Which versions of size-sensor are malicious?

The following npm versions of size-sensor are flagged malicious: 1.0.4, 1.1.4, 1.2.4. Treat any of these as compromised.

How do I remediate size-sensor if I installed it?

size-sensor 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 size-sensor — how do I know if it already compromised me?

If size-sensor 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 size-sensor part of a known attack campaign?

Yes — size-sensor is associated with the GHSA-gx6x-v325-85g4 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 size-sensor 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 size-sensor (3 malicious versions). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging size-sensor across your stack and pipelines.

Malicious package

size-sensornpm

Malicious code in size-sensor (npm) Remove it immediately and rotate any exposed credentials.

MAL-2026-4153

Immediate action

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

npm uninstall size-sensor

What this malware does

Part of the Mini Shai-Hulud supply chain attack campaign in which a threat actor compromised the npm account atool and published 631 malicious versions across 314 npm packages in an automated 22-minute burst. Each malicious version injects a preinstall hook that executes a 498KB obfuscated Bun script, using the GitHub API as a covert exfiltration channel. Credentials are committed to attacker-controlled repositories following Dune-themed naming patterns (e.g., harkonnen-melange-742). Stolen data includes AWS keys, GitHub PATs, npm tokens, GCP service accounts, Azure credentials, Kubernetes service account tokens, SSH keys, Docker auth configs, database connection strings, Stripe keys, and Slack tokens. Malicious versions also establish persistence via CI/CD workflow injection (a GitHub Actions workflow named Run Copilot dumps all secrets via toJSON(secrets)), AI agent session hooks, and a system daemon named kitty-monitor.

This specific package (size-sensor) was modified to include a malicious preinstall hook executing the obfuscated Bun payload.

The package size-sensor was found to contain malicious code.

Any computer that has this package installed or running should be considered fully compromised. All secrets and keys stored on that computer should be rotated immediately from a different computer. The package should be removed, but as full control of the computer may have been given to an outside entity, there is no guarantee that removing the package will remove all malicious software resulting from installing it.

This package was compromised as part of the ongoing "Mini Shai-Hulud is back" worm by the TeamPCP threat actor.

The package will steal credentials and then propogate it to every package it has access to. The package also attempts to remain persistent.

Malicious versions

3 flagged

1.0.41.1.41.2.4

Indicators of compromise (SHA-256)

847ef6b381d410bf176f7414a6f0fbbcf46a5f39b6d9011e126b279bd2d781df

474e08441943f7fd029411590aa970fc58597492c3d45a3c129383e6a3b04ad5

c713b7ced75cb3b92a66066a7061dbd2b4c69649408d54bf474e1ba4149d88a0

f766f53d38502ad0e1e9b606f40ae5943444e5888f124bbba73e63b30733bdec

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 size-sensor (3 malicious versions). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging size-sensor across your stack and pipelines.
If you installed it — respond
size-sensor 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 size-sensor 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 size-sensor 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. size-sensor on npm has been identified as a malicious package (versions 1.0.4, 1.1.4, 1.2.4 flagged). It should be removed immediately — do not install or keep it in your dependency tree.

Campaign

GHSA-gx6x-v325-85g4

References

Credits

Amazon Inspector · finder
SafeDep · finder

Detect & block this

O3 blocks size-sensor-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