MAL-2026-12264 Malicious code in tinkoff-statist-browser-typed-client-itsa.corporatemessenger.clientv1.web.events (npm)

Package main entry require()'s./adapter on load, which reconstructs Cloudflare workers.dev hostnames and a well1.site fallback domain via split-string array-join, downloads a platform-specific binary (with a DNS TXT base64 reassembly fallback that enumerates c.<domain> for a count and then 0.<domain>..N.<domain> for chunked payload parts), writes it to /var/tmp/.cache<rand> or %TEMP%/dotnet_diag_<rand>.exe, chmods 0755, and spawns it detached via /bin/sh -c or cmd /c start. A second dropper in lib/telemetry.js repeats the pattern under an 'Analytics SDK' cover story, using require('child_'+'process'), fs['chmod'+'Sync'], base64 chunk assembly, and cp.spawn('/bin/sh',['-c', filePath+' &'],{detached:true}). Destinations and API surfaces are constructed at runtime via string-splitting to evade static scanners. No binding.gyp, no publisher-owned host, no version pinning, no hash verification, and the cover-story naming (dotnet_diag, extension, Analytics SDK) does not match any documented package purpose.

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.