50+ Malicious Chrome Extensions Bypass Store Security: 30K Users Infected with Adware HTML Injectors + Video

Introduction:

Cybercriminals recently distributed over 50 malicious Chrome extensions disguised as “live wallpaper” utilities, amassing around 30,000 victims through the Chrome Web Store and third‑party portals. These add‑ons abuse elevated browser permissions to inject remote HTML content, hijack browsing behavior, and bombard users with intrusive ads – transforming cosmetic tools into full‑fledged adware delivery systems.

Learning Objectives:

– Identify indicators of compromise (IoCs) for malicious Chrome extensions using browser forensic techniques.
– Execute manual and scripted removal of adware extensions across Windows and Linux environments.
– Implement proactive group policies and network controls to block unauthorised remote HTML injection.

You Should Know

1. Detecting Malicious Chrome Extensions via Local File System Forensics

Malicious extensions often persist outside the Chrome Web Store’s review process. On Windows, extension source files reside in `%LOCALAPPDATA%\Google\Chrome\User Data\Default\Extensions\`. On Linux, look under `~/.config/google-chrome/Default/Extensions/`. Each extension has a unique 32‑character ID folder. To list all installed extensions with their IDs and names:

Windows (PowerShell):

Get-ChildItem "$env:LOCALAPPDATA\Google\Chrome\User Data\Default\Extensions" -Directory | ForEach-Object {
$manifest = Join-Path $_.FullName "\manifest.json" | Resolve-Path -ErrorAction SilentlyContinue
if ($manifest) {
$json = Get-Content $manifest -Raw | ConvertFrom-Json
[bash]@{ ID = $_.Name; Name = $json.name; Version = $json.version }
}
}

Linux (Bash):

find ~/.config/google-chrome/Default/Extensions/ -1ame "manifest.json" -exec sh -c 'jq -r "\"\(.name) [\(.version)] : $(basename $(dirname $(dirname {})))\""' {} \;

Step‑by‑step guide:

1. Close all Chrome windows.

2. Navigate to the Extensions folder using the commands above.
3. Look for suspicious IDs – especially those with recent installation timestamps or obfuscated folder names.
4. Open each `manifest.json` and examine the `”permissions”` array for dangerous entries: `”webRequest”`, `”declarativeNetRequest”`, `”storage”`, `”tabs”`, `”http:///”`, `”https:///”`.
5. Cross‑reference the ID with known IoCs from reports (e.g., the 50+ extensions mentioned in the source: https://lnkd.in/gN9u5CDy).

2. Analysing Remote HTML Injection Behaviour Using Browser DevTools

These adware extensions load operator‑controlled HTML content into the current tab or new tabs. To catch them in action:

Step‑by‑step guide:

1. Open Chrome and press `F12` to launch DevTools.
2. Go to the Network tab and check “Preserve log”.

3. Clear existing logs and browse normally.

4. Look for requests originating from `chrome-extension:///` – these are local extension resources.
5. Pay attention to `fetch()` or `XMLHttpRequest` calls to external domains returning HTML blobs.
6. In the Elements tab, inspect the DOM for injected `