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Malicious package

ac_semantic-ui_tsnpm

Advisory published Updated

ac_semantic-ui_ts is a confirmed malicious npm package (MAL-2026-5435) that steals credentials and exfiltrates sensitive data (malicious version 99.99.100). Do not install it — remove it immediately and rotate any exposed credentials.

Malicious code in ac_semantic-ui_ts (npm)

MAL-2026-5435
Immediate action
Remove the package, then rotate any secrets the build/runtime could reach.
npm uninstall ac_semantic-ui_ts

What this malware does

package.json declares a postinstall hook that runs canary.js, which issues an HTTP GET to bare IP 157.230.17.236 on port 80 with query parameters including os.hostname(), the package name and version, a nonce, and a lifecycle phase. The package name ac_semantic-ui_ts paired with the inflated version 99.99.100 is the canonical dependency-confusion shape — designed to win resolution over an internal/private registry entry of the same name. Any installer who resolves this package from public npm silently transmits their host identifier to an unencrypted, hardcoded, non-publisher endpoint with no opt-in. The README self-describes as an 'authorized benign dependency-confusion canary,' but the supply-chain mechanism — install-time exfiltration of installer host metadata to a third-party IP — is identical to a malicious dependency-confusion beacon, and any installer who pulls this unintentionally has their hostname leaked.

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.

Malicious versions

1 flagged
99.99.100

Indicators of compromise (SHA-256)

f8b97f7d3e69494d0415e13aec8d9d51ce1f5912d8c1de45a1e563e2d1b01d3d
0b851ebb2296d70685237abcc172029170d7c9e77e829c9a39d58188838e8db5

Detection & response playbook

Credential / info stealer
  1. Find it

    Search your lockfiles and build artifacts for ac_semantic-ui_ts (version 99.99.100).

  2. If you installed it — respond

    ac_semantic-ui_ts 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.

  3. Did it already run?

    If ac_semantic-ui_ts was installed, its post-install payload may already have run. Removing the package does not undo that — check outbound connections and credential use from the install window onward.

Frequently asked questions

No. ac_semantic-ui_ts on npm has been identified as a malicious package (version 99.99.100 flagged). It should be removed immediately — do not install or keep it in your dependency tree.

Campaign

IN-MAL-2026-005008GHSA-hjh8-hv66-6mwc

References

Credits

  • Amazon Inspector · finder

Detect & block this

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

Explore

ac_semantic-ui_ts (npm) malicious package — MAL-2026-5435 | O3 Security