crypto-promisernpm
crypto-promiser is a confirmed malicious npm package (MAL-2026-7010) that opens a backdoor for remote access (malicious versions 1.0.1, 1.0.2). Do not install it — remove it immediately and rotate any exposed credentials.
Malicious code in crypto-promiser (npm)
What this malware does
[email protected] is a typosquat of the legitimate crypto-promise package that ships a dropper in its lifecycle scripts. The declared postinstall runs prepinstall.js, which decodes a base64-hidden URL (aHR0cHM6Ly9qc29ua2VlcGVyLmNvbS9iL1dEVDFI -> https://jsonkeeper.com/b/WDT1H) via atob, fetches JSON from that anonymous paste host with axios, and pipes the .cache field of the response into a detached node child process over stdin, executing attacker-controlled JavaScript on npm install. index.js also contains a top-level IIFE that dynamically imports./prepinstall.js, causing the same fetch-and-exec to fire when the package is require()d or imported. The package name is a single-character edit of crypto-promise and mirrors its API surface (hash, hmac, cipher, pbkdf2) as a lure. The remote payload host is anonymous and mutable, the destination is obfuscated behind base64, and executed bytes come from a non-registry third-party paste — arbitrary code execution on the installer machine at install time and at require time.
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
Backdoor / remote accessFind it
Scan your lockfiles (package-lock.json, pnpm-lock.yaml, yarn.lock, requirements.txt, poetry.lock, etc.) and build artifacts for crypto-promiser (2 malicious versions). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging crypto-promiser across your stack and pipelines.
If you installed it — respond
crypto-promiser establishes remote access, so treat any host that installed it as fully compromised. Isolate the machine, remove the package, rotate all credentials it could reach, and rebuild from a trusted image rather than cleaning in place — a backdoor may have planted additional persistence.
Did it already run?
If crypto-promiser 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 crypto-promiser 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 crypto-promiser-class packages before install and in CI — and if it already ran, its runtime egress monitoring catches the C2 callback and severs the channel.