CVE-2022-42891 is a high-severity vulnerability affecting Siemens syngo Dynamics, a medical imaging software platform widely used in healthcare environments for diagnostic imaging workflows. The vulnerability is classified under CWE-73: External Control of File Name or Path. It arises from improper write access control in a web service operation hosted by the syngo Dynamics application server. Specifically, the vulnerable operation allows an attacker to write arbitrary data to any folder accessible by the application pool account under which the web service runs. This means that an unauthenticated remote attacker can potentially write files to locations on the server's filesystem without any user interaction or privileges. The CVSS 3.1 base score of 7.5 reflects the network attack vector (AV:N), low attack complexity (AC:L), no privileges required (PR:N), no user interaction (UI:N), unchanged scope (S:U), no confidentiality impact (C:N), high integrity impact (I:H), and no availability impact (A:N). The integrity impact is high because an attacker can modify or create files, potentially leading to code execution or manipulation of application behavior. The vulnerability affects all versions of syngo Dynamics prior to VA40G HF01, and as of the published date (November 17, 2022), no public exploits are known in the wild. However, the lack of authentication and user interaction requirements makes exploitation feasible remotely, increasing the risk of compromise. Given the nature of the vulnerability, an attacker could write malicious scripts, configuration files, or replace legitimate files, potentially leading to further compromise of the medical imaging system or the underlying host. This could disrupt clinical workflows, compromise patient data integrity, or serve as a foothold for lateral movement within healthcare networks. Siemens has not provided direct patch links in the provided data, but remediation would involve applying the fixed version VA40G HF01 or later, which presumably corrects the access control flaw in the web service operation.

For European healthcare organizations, this vulnerability poses a significant risk due to the critical role of syngo Dynamics in medical imaging and diagnostics. Exploitation could lead to unauthorized modification of imaging data or system files, undermining the integrity of diagnostic results and potentially impacting patient care decisions. Additionally, since the vulnerability allows writing files without authentication, attackers could implant malware or ransomware, leading to operational disruptions and data integrity issues. The healthcare sector is a high-value target in Europe, often subject to stringent data protection regulations such as GDPR. A breach exploiting this vulnerability could result in regulatory penalties, reputational damage, and loss of patient trust. Furthermore, compromised imaging systems could be leveraged as entry points for broader network intrusions, threatening other critical hospital infrastructure. The impact extends beyond confidentiality since the vulnerability does not directly expose data but severely affects integrity, which is paramount in medical contexts. Availability is not directly impacted by this vulnerability, but secondary effects from exploitation (e.g., malware deployment) could cause downtime. Given the interconnected nature of European healthcare networks and the criticality of medical imaging, the potential impact is high.

1. Immediate application of the vendor-provided patch or upgrade to syngo Dynamics version VA40G HF01 or later is the primary mitigation step to remediate the improper write access control. 2. Until patching is possible, restrict network access to the syngo Dynamics application server’s web service by implementing network segmentation and firewall rules that limit exposure to trusted management or clinical networks only. 3. Monitor file system changes on the syngo Dynamics server, especially in directories accessible by the application pool account, using host-based intrusion detection systems (HIDS) or file integrity monitoring tools to detect unauthorized file writes. 4. Employ strict access control policies on the server to minimize the privileges of the application pool account, ensuring it has the least privilege necessary to operate, thereby limiting the scope of writable directories. 5. Conduct regular security audits and vulnerability scans focused on medical imaging infrastructure to identify unpatched systems. 6. Implement comprehensive logging and alerting on the web service operations to detect anomalous or unexpected write requests. 7. Educate IT and security teams in healthcare organizations about this specific vulnerability and encourage rapid response to Siemens advisories. 8. Consider deploying web application firewalls (WAF) with custom rules to detect and block suspicious file write attempts targeting the vulnerable operation.