agency-test-exercisenpm
agency-test-exercise is a confirmed malicious npm package (MAL-2026-17170) that executes malicious code on install (malicious version 1.0.2). Do not install it — remove it immediately and rotate any exposed credentials.
Malicious code in agency-test-exercise (npm)
What this malware does
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.
Malicious versions
Indicators of compromise (SHA-256)
Detection & response playbook
Malicious packageFind it
Scan your lockfiles (package-lock.json, pnpm-lock.yaml, yarn.lock, requirements.txt, poetry.lock, etc.) and build artifacts for agency-test-exercise (version 1.0.2). O3 Security's supply-chain scanner checks every dependency against known-malicious package intelligence at install time and in CI, flagging agency-test-exercise across your stack and pipelines.
If you installed it — respond
Remove agency-test-exercise from your project and lockfile, then assume any secrets accessible to the build or runtime were exposed: rotate API keys, tokens, and credentials, and audit for unexpected outbound activity or persistence.
Did it already run?
If agency-test-exercise 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 agency-test-exercise 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
Campaign
References
Credits
- Amazon Inspector · finder
Detect & block this
O3 blocks agency-test-exercise-class packages before install and in CI — and if it already ran, its runtime egress monitoring catches the malicious outbound activity and severs the channel.