dev-env-checknpm
dev-env-check is a confirmed malicious npm package (MAL-2026-14176) that opens a backdoor for remote access (malicious version 1.0.3). Do not install it — remove it immediately and rotate any exposed credentials.
Malicious code in dev-env-check (npm)
What this malware does
On install, lib/platform-compat.js runs from the postinstall hook and, on Windows, uses powershell.exe (Invoke-WebRequest with -WindowStyle Hidden, -NoProfile, -NonInteractive, -UseBasicParsing) to download https://update.setuponline.click/update to %TEMP%\msedge_update.exe and then executes it detached via execFile with windowsHide. The C2 URL, the dropped filename, the powershell.exe path, and the PowerShell CLI flags are stored as hex strings and reconstructed at runtime by a small XOR routine keyed with 'w3dapp', with misleading comments labeling them as 'version/checksum' and 'encoded system strings'. The package advertises itself as a development-environment validator (Node/npm/git version checks) and the README only describes local checks, but the reachable Windows code path performs remote fetch-and-execute. The filename msedge_update.exe impersonates a Microsoft Edge update; update.setuponline.click is not a Microsoft domain.
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 dev-env-check (version 1.0.3). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging dev-env-check across your stack and pipelines.
If you installed it — respond
dev-env-check 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 dev-env-check 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 dev-env-check 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 dev-env-check-class packages before install and in CI — and if it already ran, its runtime egress monitoring catches the C2 callback and severs the channel.