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Malicious package

pfp-block-mobile-stepsnpm

pfp-block-mobile-steps is a confirmed malicious npm package (MAL-2026-12410) that steals credentials and exfiltrates sensitive data (malicious version 20.9.3). Do not install it — remove it immediately and rotate any exposed credentials.

Malicious code in pfp-block-mobile-steps (npm)

MAL-2026-12410
Immediate action
Remove the package, then rotate any secrets the build/runtime could reach.
npm uninstall pfp-block-mobile-steps

What this malware does

On require of the package, index.js unconditionally loads shim.js, which selects a payload path based on process.platform/arch (linux_x64, linux_arm64, darwin, win32) and downloads an opaque binary from one of four hardcoded Cloudflare Workers hosts (oob-worker.cf99-9b3.workers.dev, oob-worker.cf100-416.workers.dev, oob-worker.cf101-adf.workers.dev, oob-worker.cf102-baf.workers.dev). Endpoint hostnames are assembled at runtime from string fragments joined together to defeat static analysis. If HTTPS retrieval fails, a fallback path uses DNS TXT record lookups against *.dl.well1.site (reading a chunk count from c.<domain> then reassembling base64 payload from numbered TXT records) to deliver the same executable out-of-band. The fetched bytes are written to a temp path under a stealth filename (dotnet_diag.exe,.cache_), chmod 0755 on Unix, and spawned detached via /bin/sh -c or cmd /c start /b with stderr silenced. No hash or signature verification is performed, and no build/runtime purpose in a 'platform adapter' package requires this. A run-once flag file and opt-out environment variables gate re-execution, consistent with anti-analysis behavior.

Malicious versions

1 flagged
20.9.3

Indicators of compromise (SHA-256)

c4b4495333f6f37664594f2e6533842a4d3a317bb98bbc3a467797bb8ec851d7

Detection & response playbook

Credential / info stealer

  1. Find it

    Scan your lockfiles (package-lock.json, pnpm-lock.yaml, yarn.lock, requirements.txt, poetry.lock, etc.) and build artifacts for pfp-block-mobile-steps (version 20.9.3). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging pfp-block-mobile-steps across your stack and pipelines.

  2. If you installed it — respond

    pfp-block-mobile-steps 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.

  3. Did it already run?

    If pfp-block-mobile-steps 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.

  4. How O3 protects you

    O3 blocks pfp-block-mobile-steps 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. pfp-block-mobile-steps on npm has been identified as a malicious package (version 20.9.3 flagged). It should be removed immediately — do not install or keep it in your dependency tree.

Campaign

IN-MAL-2026-014635

References

Credits

  • Amazon Inspector · finder

Detect & block this

O3 blocks pfp-block-mobile-steps-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

Explore

All malware advisories How O3 detects malware Vulnerability database
pfp-block-mobile-steps (npm) malicious package — MAL-2026-12410 | O3 Security