According to Trend Micro researcher Armando Nathaniel Pedragosa, the new version of Dridex uses a special technique to deliver documents with malicious macros to users without having to disguise them as any business documents.
Dridex (also known as Bugat and Cridex) is an infostealer that collects sensitive data from infected devices and downloads and deploys malicious modules. The development of the malware is attributed to the Evil Corp group (aka Indrik Spider).
Dridex is also considered the successor to the Gameover Zeus, which was developed from the infamous Zeus. In previous campaigns using this malware, attackers sent phishing emails to Windows users containing Excel files with malicious macros inside.
Analysis of Dridex samples by Trend Micro revealed the Mach-O executable, the earliest version of which appeared on VirusTotal in April 2019. Since then, 67 more artifacts have been discovered in the wild, some of them in December 2022. The discovered artifacts contained documents with an Auto-Open macro that runs automatically when a file is opened. This can be done by overwriting all DOC files in the user's directory and adding to them the malicious code extracted from the Mach-O file as a hex dump.
Macros added to overwritten documents contact a remote server to obtain additional files. And the executable tries to download the Dridex dropper to the compromised computer.