The provided information describes a malware threat identified as Locky ransomware, specifically a variant or instance dated 2017-09-26. Locky is a well-known ransomware family that encrypts victims' files and demands ransom payments for decryption keys. The reference to ".ykcol" and filenames such as "InvoicePIS1234567.7z" suggests that the ransomware encrypts files and appends or replaces extensions with a unique marker (in this case, ".ykcol"), which is a known behavior of Locky variants. The mention of "Invoice PIS1234567" likely indicates that the ransomware targets or encrypts files resembling invoices or financial documents, which are common targets due to their importance to business operations. The threat is classified as malware with a low severity rating by the source, CIRCL, and is tagged as ransomware. No specific affected product versions or patches are listed, and there are no known exploits in the wild beyond the malware's general propagation. The technical details indicate a threat level of 3 (on an unspecified scale) and minimal analysis depth (analysis=1). Overall, this is a ransomware threat that encrypts files, potentially disrupting business operations by denying access to critical documents.

For European organizations, the impact of Locky ransomware can be significant despite the low severity rating in this report. Locky ransomware typically encrypts a wide range of file types, including business-critical documents such as invoices, contracts, and financial records. The encryption of such files can lead to operational disruption, financial loss due to ransom payments or downtime, and potential reputational damage. Additionally, organizations may face regulatory consequences under GDPR if personal data is affected and not properly recovered or if the incident is not reported timely. The ransomware's targeting of invoice-like files suggests a focus on financial data, which could impact accounting departments and supply chain operations. Although no active exploits are noted, the presence of Locky variants in the wild historically indicates a persistent threat, often spread via phishing emails or malicious attachments. European organizations with insufficient email filtering, endpoint protection, or user awareness training are at higher risk. The low severity rating may reflect the specific sample's limited impact or detection, but the general Locky ransomware family is known for causing medium to high impact incidents.

To mitigate the threat posed by Locky ransomware, European organizations should implement a multi-layered defense strategy: 1) Enhance email security by deploying advanced spam filters and sandboxing to detect and block malicious attachments or links, especially those mimicking invoices or financial documents. 2) Conduct regular user awareness training focusing on phishing and social engineering tactics to reduce the likelihood of users opening malicious files. 3) Maintain up-to-date endpoint protection solutions with behavioral detection capabilities to identify ransomware activity early. 4) Implement robust backup and recovery procedures, ensuring backups are offline or immutable to prevent ransomware encryption. 5) Apply network segmentation to limit ransomware spread if an endpoint is compromised. 6) Monitor file system activity for unusual file renaming or encryption patterns, such as the appearance of ".ykcol" extensions. 7) Establish incident response plans specifically addressing ransomware scenarios to enable rapid containment and recovery. 8) Regularly update and patch all systems to reduce the attack surface, even if no direct vulnerabilities are listed for this malware. These measures go beyond generic advice by focusing on the ransomware’s known behaviors and typical infection vectors.