A brand new malware marketing campaign concentrating on Brazilian customers has emerged, utilizing WhatsApp as its major distribution channel to unfold banking trojans and harvest delicate data.
This subtle assault leverages social engineering by exploiting the belief victims place of their current contacts, making the malicious information seem legit.
The marketing campaign begins with phishing emails containing archived VBS scripts that make use of superior obfuscation strategies to evade detection by safety software program.
As soon as the preliminary payload runs, it downloads and installs Python and the Selenium WebDriver elements, enabling automated interplay with WhatsApp Net.
The malware then injects malicious JavaScript code into the sufferer’s browser session, accessing WhatsApp’s inside APIs to enumerate contacts and distribute payloads.
This strategy permits attackers to unfold the an infection with out requiring QR code authentication by hijacking current logged-in periods by copying browser cookies and native storage knowledge.
K7 Safety Labs researchers recognized this variant as a part of the broader Water-Saci marketing campaign, which has been actively concentrating on monetary establishments throughout Brazil.
The assault chain deploys each a Python-based distribution script and a banking trojan that screens for energetic Home windows associated to Brazilian banks and cryptocurrency wallets.
By combining automated messaging with memory-only payload execution, the malware stays undetected, primarily whereas compromising sufferer machines and their total contact networks.
The marketing campaign additionally delivers an MSI installer that drops an AutoIt script alongside encrypted payload information. This secondary part establishes persistence via registry modifications and constantly screens the sufferer’s energetic home windows for banking-related key phrases.
Kill chain (Supply – K7 Safety Labs)
When particular monetary establishments or crypto pockets purposes are detected, the malware decrypts and masses its banking trojan instantly into reminiscence, bypassing disk writes and making conventional file-based detection strategies ineffective.
Technical Breakdown of the An infection Mechanism
The an infection begins when victims obtain phishing emails containing ZIP-archived VBS script information that use character encoding and XOR encryption to evade signature-based detection.
The script employs a multi-layered obfuscation technique, constructing strings character by character utilizing Chr() capabilities after which making use of XOR operations with particular values to decode the precise malicious instructions.
objyAQeaOCCI = objyAQeaOCCI & Chr(49)objyAQea0cCI = objyAQeaOCCI & Chr(55)objyAQea0cCI = objyAQeaOCCI & Chr(57)For Every varcBAIRFO In Cut up(strSwQRHTeBd, aOwTbJaE)objhiCebPk = (objhiCebPk (26 Xor 93)) Mod 256objhiCebPk = (objhiCebPk (150 Xor 104)) Mod 256
Char and Xor (Supply – K7 Safety Labs)
After deobfuscation, the script downloads two elements: an MSI file and one other VBS file. The downloaded VBS file incorporates an identical obfuscation patterns and drops a batch script that installs the Python, ChromeDriver, and Selenium packages.
This automated setup creates the infrastructure wanted for WhatsApp automation with out requiring guide person intervention.
The Python script, named whats.py, takes management of the sufferer’s WhatsApp Net session by copying browser profile knowledge, together with cookies, native storage, and IndexedDB information, to a short lived listing.
Utilizing Selenium’s user-data-dir argument, the script launches Chrome with these copied credentials, successfully bypassing the QR code authentication step that may normally shield WhatsApp Net entry.
arquivos_copiar = [“Cookies”, “Cookies-journal”,“Local Storage”, “Session Storage”,“IndexedDB”, “Service Worker”]choices.add_argument(f”–user-data-dir={perfil_temp}”)
Units up the user-data-dir (Supply – K7 Safety Labs)
As soon as authenticated, the malware injects helper JavaScript from GitHub into the WhatsApp Net web page context, enabling entry to inside API capabilities like WPP.contact.listing, WPP.chat.sendTextMessage, and WPP.chat.sendFileMessage.
The script then harvests the sufferer’s contact listing, filtering out teams, enterprise accounts, and contacts with particular quantity patterns configured by the attackers.
These harvested contacts are batched and systematically despatched malicious ZIP information containing the following stage of the an infection, perpetuating the marketing campaign throughout sufferer networks whereas sending detailed logs again to the attacker’s PHP server.
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