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 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.

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?

Search your lockfiles and build artifacts for uploader-frontend-legacy (version 9.9.11).

Malicious package

uploader-frontend-legacynpm

Advisory published Aug 5, 2026Updated Aug 5, 2026

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
Search your lockfiles and build artifacts for uploader-frontend-legacy (version 9.9.11).
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 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. 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

All malware advisories How O3 detects malware Vulnerability database