The ever-evolving landscape of cybersecurity has presented users with a new and sophisticated phishing technique that exploits Microsoft Visio and SharePoint to perpetrate a two-step phishing attack. This method underscores the rapid advancements in phishing tactics by taking advantage of the inherent trust users place in widely used Microsoft tools, effectively bypassing standard security measures to steal credentials.
The attack begins with cybercriminals using compromised email accounts to send out seemingly legitimate emails, often disguised as business proposals or purchase orders. These emails contain links to Microsoft Visio (.vsdx) files hosted on SharePoint, a file format typically employed for professional flowcharts and diagrams. Upon clicking the link, users are directed to a SharePoint page containing the malicious Visio file. The file prompts users to click a "View Document" button while holding down the Ctrl key, a technique designed to circumvent automated security scans by requiring human interaction.
Once users follow these instructions, they are redirected to a fraudulent Microsoft 365 login page where their credentials are stolen if entered. This multi-layered attack leverages legitimate Microsoft services and compromised email accounts to enhance its authenticity, making it a particularly deceptive and effective phishing method. Researchers from Perception Point have noted a significant increase in Visio-based phishing attacks, impacting hundreds of organizations worldwide. One reason for their effectiveness is that Visio files are less likely to trigger alerts from traditional security systems compared to more common file types like PDFs or Word documents.
In response to this growing threat, Microsoft has acknowledged the rising misuse of its services in phishing campaigns, highlighting the pressing need for heightened vigilance. To counter these evolving threats, experts recommend verifying the identities of email senders, enabling multi-factor authentication, and deploying advanced email security solutions capable of detecting unusual file types and behaviors. This new threat serves as a stark reminder of the ongoing need for user education and robust multi-layered security defenses in an increasingly complex cyber threat landscape.