AgentTesla is known for stealing data from different applications on victim machines, such as browsers, FTP clients, and file downloaders. A new addition to this toolkit is the capability to steal WiFi profiles. In the past 2 months, it was actively distributed through spam campaigns in different formats, such as ZIP, CAB, MSI, IMG files, and Office documents. The executable (ReZer0V2) also has a resource that is encrypted. After doing several anti-debugging, anti-sandboxing, and anti-virtualization checks, the executable decrypts and injects the content of the resource into itself. The second payload (owEKjMRYkIfjPazjphIDdRoPePVNoulgd) is the main component of AgentTesla that steals credentials from browsers, FTP clients, wireless profiles, and more. To collect wireless profile credentials, a new “netsh” process is created by passing “wlan show profile” as argument. Available WiFi names are then extracted by applying a regex: “All User Profile * : (?<profile>.*)”, on the stdout output of the process. In addition to WiFi profiles, the executable collects extensive information about the system, including FTP clients, browsers, file downloaders, and machine info (username, computer name, OS name, CPU architecture, RAM) and adds them to a list. Collected information forms the body section of a SMTP message in html format:
Here’s the entire workflow:
Since AgentTesla added the WiFi-stealing feature, the threat actors may be considering using WiFi as a mechanism for spread, similar to what was observed with Emotet. Another possibility is using the WiFi profile to set the stage for future attacks.