fast-dotenvPyPI
fast-dotenv is a confirmed malicious PyPI package (MAL-2026-10215) that steals credentials and exfiltrates sensitive data (malicious version 1.0.0). Do not install it — remove it immediately and rotate any exposed credentials.
Malicious code in fast-dotenv (PyPI)
What this malware does
The package presents itself as a.env loader but on load()/config() spawns a background thread that, after a 72–96 hour activation delay jittered by hostname hash, decodes base64-obfuscated dead-drop URLs (a GitHub gist under opensource-crypto and a GitLab snippet under devtool-labs/config-snippets) to retrieve a JSON C2 configuration (host, port, path, fallback) and POSTs collected data to https://{c2}:{port}{path}. Data collected includes host/environment identity, environment variables whose names contain key/secret/token/password/auth/private/wallet/seed/mnemonic, and an enumeration of ~/.ssh/ (id_rsa, id_ed25519, id_ecdsa, config, known_hosts). The C2 URLs are stored as base64 literals in _CONFIG_SOURCES with cover comments describing them as documentation examples, hiding the network destinations from plain-text inspection. The long dormancy, remote-configurable destination, base64-obfuscated dead drops, and cover comments together are the shape of a staged supply-chain credential stealer.
When using the library, it schedules a delayed malware activation. Malicious code contacts remote URLs to get C2 location, then performs machine fingerprinting, including looking for sensitive environmental variables and SSH keys. The code seems not to exfiltrate their content in the analyzed version. Additionally, the embeded configuration URLs did not exist, but they led to related C2 configurations from the same GitHub account, which also seems to have created repositories with similar malicious code in other languages.
Category: MALICIOUS - The campaign has clearly malicious intent, like infostealers.
Campaign: 2026-07-fast-dotenv
Reasons (based on the campaign):
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The package contains code to exfiltrate basic data from the system, like IP or username. It has a limited risk.
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exfiltration-env-variables
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exfiltration-ssh-keys
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action-hidden-in-lib-usage
Malicious versions
Indicators of compromise (SHA-256)
Detection & response playbook
Credential / info stealerFind it
Scan your lockfiles (package-lock.json, pnpm-lock.yaml, yarn.lock, requirements.txt, poetry.lock, etc.) and build artifacts for fast-dotenv (version 1.0.0). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging fast-dotenv across your stack and pipelines.
If you installed it — respond
fast-dotenv is built to steal secrets, so assume every credential the build or runtime could read is compromised. Remove it from your project and lockfile, then rotate ALL exposed secrets — npm/registry tokens, cloud keys, CI/CD secrets, SSH keys, and any .env values — from a known-clean machine. Audit logs for unauthorized use of those credentials.
Did it already run?
If fast-dotenv was ever installed, its post-install/runtime payload may have already executed. O3's L7 egress monitoring and runtime eBPF sensors detect the credential exfiltration or command-and-control callback after install and block the malicious outbound channel, so you catch and contain the actual compromise — not just the presence of the package.
How O3 protects you
O3 blocks fast-dotenv before install through its supply-chain scanner, and if it has already run, detects and severs the exfiltration or C2 callback at runtime through L7 egress monitoring and eBPF.
Frequently asked questions
Campaign
References
Credits
- Amazon Inspector · finder
- Kamil Mańkowski (kam193) · reporter
Detect & block this
O3 blocks fast-dotenv-class packages before install and in CI — and if it already ran, its runtime egress monitoring catches the credential exfiltration and severs the channel.