Three groups from the disbanded Conti ransomware gang are using call-back phishing technique to gain initial access to targeted networks. The advanced social engineering tactic used by the attackers is called BazaCall (BazarCall).
The three groups include Silent Ransom, Quantum and Roy / Zeon.
BazarCall is a unique phishing attack because it uses phone numbers to trick recipients into calling after being alerted to an imminent charge on their credit card for a premium subscription. This method is therefore different from the normal phishing attack where malicious links are attached to emails.
If the victim decides to call the phone number given in the email, a real person from a fraudulent call center set up by BazaCall’s operators picks and try to persuade them to give the customer service person a remote control of the desktop to help with the cancellation of the alleged subscription.
By accessing the desktop, the threat actor secretly takes steps to infiltrate the user’s network and establish persistence for follow-up activities such as data exfiltration.
“Three autonomous threat groups have since adopted and independently developed their own targeted phishing tactics derived from the call back phishing methodology. Call back phishing was the tactic that enabled a widespread shift in the approach to ransomware deployment. Attack vector is intrinsically embedded into the Conti organizational tradition,” cybersecurity firm AdvIntel said.
The sources for this piece include an article in TheHackerNews.