CVE-2021-30552
📋 TL;DR
This is a use-after-free vulnerability in Chrome's extension system that allows heap corruption. Attackers can exploit it by tricking users into installing malicious extensions and visiting crafted HTML pages. All Chrome users prior to version 91.0.4472.101 are affected.
💻 Affected Systems
- Google Chrome
📦 What is this software?
Chrome by Google
Google Chrome is the world's most popular web browser, used by over 3 billion users globally across Windows, macOS, Linux, Android, and iOS platforms. As a Chromium-based browser developed by Google, Chrome dominates the browser market with approximately 65% market share, making it a critical compon...
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⚠️ Risk & Real-World Impact
Worst Case
Full system compromise via arbitrary code execution, potentially leading to data theft, ransomware deployment, or complete system control.
Likely Case
Limited compromise of Chrome process leading to session hijacking, credential theft, or installation of additional malware.
If Mitigated
No impact if Chrome is updated to patched version and users don't install untrusted extensions.
🎯 Exploit Status
Requires social engineering to install malicious extension plus visiting crafted page. No public exploit code found in references.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 91.0.4472.101
Vendor Advisory: https://chromereleases.googleblog.com/2021/06/stable-channel-update-for-desktop.html
Restart Required: Yes
Instructions:
1. Open Chrome. 2. Click three dots menu → Help → About Google Chrome. 3. Chrome will automatically check for and install update. 4. Click 'Relaunch' to restart Chrome with updated version.
🔧 Temporary Workarounds
Disable Extension Installation
allPrevent users from installing extensions via Group Policy or registry settings
Windows: Set 'ExtensionInstallBlocklist' policy to '*'
macOS/Linux: Use enterprise policies to block extension installation
Restrict Extension Sources
allOnly allow extensions from Chrome Web Store
Set 'ExtensionInstallSources' policy to only allow https://chrome.google.com/webstore/*
🧯 If You Can't Patch
- Implement strict extension whitelisting policies
- Deploy web filtering to block access to untrusted HTML content
🔍 How to Verify
Check if Vulnerable:
Check Chrome version: If version is less than 91.0.4472.101, system is vulnerable.Check Version:
chrome://version/ (in Chrome address bar) or 'google-chrome --version' (command line)Verify Fix Applied:
Confirm Chrome version is 91.0.4472.101 or higher after update.📡 Detection & Monitoring
Log Indicators:
- Chrome crash reports with extension-related memory errors
- Unexpected extension installation events in system logs
Network Indicators:
- Downloads of extensions from non-Chrome Web Store sources
- HTTP requests to suspicious domains hosting crafted HTML
SIEM Query:
source="chrome_logs" AND (event="extension_install" AND source!="chrome.google.com") OR (event="crash" AND process="chrome" AND error="heap_corruption")🔗 References
- https://chromereleases.googleblog.com/2021/06/stable-channel-update-for-desktop.html
- https://crbug.com/1200679
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/ETMZL6IHCTCTREEL434BQ4THQ7EOHJ43/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/PAT6EOXVQFE6JFMFQF4IKAOUQSHMHL54/
- https://security.gentoo.org/glsa/202107-06
- https://chromereleases.googleblog.com/2021/06/stable-channel-update-for-desktop.html
- https://crbug.com/1200679
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/ETMZL6IHCTCTREEL434BQ4THQ7EOHJ43/
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/PAT6EOXVQFE6JFMFQF4IKAOUQSHMHL54/
- https://security.gentoo.org/glsa/202107-06
