The threat described relates to the Locky ransomware variant observed around September 14, 2017. Locky is a well-known ransomware family that encrypts victims' files and demands payment for decryption. This particular instance is identified with the marker ".lukitus" and references to files named like "Copy of Invoice 12345" and links such as /invoice.html, which suggests a social engineering tactic where the ransomware is distributed via malicious email attachments or links masquerading as legitimate invoices. The ransomware encrypts files on infected machines, appending extensions such as ".lukitus" to encrypted files, thereby denying access to critical data. Although the severity is marked as low in this report, Locky historically has caused significant disruption. The absence of affected versions and patch links indicates this is a generic malware report rather than a vulnerability in a specific product. No known exploits in the wild are reported for this particular sample, but Locky ransomware campaigns have been widely distributed via phishing emails. The threat level is moderate (3 out of an unspecified scale), and the technical details are limited, but the presence of ransomware implies a risk to confidentiality and availability of data. The attack vector is likely user interaction via phishing emails containing malicious attachments or links. The malware encrypts files, impacting data availability and potentially causing operational disruption.

For European organizations, the impact of Locky ransomware can be substantial. Organizations that rely heavily on digital documents, such as invoices and financial records, are particularly vulnerable due to the social engineering lure of invoice-themed emails. Successful infections can lead to encrypted critical business data, resulting in operational downtime, financial losses, and potential reputational damage. Small and medium enterprises (SMEs) with less mature cybersecurity defenses may be disproportionately affected. Additionally, sectors such as finance, healthcare, and public administration, which handle sensitive data and require high availability, face increased risks. The disruption caused by ransomware can also affect supply chains and service delivery. Although this specific variant is marked with low severity, the broader Locky ransomware family has historically caused high-impact incidents, indicating that European organizations should remain vigilant. The lack of known exploits in the wild for this sample suggests limited immediate threat, but the general ransomware threat landscape remains active and dangerous.

To mitigate the risk posed by Locky ransomware, European organizations should implement targeted measures beyond generic advice: 1) Enhance email filtering to detect and quarantine phishing emails, especially those with invoice-related subject lines or attachments. 2) Conduct regular user awareness training focused on recognizing phishing attempts and suspicious attachments or links. 3) Implement application whitelisting to prevent unauthorized execution of ransomware binaries. 4) Maintain robust, offline, and tested backups of critical data to enable recovery without paying ransom. 5) Deploy endpoint detection and response (EDR) solutions capable of identifying ransomware behaviors such as rapid file encryption and unusual file extension changes. 6) Restrict user permissions to limit the ability of ransomware to encrypt network shares or critical system files. 7) Monitor network traffic for anomalies indicative of ransomware communication or propagation. 8) Regularly update and patch all systems to reduce attack surface, even though no specific patches are noted here. These steps, combined with incident response planning, will reduce the likelihood and impact of Locky infections.