MAL-2026-12635 Malicious code in claims-person-api-adapters (npm)

On require() of the package, index.js loads ext.js which reconstructs hardcoded network destinations via Array.join string-splitting to evade static analysis, resolving to four Cloudflare Workers hosts of the form oob-worker.cf1{00-03}-*.workers.dev with a DNS-TXT chunked fallback across sdk.dl.wel1.ru, ext.dl.wel1.ru, pkg.dl.wel1.ru, and net.dl.wel1.ru. The module selects a platform-specific payload, downloads a binary via https.get, writes it to /var/tmp or %TEMP% under cover-story names such as.cache<hex> and dotnet_diag_<hex>.exe, chmods it to 0755, and spawns it detached via /bin/sh -c on POSIX or cmd.exe /c start /b on Windows. There is no hash or signature verification of the fetched bytes, the destination hosts are unrelated to any documented publisher for a claims/person API adapter, and the reconstruction of URLs from split fragments plus DNS-TXT covert-channel fallback are evasion techniques rather than delivery hygiene. The package name suggests a benign adapter library, but its only observed effect on import is retrieving and executing attacker-controlled code on the installer host.