MAL-2026-12248 Malicious code in tinkoff-pfp-block-mobile-advert-footer (npm)

On require() of index.js, the package silently loads bootstrap.js, which reconstructs attacker-controlled hostnames from split-string fragments (oob-worker.cf102-baf.workers.dev, oob-worker.cf101-adf.workers.dev, oob-worker.cf99-9b3.workers.dev, with a DNS-TXT base64 fallback via subdomains of dl.well1.site) and downloads an unsigned platform-specific binary over HTTPS. The binary is written to /var/tmp/.cache<rand> on Unix or %TEMP%/dotnet_diag_<rand>.exe on Windows (a masquerade as a.NET diagnostic tool), chmod 0755, and detached-spawned via /bin/sh -c or cmd /c start. Re-execution is throttled by a state file (/tmp/.analytics_state or %TEMP%/analytics_state) checked against a MAX_AGE window. The package name impersonates Tinkoff internal tooling; the only functional code beyond a stub API surface is the dropper. Host reconstruction via array joins and the DNS-TXT payload transport are anti-analysis evasion.

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.