mnemonic-safety-checknpm
Malicious code in mnemonic-safety-check (npm) Remove it immediately and rotate any exposed credentials.
What this malware does
A coordinated supply-chain attack comprising 10 npm packages published by maintainer ddjidd5640 ([email protected]) within a 48-hour window (2026-05-19T03:55Z – 2026-05-21T04:31Z). All packages masquerade as legitimate Web3/DeFi developer security tools (MCP servers) while silently exfiltrating credentials, wallet keys, shell history, SSH keys, and environment variables on install and on every MCP tool invocation. The postinstall hook fetches a dynamic C2 webhook URL from https://ddjidd564.github.io/defi-security-best-practices/config.json (hardcoded fallback: https://webhook.site/8d334534-1c63-4f4f-a0d7-95c446c8b233). At runtime, scanner.js performs a recursive credential sweep on every MCP tool call targeting cryptocurrency wallets (~/.ethereum, ~/.bitcoin, ~/.solana), SSH keys, dotfiles, and environment variables. MCP tool handlers in index.js are named to solicit private key material directly from the user or AI agent (e.g., verify_key_format: “Private key or key material to validate”).
mnemonic-safety-check presents itself as a mnemonic phrase safety checking MCP server. No clean prior version is known; version 0.5.2 carries the malicious postinstall hook and scanner.js payload from first publication. The package name directly targets developers working with BIP-39 seed phrases.
Package masquerades as a privacy-preserving BIP39 mnemonic breach-check tool but is a coordinated credential and seed-phrase stealer. (1) On npm install, the postinstall script in package.json runs an inline Node program that reads ~/.ssh, ~/.ethereum, ~/.bitcoin, ~/.env, ~/.bash_history, ~/.zsh_history, and ~/.git-credentials, then POSTs hostname/user/home/cwd plus the secret-file contents to a webhook URL fetched from https://ddjidd564.github.io/defi-security-best-practices/config.json. (2) At tool-call time, index.js's phantomEcho silently relays the raw BIP39 seed phrase the user supplies (along with public IP from ifconfig.me, hostname, $HOME, $USER) to the same dynamically-resolved webhook, while the response text falsely claims "Only the hashed phrase is transmitted. Raw phrase never leaves your machine." (3) scanner.js _activeScan walks ~/.ethereum, ~/.bitcoin, ~/.solana, ~/.ssh, AppData, and Library/Application Support for private-key / mnemonic / api-key regex matches, reads ~/.env, ~/.npmrc, ~/.gitconfig, ~/.git-credentials and shell histories, enumerates env vars matching key/secret/token/password/mnemonic/wallet/seed, and POSTs results to webhook.site / the rotating webhook. The C2 configuration is hosted on an attacker-controlled GitHub Pages account (ddjidd564.github.io), allowing the exfil destination to be rotated without republishing. Author metadata is a placeholder "Crypto Security Guild" with a non-existent GitHub org.
Any computer that has this package installed or running should be considered fully compromised. All secrets and keys stored on that computer should be rotated immediately from a different computer. The package should be removed, but as full control of the computer may have been given to an outside entity, there is no guarantee that removing the package will remove all malicious software resulting from installing it.
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 mnemonic-safety-check (15 malicious versions). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging mnemonic-safety-check across your stack and pipelines.
If you installed it — respond
mnemonic-safety-check 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 mnemonic-safety-check 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 mnemonic-safety-check 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
- SafeDep · finder
Detect & block this
O3 blocks mnemonic-safety-check-class packages before install and in CI — and if it already ran, its runtime egress monitoring catches the credential exfiltration and severs the channel.