type-atobnpm
Advisory published Updated
type-atob is a confirmed malicious npm package (MAL-2026-10174) that executes malicious code on install (malicious version 3.3.7). Do not install it — remove it immediately and rotate any exposed credentials.
Malicious code in type-atob (npm)
What this malware does
The package advertises itself as a pino-style logger (exports module.exports.pino = middleware, keywords fast/logger/stream/json, pino-like file layout under lib/) but its name and behavior are unrelated to logging. When the module is loaded via require(), its middleware factory spawns a detached node child process (spawn('node', [script,...], { detached: true, stdio: 'ignore' }), followed by child.unref()) running lib/caller.js. lib/caller.js fetches a JSON document from https://json.extendsclass.com/bin/49b93b00acf1 with https://jsonkeeper.com/b/XRGF3 as fallback, extracts the cookie field from the response, and executes it via new Function.constructor('require', s) with require passed in, granting the fetched code full Node module access. Additional endpoints are hidden as base64-encoded strings in a fake process stub inside lib/caller.js and lib/const.js (DEV_API_KEY decoding to https://jsonkeeper.com/b/XRGF3 and https://jsonkeeper.com/b/4NAKK). The remote content is attacker-mutable paste-style hosting, and the detached/unref/stdio-ignored spawn shape conceals the loader from the parent process.
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
Malicious packageFind it
Search your lockfiles and build artifacts for type-atob (version 3.3.7).
If you installed it — respond
Remove type-atob from your project and lockfile, then assume any secrets accessible to the build or runtime were exposed: rotate API keys, tokens, and credentials, and audit for unexpected outbound activity or persistence.
Did it already run?
If type-atob was installed, its post-install payload may already have run. Removing the package does not undo that — check outbound connections and credential use from the install window onward.
Frequently asked questions
Campaign
References
Credits
- Amazon Inspector · finder
Detect & block this
O3 blocks type-atob-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.