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Phishing campaign mimics CAPTCHA to deliver hidden malware commandsPowerShell command hidden in verification leads to Lumma Stealer attackEducating users on phishing tactics is key to preventing such attacks
CloudSek has identified a sophisticated approach to distributing the Lumma Stealer malware, which poses significant risks to Windows users.
This method leverages false human verification pages designed to deceive users into executing malicious commands unknowingly.
While the primary goal of this campaign is to circulate the Lumma Stealer malware, the techniques employed may also be adapted to deliver various other malicious software.
How the phishing campaign operates
The tactics employed include hosting phishing sites on trusted platforms like Amazon S3 and numerous Content Delivery Networks (CDNs), utilizing a modular approach to malware delivery. This structure allows an initial executable to download further components, complicating detection and analysis.
The infection process starts when attackers direct victims to these fraudulent sites resembling legitimate Google CAPTCHA verification pages. These pages are falsely presented as necessary identity checks, deceiving users into believing they are engaging in typical security measures.
Once the victim clicks the “Verify” button, the situation becomes increasingly deceptive. An unseen JavaScript function operates in the background, copying a base64-encoded PowerShell command to the user’s clipboard without their awareness. The phishing page then prompts the user to execute a peculiar series of actions, including opening the Run dialog (Win+R) and pasting the copied command. Following these instructions results in the PowerShell command executing in an invisible window, rendering detection nearly impossible for the user.
This hidden PowerShell command is central to the attack. It connects to a remote server to download further content, including a text file (a.txt) that provides instructions for obtaining and executing the Lumma Stealer malware. Once this malware is integrated into the system, it establishes communication with attacker-controlled domains, enabling the theft of sensitive data and potential escalation of malicious actions.
To mitigate the risks associated with this phishing campaign, both individuals and organizations must prioritize security awareness and adopt proactive defenses. Educating users is a critical initial step.
The deceptive nature of these attacks, disguised as legitimate verification processes, underscores the necessity of educating users on the dangers of following suspicious prompts, particularly those that require copying and pasting unknown commands. Users should be trained to identify phishing tactics and to question unexpected CAPTCHA verifications or unfamiliar instructions involving system commands.
Moreover, implementing robust endpoint protection is vital for safeguarding against PowerShell-based attacks. Given that attackers heavily rely on PowerShell for executing their malicious activities, organizations should ensure their security measures can detect and block these actions. Advanced endpoint protection systems featuring behavioral analysis and real-time monitoring can spot unusual command executions, thereby preventing malware from being downloaded and installed.
Organizations are also advised to monitor network traffic for any suspicious activity proactively. Security teams should remain vigilant regarding connections to newly registered or atypical domains, which are frequently leveraged by attackers to distribute malware or extract sensitive information.
Furthermore, regular system updates with the latest patches constitute an essential defense strategy. These updates address known vulnerabilities, thereby limiting the chances for attackers to exploit outdated software in their efforts to disseminate malware like Lumma Stealer.
“This new tactic poses a notable risk as it capitalizes on users’ trust in recognized CAPTCHA verifications encountered frequently online. By obscuring malicious actions within the guise of routine security checks, attackers can deftly mislead users into executing harmful commands on their systems. Alarmingly, this method, currently utilized for distributing Lumma Stealer, could easily be adapted to propagate various other types of malware, marking it as a highly adaptable and evolving threat,” stated Anshuman Das, a Security Researcher at CloudSEK.
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Source
www.techradar.com