The threat described is a malspam campaign from May 27, 2016, distributing the Locky ransomware via malicious JavaScript files (.js) compressed inside ZIP archives. Locky ransomware is a type of malicious software that encrypts victims' files and demands a ransom payment for the decryption key. The infection vector in this campaign involves sending emails with ZIP attachments containing obfuscated JavaScript files. When the user extracts and executes the .js file, the script downloads and installs the Locky ransomware payload on the victim's machine. Locky ransomware typically encrypts a wide range of file types, rendering them inaccessible, and appends a unique extension to encrypted files. It then displays ransom notes instructing victims on how to pay the ransom, usually in Bitcoin, to regain access to their data. The campaign leverages social engineering by enticing users to open attachments that appear legitimate or urgent. Although the severity is marked as low in the provided data, Locky ransomware historically caused significant disruption due to its widespread distribution and effective encryption. The threat level of 3 indicates a moderate concern, but the absence of known exploits in the wild at the time suggests limited active exploitation. However, the use of JavaScript in ZIP files as an infection vector is notable because it can bypass some email security filters and relies heavily on user interaction to execute the malicious code. This campaign highlights the ongoing risk of ransomware spread via email attachments and the importance of user awareness and technical controls to prevent execution of malicious scripts.

For European organizations, the impact of this Locky ransomware campaign could be substantial despite the low severity rating in the original report. Ransomware infections can lead to significant operational disruption by encrypting critical business data, causing downtime, loss of productivity, and potential financial losses from ransom payments or recovery efforts. Confidentiality is also at risk if attackers exfiltrate data before encryption, although this is not explicitly stated here. The integrity and availability of data are directly compromised due to encryption. European organizations with limited email security controls or insufficient user training are particularly vulnerable to such malspam campaigns. Additionally, sectors with critical infrastructure or sensitive data, such as healthcare, finance, and government, could face severe consequences if infected. The campaign's reliance on user interaction means that organizations with strong security awareness programs may reduce their risk, but the threat remains significant given the potential for widespread infection and disruption.

To mitigate this threat, European organizations should implement multi-layered defenses beyond generic advice: 1) Deploy advanced email filtering solutions that can detect and quarantine ZIP attachments containing JavaScript files or other executable content. 2) Configure email gateways to block or flag suspicious file types, especially .js files within compressed archives. 3) Enforce strict endpoint protection policies that prevent execution of scripts from email attachments or untrusted sources. 4) Conduct targeted user awareness training focusing on the dangers of opening unexpected attachments, especially ZIP files containing scripts. 5) Implement application whitelisting to restrict execution of unauthorized scripts and binaries. 6) Maintain up-to-date backups with offline or immutable storage to enable recovery without paying ransom. 7) Monitor network traffic for indicators of compromise related to Locky ransomware, such as connections to known command-and-control servers. 8) Employ network segmentation to limit ransomware spread if infection occurs. 9) Regularly update and patch systems to reduce vulnerabilities that ransomware might exploit post-infection. These specific measures address the infection vector and ransomware behavior to reduce risk effectively.