This threat pertains to a malspam campaign identified on September 14, 2016, which distributes malware via email attachments. The campaign uses a social engineering lure themed around "Tax invoice" to entice recipients to open a compressed ZIP file containing a Windows Script File (.wsf). The .wsf file format is capable of executing scripts on Windows systems, which can be leveraged by attackers to run malicious code once the user opens the attachment. The use of a .zip archive is a common tactic to bypass email security filters that scan for executable files directly. Although the specific malware payload and its capabilities are not detailed in the provided information, the campaign's objective is likely to infect systems with malware that could range from information stealers to remote access trojans or ransomware. The campaign is classified as malware with a low severity rating by the source, and there are no known exploits in the wild beyond the malspam distribution itself. The threat level is indicated as 3 on an unspecified scale, and no further technical analysis or indicators of compromise are provided. Given the age of the campaign (2016), it likely targeted Windows environments prevalent at that time, relying on user interaction to open the malicious attachment and execute the script.

For European organizations, the impact of this malspam campaign depends largely on user susceptibility to social engineering and the effectiveness of existing email security controls. If successful, the malware could compromise confidentiality by stealing sensitive data, impact integrity by modifying or corrupting files, or affect availability through destructive payloads or ransomware. The campaign's use of a tax invoice theme is particularly relevant in Europe, where tax documentation is a common business process, potentially increasing the likelihood of user engagement. However, given the low severity rating and lack of known active exploitation beyond the initial campaign, the overall risk is moderate to low for well-defended organizations. Nonetheless, organizations with insufficient email filtering, outdated endpoint protection, or limited user awareness training could face operational disruptions, data breaches, or financial losses if infected.

To mitigate this threat effectively, European organizations should implement advanced email filtering solutions capable of detecting and quarantining compressed archives containing potentially malicious script files like .wsf. Endpoint protection platforms should be configured to monitor and block the execution of script files originating from email attachments or untrusted sources. User awareness training must emphasize the risks of opening unsolicited attachments, especially those purporting to be tax-related documents. Organizations should enforce strict policies on handling compressed email attachments and consider disabling Windows Script Host where feasible or restricting script execution via application whitelisting. Regular patching of operating systems and security software is essential to reduce the attack surface. Additionally, network monitoring for unusual outbound connections can help detect post-infection command and control activity. Incident response plans should include procedures for malspam campaigns and malware infections to minimize impact.