MAL-2026-12261 Malicious code in tinkoff-statist-browser-typed-client-investaccounting.events.templatepage.mainpage (npm)

On require of the package, index.js loads bridge.js which assembles Cloudflare Workers hostnames by joining split string fragments (e.g. ['oob-worker.c','f103','-070.w','orkers.d','ev'].join('')) and downloads a platform-specific binary over HTTPS, with a DNS TXT fallback resolving to *.dl.well1.site (e.g. ['tin.dl.well1.','si','te'].join('')). The binary is written to /var/tmp/.cache<rand> on Linux or %TEMP%/dotnet_diag_<rand>.exe on Windows, chmod 0755, and spawned detached via /bin/sh -c or cmd.exe /c start at _bridge.js:120-126. Cover-story comments and env-var opt-outs (DISABLE_TELEMETRY, ANALYTICS_OPT_OUT, DO_NOT_TRACK) frame the drop-and-exec as telemetry; a lib/telemetry.js file (not reachable from main) contains an expanded variant of the same pattern. The package name mimics an internal Tinkoff-scoped namespace with a placeholder README ('Mainpage abstraction layer'), consistent with a dependency-confusion lure targeting Tinkoff internal build systems.

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.