A threat actor published at least eight malicious forks of the Pyrogram Python library on PyPI between November 2025 and June 2026. These packages include a hidden backdoor module (secret.py) that registers Telegram command handlers to execute attacker-supplied Python code or shell commands on infected servers running Telegram bots. The backdoor allows reading arbitrary files, accessing Telegram client data, and exfiltrating information via Telegram messages. The attacker uses a hardcoded list of Telegram IDs for exclusive control and disables logging to operate stealthily. The campaign targets production Telegram bot environments to access sensitive infrastructure components. Checkmarx researchers attribute all malicious packages to a single actor based on shared code and infrastructure.

Attackers gain remote code execution on servers running infected Telegram bots, enabling them to read any file, access Telegram chats and session data, dump secrets, download databases, and install persistent backdoors. This compromises the confidentiality and integrity of the affected servers and any sensitive data they hold. The backdoor operates with the same privileges as the infected application, potentially allowing full system compromise depending on the bot's permissions.

No official patch exists as this is a supply chain malware campaign involving malicious PyPI packages. Developers should immediately remove any of the identified malicious Pyrogram forks from their environments. They must rotate all credentials on affected servers and revoke Telegram bot tokens to prevent further unauthorized access. Vigilance in verifying package authenticity before installation is critical to avoid similar supply chain threats.