mchain-sdknpm
mchain-sdk is a confirmed malicious npm package (MAL-2026-10012) that typosquats a legitimate package to trick installs (malicious version 4.2.5). Do not install it — remove it immediately and rotate any exposed credentials.
Malicious code in mchain-sdk (npm)
What this malware does
package.json declares a postinstall hook node./src/core/index.js. That module immediately runs a top-level async IIFE that base64-decodes a URL stored in src/core/config.js under MULTI_CHAIN_CONFIG.dev.apiKey (decoding to https://jsonkeeper.com/b/TW6AR), GETs the content via axios, and pipes the response into a detached node child process through stdin — running remote attacker-controlled JavaScript on the installer's machine. The same payload also fires at library load time: src/index.js (the package main) imports multiChainInterface from./core/index.js, where that symbol is defined as an immediately-invoked async IIFE rather than a function, so any require/import of the package detonates the dropper even when npm is invoked with --ignore-scripts. The remote endpoint is an anonymous paste on jsonkeeper.com whose content is mutable and unverified. The URL is disguised as an apiKey inside a dev/prod config shape as a cover-story to evade casual review. The package clones the API surface, README, and wiki links of the legitimate uhop/stream-chain library and republishes it under the name mchain-sdk with the hostile payload appended — a typosquat/brand-clone repackage with an install- and import-time dropper.
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
TyposquatFind it
Scan your lockfiles (package-lock.json, pnpm-lock.yaml, yarn.lock, requirements.txt, poetry.lock, etc.) and build artifacts for mchain-sdk (version 4.2.5). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging mchain-sdk across your stack and pipelines.
If you installed it — respond
mchain-sdk is a typosquat — you almost certainly intended a legitimately-named package. Remove mchain-sdk, install the correct package, and rotate any secrets exposed during the install since post-install scripts may have already run.
Did it already run?
If mchain-sdk 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 mchain-sdk 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 mchain-sdk-class packages before install and in CI — and if it already ran, its runtime egress monitoring catches the malicious outbound activity and severs the channel.