Which versions of arjson are malicious?

The following npm versions of arjson are flagged malicious: 0.1.4. Treat any of these as compromised.

How do I remediate arjson if I installed it?

arjson is built to steal secrets, so assume every credential the build or runtime could read is compromised. Remove it from your project and lockfile, then rotate ALL exposed secrets — npm/registry tokens, cloud keys, CI/CD secrets, SSH keys, and any .env values — from a known-clean machine. Audit logs for unauthorized use of those credentials.

I already installed arjson — how do I know if it already compromised me?

If arjson 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 arjson part of a known attack campaign?

Yes — arjson is associated with the IN-MAL-2026-006127 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 arjson 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 arjson (version 0.1.4). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging arjson across your stack and pipelines.

Malicious package

arjsonnpm

arjson is a confirmed malicious npm package (MAL-2026-5189) that steals credentials and exfiltrates sensitive data (malicious version 0.1.4). Do not install it — remove it immediately and rotate any exposed credentials.

Malicious code in arjson (npm)

MAL-2026-5189

Immediate action

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

npm uninstall arjson

What this malware does

package.json declares "preinstall": "./.github/scripts/precheck", which on npm install executes a 976KB UPX-packed Linux ELF binary shipped under .github/scripts/ (a path designed to look like CI tooling). The binary has no accompanying source, is compressed with UPX (http://upx.sf.net banner present in the packed image) to defeat static inspection, and its embedded strings reveal capabilities far beyond anything a JSON serialization library would require: libbpf/eBPF (LIBBPF_0.0), kernel tracing (PTRACE), netlink socket-diag enumeration (NETLINK_*_DIAG, INODE), HTTP client primitives (HTTP/1.1, POST, DELETE), GitHub API client (2022-11-28), Windows path handling (USERPROFILE), and asymmetric crypto (Ed25519, MLKEM, RSA_PKCS1_). Any developer or CI system running npm install arjson on Linux will execute opaque packed native code with kernel-level introspection and HTTP-exfiltration capability. The package is advertised as a JSON library; no legitimate purpose exists for shipping a packed eBPF/HTTP-capable preinstall binary.

This package was compromised as part of the IronWorm campaign. This campaign executes a malicious binary payload during installation via a preinstall hook. The payload is a Rust-built infostealer that targets developer environments, scanning for and harvesting credentials related to cloud providers, object storage, databases, source-control, package registries, and AI developer tools. It also targets cryptocurrency wallets, specifically injecting a malicious JavaScript hook into the Exodus desktop wallet to capture passwords and recovery phrases. Furthermore, the malware exhibits worm-like behavior by stealing GitHub and NPM credentials to push malicious updates to the victim's repositories and publish trojanized packages, and it uses an eBPF-based kernel rootkit to hide its processes and network connections on Linux systems.

Malicious versions

1 flagged

0.1.4

Indicators of compromise (SHA-256)

146faaf0d97c6a533a969bc3f3f117811f9317dc865ed4ab37f1679842ddeaae

00290c05e0c41a8f51d38c629ade5b3fe76f2a89302db8daac669b0c80d13197

Detection & response playbook

Credential / info stealer

Find it
Scan your lockfiles (package-lock.json, pnpm-lock.yaml, yarn.lock, requirements.txt, poetry.lock, etc.) and build artifacts for arjson (version 0.1.4). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging arjson across your stack and pipelines.
If you installed it — respond
arjson is built to steal secrets, so assume every credential the build or runtime could read is compromised. Remove it from your project and lockfile, then rotate ALL exposed secrets — npm/registry tokens, cloud keys, CI/CD secrets, SSH keys, and any .env values — from a known-clean machine. Audit logs for unauthorized use of those credentials.
Did it already run?
If arjson 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 arjson 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. arjson on npm has been identified as a malicious package (version 0.1.4 flagged). It should be removed immediately — do not install or keep it in your dependency tree.

Campaign

IN-MAL-2026-006127

References

Credits

Amazon Inspector · finder

Detect & block this

O3 blocks arjson-class packages before install and in CI — and if it already ran, its runtime egress monitoring catches the credential exfiltration and severs the channel.

Malware detection Runtime egress monitoring

Explore

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