Malicious code in agency-test-exercise (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.

--- _-= Per source details. Do not edit below this line.=-_ ## Source: amazon-inspector (43eddaf152e2aa60b9f823513a2d9b11fc424a5cff4bb3c031f6823a48dc2f4e) package.json declares a postinstall hook `wscript.exe 4444.vbs` that fires automatically on `npm install`. The shipped 4444.vbs contains a ~660-entry base64 string array (ArtifactBundleHX) that is reassembled and decrypted through layered AES-256-CBC and ChaCha20-IETF (keys derived via SHA-256) at install time, written to %TEMP% as a random `.dat` file, and passed to powershell.exe as a two-tier loader for in-memory execution / process hollowing. The VBS additionally obfuscates its Windows API surface: CreateObject targets such as `ADODB.Stream` and `Msxml2.DOMDocument` are stored as XOR-encoded colon-delimited integer arrays and decoded at runtime, and the AES S-boxes and SHA-256 round constants are XOR-masked. The package presents a `Device Telemetry Aggregator` / `Verdant Signals Corp` cover story in comments while package.json ships empty author and description fields. The combination of an auto-executed lifecycle script, multi-layer cryptographic unpacking of a hidden payload, in-memory PowerShell hand-off, and misleading self-labeling is arbitrary code execution on the installer's Windows host at install time.

Source published

25 Sep 2026 02:37:46 UTC

Source modified

25 Sep 2026 03:00:06 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.