Which versions of uploader-frontend-legacy are malicious?

The following npm versions of uploader-frontend-legacy are flagged malicious: 9.9.11. Treat any of these as compromised.

How do I remediate uploader-frontend-legacy if I installed it?

uploader-frontend-legacy 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 uploader-frontend-legacy — how do I know if it already compromised me?

If uploader-frontend-legacy 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 uploader-frontend-legacy part of a known attack campaign?

Yes — uploader-frontend-legacy is associated with the IN-MAL-2026-014882 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 uploader-frontend-legacy 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 uploader-frontend-legacy (version 9.9.11). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging uploader-frontend-legacy across your stack and pipelines.

Malicious package

uploader-frontend-legacynpm

uploader-frontend-legacy is a confirmed malicious npm package (MAL-2026-12492) that opens a backdoor for remote access (malicious version 9.9.11). Do not install it — remove it immediately and rotate any exposed credentials.

Malicious code in uploader-frontend-legacy (npm)

MAL-2026-12492

Immediate action

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

npm uninstall uploader-frontend-legacy

What this malware does

The package's scripts.install runs node index.js, which loads lib/core.js and issues a dns.resolve4 query against a subdomain of oob.sl4x0.xyz constructed from os.userInfo().username, os.hostname(), and process.cwd(), along with a package tag and timestamp. Module names (os, dns, process), API names (userInfo, hostname, cwd, resolve4), and the destination domain oob.sl4x0.xyz are assembled from String.fromCharCode byte arrays in lib/b02e30.js, lib/6ad264.js, and lib/core.js to hide the behavior from casual review. The net effect on npm install is an outbound DNS beacon carrying installer-identifying data to an author-controlled out-of-band listener.

Malicious versions

1 flagged

9.9.11

Indicators of compromise (SHA-256)

0e90aa99bc8b8e4bb886e911c1fe5ffbddd1d7e730088105118db47170b66681

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 uploader-frontend-legacy (version 9.9.11). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging uploader-frontend-legacy across your stack and pipelines.
If you installed it — respond
uploader-frontend-legacy 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 uploader-frontend-legacy 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 uploader-frontend-legacy 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. uploader-frontend-legacy on npm has been identified as a malicious package (version 9.9.11 flagged). It should be removed immediately — do not install or keep it in your dependency tree.

Campaign

IN-MAL-2026-014882

References

npmjs.com

Credits

Amazon Inspector · finder

Detect & block this

O3 blocks uploader-frontend-legacy-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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