Researchers at Area 1 Security have warned of a large spear phishing campaign targeting financial departments and C-suite employees with spoofed Microsoft 365 login pages. The researchers say that in some cases the attackers “specifically targeted newly-selected CEOs during critical transitionary periods.” Additionally, the attackers went after executives’ assistants.

“Beyond financial departments, the attackers also targeted C-suite and executive assistants,” Area 1 says. “Targeting high-level assistants is an often overlooked method of initial entry, despite these employees having access to highly sensitive information and an overall greater level of privileges. In a few instances, the attackers even attempted to bait newly-selected CEOs of two major companies before any public announcements of this significant senior executive changeover were made.”

The attackers appear to have been attempting to conduct business email compromise scams.

“A large majority of the phishing attacks stopped by Area 1 Security were headed to financial controllers and treasurers at various international companies,” the researchers write. “By targeting the financial departments of these companies, the attackers could potentially gain access to sensitive data of third parties through invoices and billing, commonly referred to as a BEC (Business Email Compromise) attack. This enables the attackers to send forged invoices from legitimate email addresses to suppliers, resulting in payments being made to attacker-owned accounts.”

The researchers note that the phishing emails were able to bypass email security measures, and the attackers seem to have been more sophisticated than most cybercriminals.

“Clever tactics were used to not only craft the phishing messages, but also to send those messages, as well as to obtain passwords,” the researchers write. “These methods utilized a number of techniques at every step — including legitimate-looking domains and login pages, plus advanced phishing kits — to bypass email authentication and Microsoft’s email defenses. It’s clear that the masterminds behind these attacks possess above-average skills compared to your typical credential harvesting schemers.”

New-school security awareness training can enable your employees to thwart targeted social engineering attacks.