Banking Trojan Chaes Installs Malicious Chrome Extensions

Chaes banker’s large-scale campaign was discovered, during which about 800 WordPress sites were compromised. The Trojan mainly targets Brazilian users and uses five malicious extensions for the Chrome browser in its attacks.

Chaes activity was discovered by Avast experts, who report that a new malware campaign started at the end of 2021. Initially, the malware was discovered back in 2020 by Cybereason analysts, and then (as now) it was aimed at customers of Banco do Brasil, Loja Integrada, Mercado Bitcoin, Mercado Livre and Mercado Pago banks.

Now the researchers say the attack starts when the victim visits one of the hacked sites. There, the user sees a pop-up window asking to install a fake Java Runtime application.

Banking Trojan Chaes

The MSI installer for this “app” contains three malicious files (install.js, sched.js, sucesso.js) that prepare the Python environment for the next stage loader. If the user follows the instructions, the malware initiates a complex bunker delivery procedure, which ends with the deployment of several modules – including spyware and remote-access module.

Banking Trojan Chaes

Chays is characterized by multi-stage delivery, which involves environments such as JScript, Python and NodeJS, as well as binaries written in Delphi, and malicious extensions for Google Chrome. The ultimate goal of Chaes is to steal credentials stored in Chrome, as well as intercept logins and passwords from popular banking in Brazil. the researchers say.

Some intermediate payloads are not only encrypted, but also hidden in commented code inside the HTML pages of the awsvirtual[.]blogspot.com domain. At the final stage of the attack, the JavaScript dropper downloads and installs up to five malicious Chrome extensions on the victim’s system:

  1. Online – Delphi module used to fingerprint the victim and transfer system information to the hackers’ control server;
  2. Mtps4 (MultiTela Pascal) is a Delphi-based backdoor, the main purpose of which is to connect to the control server and wait for the response Pascal Script to be executed;
  3. Chrolog (ChromeLog) – steals passwords from Google Chrome, the module is also written in Delphi;
  4. Chronodx (Chrome Noder) is a JavaScript Trojan that, upon detecting the launch of the Chrome browser, immediately closes it and opens its own instance of Chrome containing a malicious module that steals banking information;
  5. Chremows (Chrome WebSocket) is a banking JavaScript Trojan that intercepts keystrokes and mouse clicks in Chrome to steal credentials (for Mercado Livre and Mercado Pago users).
Currently, the Chaes distribution campaign is still active and will continue until all compromised WordPress sites are secured. Avast analysts say that some of the sites that are used to deliver payloads are very popular in Brazil, so the number of infected systems is likely to be very high.

Let me remind you that we also wrote that Banking Trojan QakBot attacked over 17,000 users worldwide, and also that Anubis Android Banker Targets Nearly 400 Financial App Users.

Helga Smith

I was always interested in computer sciences, especially data security and the theme, which is called nowadays "data science", since my early teens. Before coming into the Virus Removal team as Editor-in-chief, I worked as a cybersecurity expert in several companies, including one of Amazon's contractors. Another experience: I have got is teaching in Arden and Reading universities.

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