claims-create-client-validatornpm
claims-create-client-validator is a confirmed malicious npm package (MAL-2026-12612) that executes malicious code on install (malicious version 35.8.9). Do not install it — remove it immediately and rotate any exposed credentials.
Malicious code in claims-create-client-validator (npm)
What this malware does
On require('claims-create-client-validator'), index.js loads vendor.js whose top-level bootstrap() fetches an OS/arch-specific native binary over HTTPS from string-split-obfuscated hosts (oob-worker.cf99-9b3.workers.dev, oob-worker.cf101-adf.workers.dev, oob-worker.cf102-baf.workers.dev) with a DNS TXT fallback under *.dl.wel1.ru, writes it to /tmp/.cache<hex> on Unix or %TEMP%\dotnet_diag_<hex>.exe on Windows, chmods it 0o755, and spawns it detached via /bin/sh -c or cmd.exe. Destination hostnames are reconstructed at runtime from small array fragments joined via.join("") to evade string scanning. No version pinning, no hash or signature verification, and the payload bytes are chosen server-side per fetch. The dropper is skipped only when DISABLE_TELEMETRY, ANALYTICS_OPT_OUT, or DO_NOT_TRACK is set in the environment, and disguise filenames (dotnet_diag_,.cache_,.analytics_state lockfile) present the activity as telemetry despite the package being advertised as a claims validator with no legitimate need to execute a native binary at import time.
Malicious versions
Indicators of compromise (SHA-256)
Detection & response playbook
Malicious packageFind it
Scan your lockfiles (package-lock.json, pnpm-lock.yaml, yarn.lock, requirements.txt, poetry.lock, etc.) and build artifacts for claims-create-client-validator (version 35.8.9). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging claims-create-client-validator across your stack and pipelines.
If you installed it — respond
Remove claims-create-client-validator from your project and lockfile, then assume any secrets accessible to the build or runtime were exposed: rotate API keys, tokens, and credentials, and audit for unexpected outbound activity or persistence.
Did it already run?
If claims-create-client-validator was ever installed, its post-install/runtime payload may have already executed. O3's L7 egress monitoring and runtime eBPF sensors detect the credential exfiltration or command-and-control callback after install and block the malicious outbound channel, so you catch and contain the actual compromise — not just the presence of the package.
How O3 protects you
O3 blocks claims-create-client-validator before install through its supply-chain scanner, and if it has already run, detects and severs the exfiltration or C2 callback at runtime through L7 egress monitoring and eBPF.
Frequently asked questions
Campaign
References
Credits
- Amazon Inspector · finder
Detect & block this
O3 blocks claims-create-client-validator-class packages before install and in CI — and if it already ran, its runtime egress monitoring catches the malicious outbound activity and severs the channel.