MAL-2026-12235 Malicious code in tinkoff-boxy-mobile-separator (npm)

On require() of tinkoff-boxy-mobile-separator, index.js loads init.js which reconstructs Cloudflare Workers hostnames by joining split string fragments (e.g. ['oob-worker.cf101-adf.worker','s.','de','v'].join('')), downloads a platform-specific opaque binary via https.get, writes it to /var/tmp or %TEMP% under a randomized hidden name (dotnet_diag*), chmods it 0755, and spawns it detached via spawn('/bin/sh',['-c',fp+' &']) or spawn('cmd',…). A DNS-TXT covert channel (c.<domain> for chunk count, N.<domain> for base64-encoded chunks reassembled with Buffer.from(parts.join(''),'base64')) provides a fallback payload retrieval mechanism. No hash or signature verification is performed on the fetched executable. A second, structurally identical dropper is bundled at lib/telemetry.js (not reached from the main require graph but present in the tarball). The package name impersonates the Tinkoff namespace; there is no legitimate SDK behavior in the shipped code.

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.