Recently, Morse code was used in the phishing emails to bypass email filters and secure gateways. BleepingComputer found the attack on numerous samples uploaded on 2nd February 2021 to VirusTool. The attack starts with an invoice like files that are saved as “Revenue_payment_invoice February_Wednesday 02/03/2021” containing the HTML attachment for the invoice as [company_name]_invoice_[number]._xlsx.html.
This also uses the logo-clearbit.com service that puts the company’s logo on the form making it convincing. It also uses a generic Office 365 logo in case a logo is not available. Bridgestone, Dea Capital, Metrohm, SGS, SBI Ltd (Mauritius), etc. are a few names that have suffered because of this attack.
Morse code was invented by Alfred Vail and Samuel Morse as a means to transfer messages across telegraph lines that contain the code for the numbers and letters. The dashes are used for long sound and dots are used for short sounds in the morse code.