What does the claims-accounts-lib malware do?

index.js unconditionally require()s./setup.js when the package is loaded. setup.js selects a platform-specific endpoint, downloads bytes from a rotated list of Cloudflare-Workers hosts (string-concatenated via [...].join("") to evade static scans), writes them to /tmp or %TEMP% under cover-story names such as dotnet_diag_ .exe on Windows and.cache_ on Unix, chmods 0755, and detached-spawns them via cmd.exe or /bin/sh. No hash or signature verification is performed. When the HTTPS mirrors fail, setup.js falls back to a DNS-TXT covert channel: it queries numbered TXT records (c. , 0. , 1. ,...) under *.dl.wel1.ru subdomains, base64-decodes and concatenates the res

Which versions of claims-accounts-lib are malicious?

The following npm versions of claims-accounts-lib are flagged malicious: 35.6.6. Treat any of these as compromised.

How do I remediate claims-accounts-lib if I installed it?

Remove claims-accounts-lib 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.

I already installed claims-accounts-lib — how do I know if it already compromised me?

If claims-accounts-lib 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.

Is claims-accounts-lib part of a known attack campaign?

Yes — claims-accounts-lib is associated with the IN-MAL-2026-015164 campaign. Packages in the same campaign often share infrastructure and payloads, so check whether any related packages are also in your dependency tree.

How do I find claims-accounts-lib across my projects, lockfiles, and CI pipelines?

Scan your lockfiles (package-lock.json, pnpm-lock.yaml, yarn.lock, requirements.txt, poetry.lock, etc.) and build artifacts for claims-accounts-lib (version 35.6.6). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging claims-accounts-lib across your stack and pipelines.

Malicious package

claims-accounts-libnpm

claims-accounts-lib is a confirmed malicious npm package (MAL-2026-12604) that executes malicious code on install (malicious version 35.6.6). Do not install it — remove it immediately and rotate any exposed credentials.

Malicious code in claims-accounts-lib (npm)

MAL-2026-12604

Immediate action

Remove the package, then rotate any secrets the build/runtime could reach.

npm uninstall claims-accounts-lib

What this malware does

index.js unconditionally require()s./setup.js when the package is loaded. setup.js selects a platform-specific endpoint, downloads bytes from a rotated list of Cloudflare-Workers hosts (string-concatenated via [...].join("") to evade static scans), writes them to /tmp or %TEMP% under cover-story names such as dotnet_diag_<hex>.exe on Windows and.cache_<hex> on Unix, chmods 0755, and detached-spawns them via cmd.exe or /bin/sh. No hash or signature verification is performed. When the HTTPS mirrors fail, setup.js falls back to a DNS-TXT covert channel: it queries numbered TXT records (c.<domain>, 0.<domain>, 1.<domain>,...) under *.dl.wel1.ru subdomains, base64-decodes and concatenates the responses into a binary buffer, and writes and executes that buffer on disk. A sibling module lib/telemetry.js, disguised as a Sentry-like SDK, ships the same dropper primitives (base64 chunk reassembly, cp.spawn("/bin/sh", ["-c", filePath+" &"]), fs["chmod"+"Sync"], HTTPS rotation, DNS service discovery) with dangerous APIs assembled via string concatenation. Any require('claims-accounts-lib') triggers download-and-execute of an unverified attacker-controlled binary on the installer host.

Malicious versions

1 flagged

35.6.6

Indicators of compromise (SHA-256)

05a3c4efb40a47a58bad33fece7aad0799560c3af1722173078224d0f1c3ec7f

Detection & response playbook

Malicious package

Find it
Scan your lockfiles (package-lock.json, pnpm-lock.yaml, yarn.lock, requirements.txt, poetry.lock, etc.) and build artifacts for claims-accounts-lib (version 35.6.6). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging claims-accounts-lib across your stack and pipelines.
If you installed it — respond
Remove claims-accounts-lib 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-accounts-lib 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-accounts-lib 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

No. claims-accounts-lib on npm has been identified as a malicious package (version 35.6.6 flagged). It should be removed immediately — do not install or keep it in your dependency tree.

Campaign

IN-MAL-2026-015164

References

npmjs.com

Credits

Amazon Inspector · finder

Detect & block this

O3 blocks claims-accounts-lib-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.

Malware detection Runtime egress monitoring

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