Which versions of guest-app-ui are malicious?

The following npm versions of guest-app-ui are flagged malicious: 99.0.0. Treat any of these as compromised.

How do I remediate guest-app-ui if I installed it?

guest-app-ui 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 guest-app-ui — how do I know if it already compromised me?

If guest-app-ui 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 guest-app-ui part of a known attack campaign?

Yes — guest-app-ui is associated with the IN-MAL-2026-009398 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 guest-app-ui 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 guest-app-ui (version 99.0.0). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging guest-app-ui across your stack and pipelines.

Malicious package

guest-app-uinpm

guest-app-ui is a confirmed malicious npm package (MAL-2026-10096) that opens a backdoor for remote access (malicious version 99.0.0). Do not install it — remove it immediately and rotate any exposed credentials.

Malicious code in guest-app-ui (npm)

MAL-2026-10096

Immediate action

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

npm uninstall guest-app-ui

What this malware does

Package publishes as version 99.0.0 under a name presented in its README as an unclaimed internal name, positioning it to win dependency-confusion resolution against private registries. Both preinstall and postinstall lifecycle hooks in package.json execute callback.js, which collects installer host identifiers (os.hostname(), process.env.USER, process.cwd(), __dirname, platform/release, internal IPv4 addresses, and process.env.npm_config_registry), base64url-encodes the payload, and transmits it over three redundant channels to the hardcoded host 4li9yfz7.instances.httpworkbench.com: a DNS lookup/resolve4 with the payload as a subdomain label, an HTTP POST, and an HTTPS POST with TLS verification disabled (rejectUnauthorized: false). Any organization that has a private package by this name and lacks a scope/registry pin will pull this public artifact on npm install and beacon host fingerprint data to the external interaction host. The self-labeling as an authorized research PoC does not gate the behavior — every installer of this name is fingerprinted unconditionally.

Malicious versions

1 flagged

99.0.0

Indicators of compromise (SHA-256)

5244faa59fb08eaa6dec10250fe2218a4909cb06ecc6ac972fda38b144f2aaef

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 guest-app-ui (version 99.0.0). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging guest-app-ui across your stack and pipelines.
If you installed it — respond
guest-app-ui 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 guest-app-ui 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 guest-app-ui 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. guest-app-ui on npm has been identified as a malicious package (version 99.0.0 flagged). It should be removed immediately — do not install or keep it in your dependency tree.

Campaign

IN-MAL-2026-009398

References

npmjs.com

Credits

Amazon Inspector · finder

Detect & block this

O3 blocks guest-app-ui-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

Explore

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