Self-Propagating Malware Spreading Via WhatsApp, Targets Brazilian Users | Trend Micro (US)

SUMMARY :

SORVEPOTEL has been observed to spread across Windows systems through convincing phishing messages with malicious ZIP file attachments. Interestingly, the phishing message that contains the malicious file attachment requires users to open it on a desktop, suggesting that threat actors might be more interested in targeting enterprises rather than consumers. Once opened, the malware automatically propagates via WhatsApp Web, causing infected accounts to be banned due to excessive spam activity.

OPENCTI LABELS :

powershell,phishing,malware,brazil,lnk file,telegram,loader,persistence,whatsapp,c server,format,whatsapp web,water saci,bradesco,brazilian,turn,watsonclient,sorvepotel


AI COMMENTARY :

1. Introduction to a New Threat in Brazil The cybersecurity landscape is witnessing a concerning escalation with the emergence of SORVEPOTEL, a self-propagating malware campaign that specifically targets Brazilian users and enterprises. Identified by Trend Micro (US), this threat leverages the immense popularity of WhatsApp and the familiarity of ZIP file attachments to infiltrate unsuspecting Windows systems. Early signs suggest that threat actors are banking on the trust users place in instant messaging platforms to bypass traditional email filters and antivirus checks, turning everyday communication channels into a launchpad for sophisticated cyberattacks.

2. The Role of Phishing and Malicious Attachments At the heart of the SORVEPOTEL operation lies a well-crafted phishing message designed to convince recipients to download a ZIP archive containing a Windows LNK file. The lure typically references well-known Brazilian entities such as Bradesco or other national brands to appear credible. Upon extraction, the LNK file triggers a PowerShell script which downloads the loader component of the malware from a remote C server. This emphasis on desktop execution reveals the adversary’s preference for corporate targets, where a successful breach can yield far greater rewards than consumer-level infections.

3. Propagation via WhatsApp Web Once the loader establishes persistence on the compromised machine, it automatically initiates a secondary module that leverages WhatsApp Web. By hijacking the user’s active session or prompting a new login through WatsonClient techniques, the malware sends malicious links or ZIP attachments to the victim’s contacts list. This rapid, peer-to-peer propagation results in countless infected accounts pushing the limits of spam detection systems, often leading to account suspension. Such excessive messaging also increases noise, making detection by security teams more challenging while the threat continues to spread unchecked.

4. Technical Deep Dive and Persistence Mechanisms The SORVEPOTEL malware employs a multi-layered approach to maintain persistence and evade detection. Following the initial PowerShell execution, it drops additional payloads in hidden directories while modifying registry keys to ensure auto-start on reboot. A combination of obfuscation and anti-analysis tricks shields the loader from sandbox environments. Furthermore, the command-and-control channel utilizes a custom protocol over HTTPS to blend in with legitimate traffic. The use of advanced formatting and encryption within messages complicates network monitoring, giving attackers ample time to relay commands or exfiltrate data.

5. Insights into Targeting and Motivation Although consumers in Brazil are not immune, the focus on enterprise targets is evident from the tailored social engineering lures referencing corporate departments, financial services, and internal communications tools. References to ‘water saci’ rumors or localized events increase the perceived legitimacy of the messages. Threat actors appear to be testing reconnaissance and lateral movement techniques under the guise of a seemingly innocent chat-based exchange. This dual-use of Telegram channels for initial intel gathering and WhatsApp for propagation highlights a well-coordinated campaign aimed at harvesting credentials and potentially deploying secondary attacks within compromised networks.

6. Mitigation Strategies and Best Practices To defend against SORVEPOTEL and similar threats, organizations must reinforce their email and messaging security policies. Enabling strong authentication for WhatsApp Web, regularly auditing active sessions, and educating employees on the dangers of opening unsolicited ZIP files are critical steps. Deploying endpoint protection solutions that monitor PowerShell activity and detect unusual script executions can halt the malware before it establishes persistence. Network teams should also implement SSL/TLS inspection and behavioral analysis to identify encrypted C2 traffic. By combining user awareness with layered defensive controls, enterprises can minimize the risk posed by this rapidly evolving self-propagating malware.


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Self-Propagating Malware Spreading Via WhatsApp, Targets Brazilian Users | Trend Micro (US)