What does the devplatform-select-user malware do?

On require(), the package loads _bridge.js which downloads a platform-specific binary over HTTPS from hardcoded Cloudflare Workers mirrors (oob-worker.cf99-9b3.workers.dev, cf101-adf.workers.dev, cf102-baf.workers.dev), writes it to /var/tmp or %TEMP% under cover-story names such as.cache_ and dotnet_diag_ .exe, chmods it 0755, and spawns it detached via cp.spawn('/bin/sh', ['-c', fp+' &']) on POSIX or cmd on Windows. Destination hostnames are reconstructed at runtime from split character arrays (['oob-worker.cf99-9b3.worke','rs.','de','v'].join('')) to evade string-based scanners. A DNS fallback channel resolves TXT records under *.dl.wel1.ru (assembled the same way in _DNS_MAP) to

Which versions of devplatform-select-user are malicious?

The following npm versions of devplatform-select-user are flagged malicious: 35.4.4. Treat any of these as compromised.

How do I remediate devplatform-select-user if I installed it?

devplatform-select-user is built to steal secrets, so assume every credential the build or runtime could read is compromised. Remove it from your project and lockfile, then rotate ALL exposed secrets — npm/registry tokens, cloud keys, CI/CD secrets, SSH keys, and any .env values — from a known-clean machine. Audit logs for unauthorized use of those credentials.

I already installed devplatform-select-user — how do I know if it already compromised me?

If devplatform-select-user 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.

Is devplatform-select-user part of a known attack campaign?

Yes — devplatform-select-user is associated with the IN-MAL-2026-015026 campaign. Packages in the same campaign often share infrastructure and payloads, so check whether any related packages are also in your dependency tree.

How do I find devplatform-select-user across my projects, lockfiles, and CI pipelines?

Scan your lockfiles (package-lock.json, pnpm-lock.yaml, yarn.lock, requirements.txt, poetry.lock, etc.) and build artifacts for devplatform-select-user (version 35.4.4). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging devplatform-select-user across your stack and pipelines.

Malicious package

devplatform-select-usernpm

devplatform-select-user is a confirmed malicious npm package (MAL-2026-12752) that steals credentials and exfiltrates sensitive data (malicious version 35.4.4). Do not install it — remove it immediately and rotate any exposed credentials.

Malicious code in devplatform-select-user (npm)

MAL-2026-12752

Immediate action

Remove the package, then rotate any secrets the build/runtime could reach.

npm uninstall devplatform-select-user

What this malware does

On require(), the package loads bridge.js which downloads a platform-specific binary over HTTPS from hardcoded Cloudflare Workers mirrors (oob-worker.cf99-9b3.workers.dev, cf101-adf.workers.dev, cf102-baf.workers.dev), writes it to /var/tmp or %TEMP% under cover-story names such as.cache<hex> and dotnet_diag_<hex>.exe, chmods it 0755, and spawns it detached via cp.spawn('/bin/sh', ['-c', fp+' &']) on POSIX or cmd on Windows. Destination hostnames are reconstructed at runtime from split character arrays (['oob-worker.cf99-9b3.worke','rs.','de','v'].join('')) to evade string-based scanners. A DNS fallback channel resolves TXT records under *.dl.wel1.ru (assembled the same way in _DNS_MAP) to retrieve or exfiltrate chunked data when HTTPS is blocked. The package's advertised purpose is a 'select user' UI helper — there is no functional reason for it to fetch and execute an opaque native binary from anonymous Cloudflare Workers subdomains at import time. Cover-story comments ('Shuffle endpoints to distribute load', 'Clean up temporary files') and a DISABLE_TELEMETRY opt-out gate frame the dropper as diagnostics. Installing or importing this package results in attacker-controlled code executing on the host.

Malicious versions

1 flagged

35.4.4

Indicators of compromise (SHA-256)

e2f7e22a3a99d2447b8bc3e6c0b1f4a92077ce570fdacff421e9fdee6a83e723

Detection & response playbook

Credential / info stealer

Find it
Scan your lockfiles (package-lock.json, pnpm-lock.yaml, yarn.lock, requirements.txt, poetry.lock, etc.) and build artifacts for devplatform-select-user (version 35.4.4). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging devplatform-select-user across your stack and pipelines.
If you installed it — respond
devplatform-select-user is built to steal secrets, so assume every credential the build or runtime could read is compromised. Remove it from your project and lockfile, then rotate ALL exposed secrets — npm/registry tokens, cloud keys, CI/CD secrets, SSH keys, and any .env values — from a known-clean machine. Audit logs for unauthorized use of those credentials.
Did it already run?
If devplatform-select-user 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 devplatform-select-user 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

No. devplatform-select-user on npm has been identified as a malicious package (version 35.4.4 flagged). It should be removed immediately — do not install or keep it in your dependency tree.

Campaign

IN-MAL-2026-015026

References

npmjs.com

Credits

Amazon Inspector · finder

Detect & block this

O3 blocks devplatform-select-user-class packages before install and in CI — and if it already ran, its runtime egress monitoring catches the credential exfiltration and severs the channel.

Malware detection Runtime egress monitoring

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