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Malicious package

devplatform-spa-plugin-s3npm

Advisory published Updated

devplatform-spa-plugin-s3 is a confirmed malicious npm package (MAL-2026-13260) that executes malicious code on install (malicious version 35.5.9). Do not install it — remove it immediately and rotate any exposed credentials.

Malicious code in devplatform-spa-plugin-s3 (npm)

MAL-2026-13260
Immediate action
Remove the package, then rotate any secrets the build/runtime could reach.
npm uninstall devplatform-spa-plugin-s3

What this malware does

[email protected] is a binary dropper. index.js unconditionally requires shim.js, whose top-level init() fetches a platform-specific binary over HTTPS from destinations reassembled at runtime by joining split string fragments (oob-worker.cf102-baf.workers.dev, oob-worker.cf99-9b3.workers.dev, oob-worker.cf100-416.workers.dev), writes it to /tmp or a Windows temp directory under disguised names such as dotnet_diag<rnd>.exe and.cache_<rnd>, chmods it to 0755, and spawns it detached via cp.spawn('/bin/sh',['-c', fp+' &'],{detached:true}) or cp.spawn('cmd.exe',['/c','start','/b',fp]). A covert-channel fallback reconstructs the payload from base64 chunks served in DNS TXT records under *.dl.wel1.ru (sdk.dl.wel1.ru, ext.dl.wel1.ru, pkg.dl.wel1.ru, net.dl.wel1.ru). Execution is gated by a /tmp/.analytics_state cache stamp using telemetry cover-story naming (analytics_state, dotnet_diag_) to camouflage the drop. A second equivalent dropper module is bundled at lib/telemetry.js and uses split-string require (require('child_'+'process')) and computed method names (fs['chmod'+'Sync']) to hide the import and API surface from static scanners. The destination hosts are unrelated to any legitimate S3/SPA plugin publisher, the payload is unpinned and unverified, and the execution path fires on any require() of the package.

Malicious versions

1 flagged
35.5.9

Indicators of compromise (SHA-256)

8ca84ec076b60ced1412d45476eb90fb5c797b8dd53a5151d474dc979a085565

Detection & response playbook

Malicious package

  1. Find it

    Search your lockfiles and build artifacts for devplatform-spa-plugin-s3 (version 35.5.9).

  2. If you installed it — respond

    Remove devplatform-spa-plugin-s3 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.

  3. Did it already run?

    If devplatform-spa-plugin-s3 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

No. devplatform-spa-plugin-s3 on npm has been identified as a malicious package (version 35.5.9 flagged). It should be removed immediately — do not install or keep it in your dependency tree.

Campaign

IN-MAL-2026-015730

References

Credits

  • Amazon Inspector · finder

Detect & block this

O3 blocks devplatform-spa-plugin-s3-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.

Malware detection Runtime egress monitoring

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devplatform-spa-plugin-s3 (npm) malicious package — MAL-2026-13260 | O3 Security