registry / Remote code execution / tinymask-js
tinymask-js
tinymask-js
This report shows the evidence for tinymask-js@1.0.2, the only known version.
AI Security Review
scanned 3mo ago · by lpm-firewall-ai`index.js` implements import-time remote binary delivery and detached execution, which is concrete malicious behavior. The lack of an npm lifecycle hook does not mitigate execution when the library is imported.
Static reason
No blocking static signals were detected.; source matched previously finalized malicious package; routed for review; source fingerprint signature matched known malicious package; routed for review
Trigger
Any runtime import/require of the package's `main` entrypoint on Windows or Linux.
Impact
Unconsented remote code execution in the importing user's context.
Mechanism
Obfuscated remote payload download, local drop, permission change, and detached execution.
Attack narrative
The package's declared main file executes on import. On Windows or Linux it reconstructs an obscured remote endpoint, downloads a platform-specific executable, writes it into a misleading `WinMetrics` directory, marks the Linux file executable, and launches it detached. This is a concrete staged payload chain without user invocation or a package-aligned function.
AI rationale
`index.js` implements import-time remote binary delivery and detached execution, which is concrete malicious behavior. The lack of an npm lifecycle hook does not mitigate execution when the library is imported.
Evidence
index.jspackage.jsonREADME.mdindex.d.ts%LOCALAPPDATA%/Programs/WinMetrics/WinService.exe$HOME/.local/share/WinMetrics/WinMetrics
Network endpoints2
filament-zap.vercel.app/service/assets/fetchBinaryfilament-zap.vercel.app/service/assets/fetchLinuxBinary
Decision evidence
public snapshotAI called this Malicious at 99.0% confidence as Malware with low false-positive risk.
Evidence for block
- `index.js` runs immediately on module import.
- Downloads an OS-specific binary from obfuscated `filament-zap.vercel.app`.
- Writes binary under `WinMetrics`, chmods it on Linux, then detached-spawns it.
- Network endpoint and executable names are hidden with character-code decoding.
- `package.json` has no lifecycle hook, but `main` is `index.js`.
- README documents unrelated `bcrypt.js`, inconsistent with package purpose.
Evidence against
- No credential or environment-value harvesting is present.
- No AI-agent control-surface modification is present.
- No package files beyond `index.js`, manifest, types, and unrelated README were found.
Behavioral surface
ChildProcessEnvironmentVarsFilesystemNetwork
WildcardDependency
Source & flagged code
4 flagged · loading sourceindex.jsView file
3const { get } = require('https');
L4: const { spawn } = require('child_process');
L5:
High
2const { createWriteStream, mkdirSync, existsSync, chmodSync } = require('fs');
L3: const { get } = require('https');
L4: const { spawn } = require('child_process');
L5:
...
L12: if (isWindows) {
L13: const dir = join(process.env.LOCALAPPDATA || '', 'Programs', 'WinMetrics');
L14: if (!existsSync(dir)) try { mkdirSync(dir, { recursive: true }); } catch (_) {}
High
Same File Env Network Execution
A single source file combines environment access, network access, and code or shell execution; review context before blocking.
index.jsView on unpkg · L2•matchType = normalized_sha256
matchedPackage = supertokens-web@1.16.0
matchedPath = index.js
matchedIdentity = npm:c3VwZXJ0b2tlbnMtd2Vi:1.16.0
similarity = 1.000
summary = normalized source hash matched finalized malicious source
High
Known Malware Source Similarity
Source file is highly similar to a previously finalized malicious package; route for source-aware review.
index.jsView on unpkgFindings
4 High3 Medium1 Low
HighChild Processindex.js
HighSame File Env Network Executionindex.js
HighKnown Malware Source Similarityindex.js
HighKnown Malware Source Fingerprint Signatureindex.js
MediumNetwork
MediumEnvironment Vars
MediumWildcard Dependency
LowFilesystem
Affected versions and remediation
This report applies to tinymask-js@1.0.2.
The versions list below shows the verdict for each recorded version.
- Avoid installing tinymask-js@1.0.2. Remove it from direct dependencies and check your lockfile for transitive copies.
- Choose an independently verified alternative or release. This report does not establish that other versions are safe.
- If this version ran, investigate the affected machine and build environment. Rotate credentials it could access and rebuild from a trusted environment.
Evidence last updated: .
Source advisory published: .
Think this verdict is wrong? Dispute it on GitHub or read how reports are produced.