verify file integrity before use. 5. Monitor systems for unusual behavior or indicators of compromise, including unexpected process executions or modifications to log files. 6. Isolate critical industrial control systems from general IT networks to reduce the risk of local exploitation. 7. Employ network segmentation and strict access controls to limit lateral movement if an attacker gains local access. 8. Conduct regular security audits and vulnerability assessments focused on industrial automation environments. 9. Use logging and alerting mechanisms to detect attempts to exploit deserialization vulnerabilities. 10. Collaborate with Siemens support and cybersecurity teams to stay informed about updates and best practices.