Hackers have weaponized Word documents to steal login credentials using a malware dubbed “CarnavalHeist.” According to cybersecurity researchers at Cisco Talos, CarnavalHeist specifically targets Brazilian users, leveraging the widespread use and trust of Word documents to deceive victims into opening them. The malware is distributed through invoice-themed emails containing shortened URLs that redirect users to fake invoice websites. These websites download a malicious LNK file via WebDAV, which runs the next stage payload.
CarnavalHeist employs advanced social engineering techniques by extensively using Portuguese terms and targeting Brazilian financial institutions. The malware shows a false PDF document to mislead users while executing malicious code in the background. It utilizes obscured Python scripts, dynamically generated domains, and DLL injections to load a banking Trojan payload. This Trojan captures credentials, screenshots, videos, and enables remote access, with capabilities such as generating QR codes to steal transactions.
The malware campaign has been active since at least November 2023, with increased activity noted from February 2024. The command and control infrastructure is hosted in Microsoft Azure’s BrazilSouth region, and the malware uses a domain generation algorithm (DGA) to create subdomains for downloading payloads and communications. CarnavalHeist’s activities highlight the evolving threat landscape and the persistent efforts of attackers to develop sophisticated methods for compromising victims’ systems and stealing sensitive data.
Cisco Talos continues to identify new samples of CarnavalHeist, emphasizing the need for organizations and individuals to remain vigilant and implement robust cybersecurity measures to protect against such threats. Users are advised to be cautious when opening unsolicited emails and to keep their systems updated with the latest security patches to mitigate the risk of malware infections.
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