This threat involves the Locky ransomware family, identified with an affiliate ID 3, and associated with TrickBot malware activity, specifically noted in October 2017. Locky ransomware is a well-known malware strain that encrypts victims' files and demands ransom payments for decryption. The mention of TrickBot indicates a possible delivery or secondary infection vector, as TrickBot is a modular banking Trojan often used to deploy ransomware like Locky. The reference to filenames such as "Invoice INV0000123" and "Invoice INV0000123.7z" suggests that the infection vector may involve malicious email attachments masquerading as invoice documents, a common social engineering tactic to entice users to open the file and trigger the malware execution. The ransomware likely encrypts files on infected systems, rendering them inaccessible until a ransom is paid. The technical details indicate a threat level of 3 and a low severity rating, with no known exploits in the wild at the time of reporting. The lack of affected versions and patch links suggests this is a malware campaign rather than a vulnerability in a specific software product. The threat is categorized under ransomware and malicious code, with ties to TrickBot, which is known for its capability to spread laterally within networks and steal credentials, potentially increasing the impact of the ransomware attack.

For European organizations, the impact of this Locky ransomware campaign combined with TrickBot infection can be significant. Ransomware can cause operational disruption by encrypting critical business data, leading to downtime and potential loss of revenue. TrickBot's credential theft capabilities can exacerbate the situation by allowing attackers to move laterally within networks, compromising additional systems and increasing the scope of the attack. European organizations, especially those relying heavily on digital invoicing and email communications, are at risk due to the social engineering tactics used (malicious invoice attachments). The low severity rating may reflect the threat's age and the availability of detection and mitigation tools; however, organizations that have not updated their defenses or trained employees remain vulnerable. The financial sector, healthcare, and critical infrastructure entities in Europe could face heightened risks due to the sensitive nature of their data and the potential for service disruption.

To mitigate this threat, European organizations should implement targeted measures beyond generic advice: 1) Enhance email filtering to detect and quarantine suspicious attachments, particularly those with archive extensions like .7z or unusual invoice naming patterns. 2) Conduct regular user awareness training focusing on recognizing phishing emails and the risks of opening unsolicited attachments. 3) Deploy and maintain advanced endpoint detection and response (EDR) solutions capable of identifying TrickBot and Locky behaviors, including lateral movement and file encryption activities. 4) Implement network segmentation to limit the spread of malware within internal networks. 5) Enforce the principle of least privilege to reduce the impact of credential theft by TrickBot. 6) Maintain up-to-date backups stored offline or in immutable storage to enable recovery without paying ransom. 7) Monitor network traffic for indicators of TrickBot command and control communications and block known malicious IPs and domains. 8) Regularly update and patch all systems to reduce the attack surface, even though no specific patches are linked to this threat, as TrickBot often exploits other vulnerabilities to propagate.