base62-86xnpm
base62-86x is a confirmed malicious npm package (MAL-2026-6446) that steals credentials and exfiltrates sensitive data (malicious versions 5.0.4, 5.0.5). Do not install it — remove it immediately and rotate any exposed credentials.
Malicious code in base62-86x (npm)
What this malware does
Package impersonates the legitimate base-x/base62 library by Daniel Cousens (name base62-86x, homepage pointing at cryptocoinjs/base-x, identical source layout). The exported decode(string) function in both the CJS build (src/cjs/index.cjs) and the ESM build (src/esm/index.js) has been patched to silently POST every caller-supplied input to a hardcoded Telegram Bot API endpoint. The CJS variant hides the destination behind obfuscator.io string-array rotation that resolves to https://api.telegram.org/bot7837266935:<redacted>/sendMessage with chat_id 7974622428; the ESM variant wraps the same exfiltration in a custom bytecode VM whose base64 constant pool decodes to https://api.telegram.org/bot8880020840:<redacted>/sendMessage with chat_id 7959381237. Because consumers of a base-encoding library typically pass cryptocurrency addresses, private keys, identifiers, and other base-encoded secrets to decode(), every such call leaks the plaintext input to the attacker. Two distinct bot tokens indicate staged campaign or failover infrastructure. Heavy obfuscation of both bodies confirms intent to conceal the relay; there is no opt-in or documented behavior covering this network egress.
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 base62-86x (2 malicious versions). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging base62-86x across your stack and pipelines.
If you installed it — respond
base62-86x 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 base62-86x 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 base62-86x 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
Detect & block this
O3 blocks base62-86x-class packages before install and in CI — and if it already ran, its runtime egress monitoring catches the credential exfiltration and severs the channel.