CVE-2025-20085 is a vulnerability classified under CWE-306 (Missing Authentication for Critical Function) found in Socomec DIRIS Digiware M-70 firmware version 1.6.9. The flaw exists in the Modbus RTU over TCP implementation, a protocol commonly used in industrial control systems for communication between devices. An attacker can send a specially crafted network packet without any authentication to the device, triggering a denial of service condition. More critically, this exploit can weaken the device's credential protections, causing it to revert to default documented credentials. This effectively allows unauthorized access to the device, compromising confidentiality and integrity of the system. The vulnerability does not require any privileges or user interaction, making it remotely exploitable over the network. The scope of impact is significant as the device is used in monitoring and controlling electrical distribution systems, where unauthorized access could lead to manipulation or disruption of critical infrastructure. Although no public exploits are currently known, the vulnerability's characteristics suggest it could be weaponized by attackers targeting industrial environments. The CVSS v3.1 base score of 7.2 reflects the network attack vector, low attack complexity, no privileges required, no user interaction, and a scope change due to credential weakening. The lack of available patches at the time of disclosure increases the urgency for organizations to implement compensating controls.

For European organizations, especially those in energy, manufacturing, and critical infrastructure sectors, this vulnerability poses a significant risk. Exploitation can lead to denial of service, disrupting monitoring and control operations, which may cause operational downtime or safety hazards. The weakening of credentials to default documented values increases the risk of unauthorized access, potentially allowing attackers to manipulate device settings or gather sensitive operational data. This can undermine the confidentiality and integrity of industrial control systems, potentially leading to broader network compromise or sabotage. Given the reliance on Modbus protocol in many European industrial environments, the vulnerability could affect a wide range of operational technology deployments. The impact is heightened in countries with extensive industrial automation and critical infrastructure networks, where such devices are integral to daily operations. Additionally, the lack of authentication enforcement may facilitate lateral movement within networks if attackers gain initial access, increasing the overall threat landscape.

Immediate mitigation steps include isolating the affected DIRIS Digiware M-70 devices from untrusted networks and restricting Modbus RTU over TCP traffic to trusted management stations only. Network segmentation should be enforced to limit exposure of these devices to potential attackers. Implement strict firewall rules to block unauthorized access to the Modbus TCP port. Continuous monitoring and anomaly detection on Modbus traffic can help identify exploitation attempts early. Since no patches are currently available, organizations should engage with Socomec for updates and apply firmware updates promptly once released. Additionally, changing default credentials on all devices and enforcing strong authentication mechanisms where possible can reduce risk. Employing network intrusion detection systems (NIDS) with industrial protocol awareness can provide additional defense layers. Finally, conducting regular security assessments and penetration testing on industrial control systems will help identify and remediate similar vulnerabilities proactively.