In July 2024, eSentire’s Threat Response Unit (TRU) detected a sophisticated phishing attack that ultimately led to the infection of a system with the 0bj3ctivity Stealer malware. The attack began with a user clicking on a link to a Discord CDN, which triggered the execution of a malicious JavaScript file named Enquiry-Dubai.js. This file contained an encrypted PowerShell script designed to fetch and execute additional payloads, including the Ande Loader, which in turn facilitated the installation of the 0bj3ctivity Stealer. The entire attack chain was orchestrated using obfuscation, anti-debugging, and anti-analysis techniques to make it harder for security researchers to detect and analyze the malware.
The Ande Loader payload used by the attackers played a crucial role in maintaining persistence and furthering the infection. It utilized a method to modify the system’s registry, ensuring that the malicious script would run every time the system booted. The loader downloaded additional payloads from a remote server and performed process injection through Process Hollowing into a legitimate process, AddInProcess32.exe. This method ensured the malware could operate undetected in the system’s memory, significantly complicating detection efforts by traditional antivirus software. The downloaded payload also fetched the final malware component—the 0bj3ctivity Stealer.
Once installed, the 0bj3ctivity Stealer was able to harvest sensitive data from various sources, including web browsers, messaging applications, and other system files. It specifically targeted information such as login credentials, credit card details, and system configurations. The malware then exfiltrated this stolen data through multiple channels. It first attempted to send the data to a Telegram bot controlled by the attackers, but if that failed, it resorted to sending the data to command-and-control (C2) servers or through SMTP servers. The stealer’s ability to avoid detection was enhanced by its use of local decryption methods for password extraction and its checks for virtualized environments, which could indicate that the malware was being analyzed in a sandbox or a controlled environment.
The attackers behind the 0bj3ctivity Stealer utilized a variety of methods to ensure the success of their attack. The stealer performed checks for common debugging tools and virtualized environments, terminating itself if it detected any of these indicators. It also scanned for specific patterns to identify credit card numbers from major financial institutions, using pre-defined regular expressions for different card types. The malware exfiltrated large volumes of data from infected machines, including browser history, credentials, and even private files like Skype and Telegram chat logs. By the time eSentire’s team identified the attack, they were able to trace some of the exfiltrated data to a Telegram bot and link the attack to previous campaigns involving other malware strains like Agent Tesla RAT. This case highlights the evolving capabilities of cybercriminals to bypass security measures and extract highly sensitive data.
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