Which versions of bigint.fs are malicious?

The following npm versions of bigint.fs are flagged malicious: 5.0.6. Treat any of these as compromised.

How do I remediate bigint.fs if I installed it?

bigint.fs establishes remote access, so treat any host that installed it as fully compromised. Isolate the machine, remove the package, rotate all credentials it could reach, and rebuild from a trusted image rather than cleaning in place — a backdoor may have planted additional persistence.

I already installed bigint.fs — how do I know if it already compromised me?

If bigint.fs 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 bigint.fs part of a known attack campaign?

Yes — bigint.fs is associated with the IN-MAL-2026-002659 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 bigint.fs 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 bigint.fs (version 5.0.6). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging bigint.fs across your stack and pipelines.

Malicious package

bigint.fsnpm

Malicious code in bigint.fs (npm) Remove it immediately and rotate any exposed credentials.

MAL-2026-3750

Immediate action

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

npm uninstall bigint.fs

What this malware does

On require()/import, index.js runs an IIFE that POSTs a getAccountInfo RPC call to https://api.devnet.solana.com for Solana account 4WF8QCFEnVD7BLs3QAVe2SjxRZ4n3EboCsdhj363VAqZ, base64-decodes the returned account data, reads a length prefix at offset 32, extracts the payload bytes at offset 36, and passes the resulting UTF-8 source to new Function('require','module','exports', src) — executing arbitrary JavaScript with the full privileges of the importing Node.js process. The payload is mutable (the attacker can rewrite the on-chain account data at any time), unpinned, not hash- or signature-verified, and delivered from infrastructure the attacker controls. The use of a public blockchain RPC endpoint as a C2 channel is designed to evade simple domain/IP blocking while remaining fully attacker-rewritable. The package name masquerades as a BigInt/filesystem utility; there is no legitimate reason for such a library to fetch and eval remote code on load.

Malicious versions

1 flagged

5.0.6

Indicators of compromise (SHA-256)

cb3e0cb5c95475ce69c3672be6acfb9283bc6e29a1d7ba7452c922e7dc96a966

Detection & response playbook

Backdoor / remote access

Find it
Scan your lockfiles (package-lock.json, pnpm-lock.yaml, yarn.lock, requirements.txt, poetry.lock, etc.) and build artifacts for bigint.fs (version 5.0.6). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging bigint.fs across your stack and pipelines.
If you installed it — respond
bigint.fs establishes remote access, so treat any host that installed it as fully compromised. Isolate the machine, remove the package, rotate all credentials it could reach, and rebuild from a trusted image rather than cleaning in place — a backdoor may have planted additional persistence.
Did it already run?
If bigint.fs 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 bigint.fs 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. bigint.fs on npm has been identified as a malicious package (version 5.0.6 flagged). It should be removed immediately — do not install or keep it in your dependency tree.

Campaign

IN-MAL-2026-002659

References

npmjs.com

Credits

Amazon Inspector · finder

Detect & block this

O3 blocks bigint.fs-class packages before install and in CI — and if it already ran, its runtime egress monitoring catches the C2 callback and severs the channel.

Malware detection Runtime egress monitoring