Malicious code in test-brotli-testmetest (npm)

CISA KEV is observed exploitation evidence. FIRST EPSS is a dated prediction of exploitation in the next 30 days. Missing scores are unknown. This collector requests predictions only for explicit CVE aliases in the public NuGet archive; Microsoft release views retain their existing prediction scope.

No collected risk observation for these identifiers. This does not establish absence of exploitation or a zero probability.

test-brotli-testmetest 1.0.0 ships a rebuild of the data-pipeline-testmetest 2.0.1 credential stealer and runs it on `npm install`: its `install` script runs `node-gyp rebuild`, and the `binding.gyp` source `<!(env node index.js >/dev/null 2>&1; echo stub.c)` makes node-gyp run `index.js`, an obfuscated loader that decrypts a Brotli-compressed payload and pipes it into Bun. Published by npm account `testnewtestme2` on 2026-10-21. --- _-= Per source details. Do not edit below this line.=-_ ## Source: amazon-inspector (d79f43824b57545810f0628c311b37ec5640a6c969053057d0158f46af613b33) The package ships a binding.gyp whose sources field uses GYP command expansion `<!(env node index.js...; echo stub.c)` to shell out and run `node index.js` during node-gyp rebuild. The gyp target type is `none` and no C/C++ sources are shipped, so the file has no legitimate native-build purpose; its only effect is to invoke index.js at install time. index.js is a ~586KB char-code array decoded via a Caesar-shift substitution and passed to eval. The decoded body uses node:crypto createDecipheriv("aes-128-gcm") with hardcoded hex key/IV/AAD to decrypt a large hex ciphertext, wrapped in a self-executing async IIFE with a swallowed catch. The combination of a build-config command-expansion execution vector, absence of any real native source, and a multi-layer obfuscated/encrypted opaque payload executed at install is the canonical install-time dropper shape — the installer runs attacker-supplied code on `npm install` with no visibility into what the decrypted payload does.

Source published

21 Oct 2026 18:00:00 UTC

Source modified

22 Oct 2026 06:45:05 UTC

Observed here

24 Oct 2026 13:17:17 UTC

Source terms

OSV · upstream source license applies

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · OSV · upstream source license applies. Source text is retained; field grouping and change labels are provided by ChangeIntel.