CVE-2021-30524
📋 TL;DR
This is a use-after-free vulnerability in Chrome's TabStrip component that allows heap corruption. Attackers can exploit it by convincing users to install a malicious extension and then visiting a crafted HTML page. Users of Chrome versions prior to 91.0.4472.77 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
Remote code execution leading to full system compromise, data theft, or installation of persistent malware.
Likely Case
Browser crash, memory corruption, or limited code execution within the browser sandbox.
If Mitigated
No impact if Chrome is updated to patched version or if malicious extensions are prevented from being installed.
🎯 Exploit Status
Exploitation requires social engineering to install malicious extension plus crafted HTML page. No public exploit code is known.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 91.0.4472.77 and later
Vendor Advisory: https://chromereleases.googleblog.com/2021/05/stable-channel-update-for-desktop_25.html
Restart Required: Yes
Instructions:
1. Open Chrome. 2. Click menu (three dots) > Help > About Google Chrome. 3. Chrome will automatically check for and install updates. 4. Click Relaunch to restart Chrome with the update.
🔧 Temporary Workarounds
Disable extension installation
allPrevent users from installing extensions to block the initial attack vector.
chrome://settings/extensions > Toggle 'Allow extensions from other stores' to OFF
Use Group Policy to restrict extension installation
Use Chrome Enterprise policies
allConfigure policies to block malicious extensions and restrict browser behavior.
Configure ExtensionInstallBlocklist and ExtensionInstallForcelist policies
🧯 If You Can't Patch
- Restrict extension installation permissions to trusted sources only.
- Implement web filtering to block access to potentially malicious HTML pages.
🔍 How to Verify
Check if Vulnerable:
Check Chrome version: If version is less than 91.0.4472.77, the system is vulnerable.Check Version:
On Chrome: chrome://version | On command line: google-chrome --versionVerify Fix Applied:
Confirm Chrome version is 91.0.4472.77 or higher after update.📡 Detection & Monitoring
Log Indicators:
- Chrome crash reports with TabStrip-related errors
- Unexpected extension installation events in system logs
Network Indicators:
- Requests to known malicious domains hosting crafted HTML pages
- Unusual extension update traffic
SIEM Query:
source="chrome_crash_reports" AND (message="TabStrip" OR message="use-after-free")🔗 References
- https://chromereleases.googleblog.com/2021/05/stable-channel-update-for-desktop_25.html
- https://crbug.com/1197146
- 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/2021/05/stable-channel-update-for-desktop_25.html
- https://crbug.com/1197146
- 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
