Executive Summary
There has been a significant decrease in social engineering attacks linked to the Black Basta ransomware group since late December 2024. This lapse also included the leaked Black Basta chat logs in February 2025, indicating internal conflict within the group. Despite this, Rapid7 has observed sustained social engineering attacks. Evidence now suggests that BlackSuit affiliates have either adopted Black Basta’s strategy or absorbed members of the group. The developer(s) of a previously identified Java malware family, distributed during social engineering attacks, have now been assessed as likely initial access brokers, having potentially provided historical access for Black Basta and/or FIN7 affiliates.
Figure 1. Confirmed malicious chat requests, Feb 12 through May 7, as observed by Rapid7.
Overview
The first stage of the attack remains the same. The operator will flood targeted users with a high volume of emails, to the order of thousands per hour. This is often accomplished by signing the target user’s email up to many different publicly available mailing lists at once, effectively creating a denial of service attack when each service sends a welcome email. This technique is commonly known as an email bomb.
Following the email bomb, the strategy then splits between operators, though they all ultimately reach out to impacted users pretending to be a member of the targeted organization’s help desk. The majority of operators still perform this step via Microsoft Teams using either a default Azure/Entra tenant (i.e., email account ends with onmicrosoft[.]com) or their own custom domain. In rare cases however, operators, particularly those affiliated with BlackSuit, may forgo Microsoft Teams in favor of calling the targeted users directly with a spoofed number. This strate ..
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