Threat actors have been increasingly exploiting Cloudflare’s TryCloudflare feature to deliver various remote access trojans (RATs), including AsyncRAT, GuLoader, Remcos, VenomRAT, and Xworm, according to a report by Proofpoint. Since February 2024, these attackers have been using Cloudflare’s one-time tunnel creation capability, which allows them to establish temporary connections without requiring an account. This method has been leveraged to distribute malware through phishing campaigns that often involve deceptive messages and attachments leading to URLs for tunnel establishment.
The attacks typically involve phishing messages written in multiple languages, such as English, French, German, and Spanish, and cover topics relevant to business operations, including document requests, invoices, deliveries, and taxes. Once the link in the phishing message is accessed, it initiates a multi-stage infection process that downloads and installs the malware payload. Each campaign can involve different Python scripts leading to various malware types, demonstrating the attackers’ adaptability and sophistication.
Proofpoint’s findings indicate that these phishing campaigns range from hundreds to tens of thousands of messages, impacting a significant number of organizations globally. The consistent use of specific tactics, techniques, and procedures (TTPs) throughout these campaigns suggests that the attacks are orchestrated by a single threat actor or a coordinated group. Despite this, the specific threat actor behind these activities has not yet been identified.
The abuse of Cloudflare tunnels offers attackers a flexible, temporary infrastructure that complicates detection and defense efforts. This approach allows attackers to rapidly deploy and dismantle malicious instances, making traditional security measures, such as static blocklists, less effective. The rising trend of using Cloudflare’s services for malware delivery highlights the need for enhanced security measures and vigilance against evolving cyber threats.
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