This threat involves a phishing attack technique that abuses Microsoft Excel Internet Query Files (IQY files). IQY files are used by Excel to fetch data from external web sources and import it directly into spreadsheets. Attackers exploit this functionality by crafting malicious IQY files that, when opened by a user, initiate a connection to a remote server controlled by the attacker. This connection can be used to download malicious payloads, steal credentials, or perform other malicious activities. The phishing aspect typically involves convincing users to open these IQY files, often sent as email attachments or links, under the guise of legitimate business or personal communications. Because IQY files are less commonly scrutinized compared to traditional Office macros or executable attachments, they can bypass some security controls and user suspicion. The technique leverages social engineering to induce user interaction, as the user must open the IQY file in Excel for the attack to proceed. While no known exploits in the wild have been reported at the time of publication, the method represents a medium-level threat due to its potential to bypass traditional defenses and the widespread use of Excel in organizations. The threat is linked to the Necurs botnet, known for distributing various malware and phishing campaigns, indicating a credible attack vector. Overall, this phishing technique exploits a legitimate Excel feature to deliver malicious content, requiring user interaction and social engineering to succeed.

For European organizations, this threat poses a significant risk primarily through social engineering and the abuse of trusted productivity tools like Microsoft Excel. Successful exploitation can lead to unauthorized data access, credential theft, or the initial compromise vector for more advanced malware infections. Given the widespread use of Excel across industries in Europe, including finance, manufacturing, and government sectors, the potential impact includes data breaches, financial fraud, and disruption of business operations. The indirect consequences may involve regulatory penalties under GDPR if personal data is compromised, reputational damage, and increased incident response costs. The medium severity reflects the need for user interaction and the absence of automated exploitation, but the threat remains relevant due to the sophistication of phishing campaigns and the challenge in detecting malicious IQY files. Organizations with less mature security awareness programs or insufficient email filtering may be particularly vulnerable.

To mitigate this threat effectively, European organizations should implement a combination of technical controls and user awareness measures tailored to the specific abuse of Excel IQY files. First, deploy advanced email filtering solutions capable of detecting and blocking IQY files or suspicious attachments, including sandboxing to analyze file behavior before delivery. Configure Microsoft Office security settings to disable or restrict external data connections in Excel by default, or prompt users with clear warnings when IQY files attempt to fetch data from the internet. Implement endpoint protection solutions that monitor and block unusual network connections initiated by Office applications. Conduct targeted security awareness training emphasizing the risks of opening unsolicited attachments, especially those with uncommon file extensions like .iqy, and encourage verification of unexpected requests through alternative communication channels. Additionally, maintain up-to-date threat intelligence feeds to detect campaigns associated with the Necurs botnet and related phishing activities. Finally, establish incident response procedures to quickly isolate and remediate infections stemming from such phishing attempts.