Security researchers have uncovered a concerning new malware campaign targeting Python developers, utilizing an unusual and potentially stealthy method for command and control infrastructure: Cloudflare Tunnels. This attack highlights an evolving threat landscape where adversaries are leveraging legitimate services to mask malicious activity, specifically targeting the software supply chain.
The core of this attack involves distributing malicious Python packages hidden within popular repositories. These packages, once installed by unsuspecting developers, contain obfuscated or seemingly benign code that, upon execution, establishes a persistent connection to a command and control (C2) server. The novel aspect is the use of Cloudflare Tunnels for this connection.
Cloudflare Tunnels are designed to securely connect internal services to the Cloudflare network without exposing a public IP address. While a legitimate and useful tool for secure access, attackers are exploiting this feature. By running a Cloudflare Tunnel client on the compromised machine, the malware can create a secure, persistent connection back to an attacker-controlled server also using Cloudflare. This makes detection challenging because the traffic appears to be legitimate network activity connecting to Cloudflare infrastructure, potentially bypassing traditional firewall rules that might block direct connections to known malicious IP addresses.
Once the secure channel is established via the Cloudflare Tunnel, the malware can receive commands from the attacker and exfiltrate sensitive data from the compromised environment. This could include source code, credentials, configuration files, and other proprietary information, posing a significant risk to individuals and organizations alike. This technique adds a layer of obfuscation and resilience to the C2 communication, making incident response and threat hunting more complex.
This campaign underscores the critical need for enhanced security practices within the Python ecosystem and software development workflows. Developers and organizations must exercise extreme caution when integrating third-party packages. Verifying the legitimacy and integrity of packages, scrutinizing dependencies, using dependency scanning tools, and implementing strong network monitoring that can identify unusual connections – even to seemingly legitimate services like Cloudflare – are essential defensive measures. The use of Cloudflare Tunnels by malware serves as a stark reminder that attackers will constantly adapt their methods, exploiting legitimate tools in new and innovative ways to achieve their malicious goals.
Source: https://go.theregister.com/feed/www.theregister.com/2025/06/19/sneaky_serpentinecloud_slithers_through_cloudflare/
