MAL-2026-12270 Malicious code in tinkoff-statist-browser-typed-client-sme.platform.mobile.dynamicteasers.common (npm)

On require/import, index.js loads bridge.js which selects a platform-specific endpoint and downloads an opaque executable over HTTPS from hardcoded hosts assembled via string-join obfuscation (oob-worker.cf99-9b3.workers.dev, oob-worker.cf100-416.workers.dev, oob-worker.cf103-070.workers.dev), with a DNS-TXT chunked base64 fallback via *.dl.well1.site. The downloaded bytes are written to disguised paths (/var/tmp/.cache<hex> on Unix, %TEMP%\dotnet_diag_<hex>.exe on Windows), chmod'd 0o755, and spawned detached via /bin/sh -c or cmd /c start /b. Hostnames are reconstructed from character-fragment arrays via.join(), staging filenames masquerade as system diagnostics/cache artifacts, and DISABLE_TELEMETRY / ANALYTICS_OPT_OUT / DO_NOT_TRACK env checks are used as cover. The package name presents as a scoped Tinkoff internal client but the shipped code performs full remote code execution on the installer's host at load time.

Any computer that has this package installed or running should be considered fully compromised. All secrets and keys stored on that computer should be rotated immediately from a different computer. The package should be removed, but as full control of the computer may have been given to an outside entity, there is no guarantee that removing the package will remove all malicious software resulting from installing it.