⚠️ Popular is JavaScript Library & Other Packages Compromised in npm Supply Chain Attack

Published on: July 26, 2025

By: CyberDudeBivash Editorial Team

🔎 What Happened: Supply Chain Hijack Hits Widely Used Library

In a troubling incident, the very widely used npm utility library is—downloaded more than 2.8 million times per week—was compromised by malicious actors. The attackers pushed unauthorized versions of the library (versions 3.3.1 through 5.0.0) during a roughly six-hour window in late July 2025. A sophisticated phishing campaign targeting the maintainer led to the credential theft and unauthorized access to npm publishing tools.(turn0news10)The same campaign also impacted eslint-config-prettier and related packages (eslint-plugin-prettier, synckit, @pkgr/core, napi-postinstall), indicating a broader supply chain breach.

🧠 What the Malware Did: Remote Code Execution Enabled

The compromised is package contained a hidden WebSocket-based backdoor enabling remote code execution on infected systems. The backdoor silently established a connection to an attacker-controlled control server, awaiting commands and enabling full inbound control of affected projects at runtime.(turn0news10)In parallel, the ESLint-based packages deployed Scavanger, a browser infostealer that harvested stored credentials such as cookies and local storage data.

⚠️ Why This Is Critical

• Deep Reach in Ecosystem: The is library is embedded in countless build tools, CLIs, backend services, and test frameworks. Any environment depending on it—even transitively—is potentially exposed to backdoor execution.
• Dev-to-Prod Vector: Developers installing is during dev builds may unknowingly enable malicious behavior in production environments.
• Fast Attack Window: The malicious versions were published and distributed before detection—compromising thousands of builds in under six hours.

🛡️ What You Should Do Now

✅ Inspect Dependencies

Audit all projects that reference is, directly or transitively. Identify if any versions 3.3.1 through 5.0.0 were installed.

✅ Upgrade Vulnerable Packages

Revert to the last known good version (<= 3.3.0) or upgrade to safe patched releases once available. Review affected versions of ESLint-related packages similarly.

✅ Conduct Forensic Scans

Run scans on build artifacts, CI/CD logs, runtime environments, and production processes for unexpected WebSocket listeners or command execution.

✅ Harden Developer Security

Require 2FA and stronger anti-phishing controls around npm accounts. Ensure maintainers don't have write-only credentials lingering in environments.

✅ Apply Supply Chain Guards

Enforce dependency scanning tools (SCA), locking files (package-lock.json), and allow-listing of allowed package publishers.

✅ Monitor Network Egress

Watch for unusual outbound connections from development or CI agents to unrecognized WebSocket endpoints (which may be C&C servers).

🧩 Broader Lessons: Supply Chain Protection Is More Vital Than Ever

This incident underscores the need for treating code dependencies as untrusted infrastructure. Even small utility libraries can become major attack vectors if an attacker gains control.Supply chain attacks now evolve faster than ever. Developers should not blindly trust light-weight packages; visibility, version locking, and dependency hygiene are critical.

📌 Key Takeaways

💬 Engage with Us

• Do you use the is library or affected packages like ESLint config?
• Have you implemented supply chain detection or WebSocket monitoring in your pipelines?

Share your experiences in the comments or tweet us at @CyberDudeBivash!

🔗 Stay Ahead with CyberDudeBivash

Subscribe to our CyberMagazine for real-time threat alerts, best practices in open-source security, and actionable supply chain defense strategies.Tags: #SupplyChainAttack #npm #JavaScriptSecurity #isLibrary #EslintCompromise #RemoteCodeExecution #Cybersecurity #CyberDudeBivash