js-crypto-promisenpm
js-crypto-promise is a confirmed malicious npm package (MAL-2026-5569) that typosquats a legitimate package to trick installs (malicious version 1.0.1). Do not install it — remove it immediately and rotate any exposed credentials.
Malicious code in js-crypto-promise (npm)
What this malware does
The package's prepinstall.js script base64-decodes a hidden URL (stored in a constant misleadingly named HASH_KEY decoding to https://jsonkeeper.com/b/DWNFF, an anonymous paste service), fetches the JSON body via axios, reads the .cache field, and pipes the contents into a detached node child process via stdin: const child = spawn('node', [], { detached: true, stdio: ['pipe', 'ignore', 'ignore'] }); child.stdin.write(k1);. This dropper fires automatically on npm install via scripts.postinstall. To defeat the --ignore-scripts mitigation, index.js also wraps a dynamic import('./prepinstall.js') inside a top-level IIFE, so any consumer that require('js-crypto-promise') re-triggers the same remote fetch and execution. The payload host is mutable, anonymous, unpinned, and unverified — the package author can swap in arbitrary code at any time. The package name impersonates the legitimate crypto-promise package: the README copies the real package's example code and embeds the real package's npm badge link, and the homepage points at the legitimate maintainer's GitHub repo. Installer impact: any npm install or require() of this package executes attacker-controlled Node.js code on the installer's machine.
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 js-crypto-promise (version 1.0.1). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging js-crypto-promise across your stack and pipelines.
If you installed it — respond
js-crypto-promise is a typosquat — you almost certainly intended a legitimately-named package. Remove js-crypto-promise, 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 js-crypto-promise 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 js-crypto-promise 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 js-crypto-promise-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.