Cybersecurity researchers have uncovered a disturbing new tactic involving malicious PyPI packages that use Gmail to exfiltrate stolen data and communicate with threat actors. The discovery, made by security firm Socket, led to the removal of the infected packages from the Python Package Index (PyPI), although not before considerable damage had already occurred.

Socket reported identifying seven malicious packages on PyPI, some of which had been listed for more than four years. Collectively, these packages had been downloaded over 55,000 times. Most were spoofed versions of the legitimate "Coffin" package, with deceptive names such as Coffin-Codes-Pro, Coffin-Codes, NET2, Coffin-Codes-NET, Coffin-Codes-2022, Coffin2022, and Coffin-Grave. Another package was titled cfc-bsb.

According to the researchers, once installed, these packages would connect to Gmail using hardcoded credentials and initiate communication with a command-and-control (C2) server. They would then establish a WebSockets tunnel that leverages Gmail’s email server, allowing the traffic to bypass traditional firewalls and security systems.

This setup enabled attackers to remotely execute code, extract files, and gain unauthorized access to targeted systems.

Evidence suggests that the attackers were mainly targeting cryptocurrency assets. One of the email addresses used by the malware featured terms like “blockchain” and “bitcoin” — an indication of its intent.

“Coffin-Codes-Pro establishes a connection to Gmail’s SMTP server using hardcoded credentials, namely sphacoffin@gmail[.]com and a password,” the report says.

“It then sends a message to a second email address, blockchain[.]bitcoins2020@gmail[.]com politely and demurely signaling that the implant is working.”

Socket has issued a warning to all Python developers and users who may have installed these packages, advising them to remove the compromised libraries immediately, and rotate all sensitive credentials.

The researchers further advised developers to remain alert for suspicious outbound connections:

“especially SMTP traffic”, and warned them not to trust a package just because it was a few years old.

“To protect your codebase, always verify package authenticity by checking download counts, publisher history, and GitHub repository links,” they added.

“Regular dependency audits help catch unexpected or malicious packages early. Keep strict access controls on private keys, carefully limiting who can view or import them in development. Use isolated, dedicated environments when testing third-party scripts to contain potentially harmful code.”