devplatform-spa-plugin-s3-feature-togglenpm
devplatform-spa-plugin-s3-feature-toggle is a confirmed malicious npm package (MAL-2026-12778) that executes malicious code on install (malicious version 35.7.1). Do not install it — remove it immediately and rotate any exposed credentials.
Malicious code in devplatform-spa-plugin-s3-feature-toggle (npm)
What this malware does
On require() of the package, index.js loads runtime.js which selects a platform-specific endpoint, downloads a binary over HTTPS from obfuscated Cloudflare Workers subdomains (oob-worker.cf103-070.workers.dev, oob-worker.cf102-baf.workers.dev, oob-worker.cf101-adf.workers.dev), writes it to /var/tmp/.cache<hex> on POSIX or %TEMP%\dotnet_diag_<hex>.exe on Windows, chmods 0755, and spawns it detached via /bin/sh -c or cmd. Destination hostnames are reconstructed by array-join to defeat static string scanning (e.g. ["oob-work","er.cf1","03-070.w","orke","rs",".d","ev"].join("")). When HTTPS delivery fails, _runtime.js falls back to a DNS-tunneled channel over TXT records at sdk.dl.wel1.ru / ext.dl.wel1.ru / pkg.dl.wel1.ru / net.dl.wel1.ru: it queries c.<domain> for a chunk count, iterates <i>.<domain> to retrieve base64-encoded chunks, concatenates and decodes them into a Buffer, writes the resulting binary to disk, chmods 0755, and spawns it. No hash or signature verification is performed; the payload is opaque and delivered from anonymous infrastructure; staging paths use hidden dot-file and dotnet_diag cover names; env-var opt-out gates (DISABLE_TELEMETRY, ANALYTICS_OPT_OUT, DO_NOT_TRACK) and analytics-themed comments frame the behavior as telemetry. The combination of import-time execution, obfuscated attacker-controlled hosts, DNS-TXT covert-channel fallback, and unverified native-binary execution gives full remote code execution on the installer's host on npm install / require().
Malicious versions
Indicators of compromise (SHA-256)
Detection & response playbook
Malicious packageFind it
Scan your lockfiles (package-lock.json, pnpm-lock.yaml, yarn.lock, requirements.txt, poetry.lock, etc.) and build artifacts for devplatform-spa-plugin-s3-feature-toggle (version 35.7.1). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging devplatform-spa-plugin-s3-feature-toggle across your stack and pipelines.
If you installed it — respond
Remove devplatform-spa-plugin-s3-feature-toggle 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.
Did it already run?
If devplatform-spa-plugin-s3-feature-toggle 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-spa-plugin-s3-feature-toggle 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 devplatform-spa-plugin-s3-feature-toggle-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.