CVE-2021-30618
📋 TL;DR
CVE-2021-30618 is an inappropriate implementation vulnerability in Chromium's DevTools that could allow remote code execution. It affects Chromium-based browsers including Google Chrome and Microsoft Edge. Attackers could exploit this to execute arbitrary code on affected systems.
💻 Affected Systems
- Google Chrome
- Microsoft Edge
- Chromium-based browsers
📦 What is this software?
Edge by Microsoft
Edge Chromium by Microsoft
Fedora by Fedoraproject
⚠️ Risk & Real-World Impact
Worst Case
Remote attacker gains full control of the victim's system through arbitrary code execution, potentially leading to data theft, ransomware deployment, or system compromise.
Likely Case
Attackers exploit the vulnerability through malicious websites to execute code in the browser context, potentially stealing sensitive data or installing malware.
If Mitigated
With proper patching and security controls, the vulnerability is eliminated. Browser sandboxing may limit impact even if exploited.
🎯 Exploit Status
Exploitation requires user interaction (visiting malicious website) but no authentication. Technical details are limited in public disclosures.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Chrome 93.0.4577.63 and later, Edge 93.0.961.38 and later
Vendor Advisory: https://chromereleases.googleblog.com/2021/08/stable-channel-update-for-desktop_31.html
Restart Required: Yes
Instructions:
1. Open Chrome/Edge browser. 2. Click menu (three dots) → Help → About Google Chrome/About Microsoft Edge. 3. Browser will automatically check for and install updates. 4. Click 'Relaunch' to restart browser with updated version.
🔧 Temporary Workarounds
Disable DevTools
allPrevent access to DevTools which is required for exploitation
# For enterprise deployment via GPO/registry
# Set policy: DeveloperToolsAvailability = 2 (Disallowed)
Browser Sandbox Enforcement
allEnsure browser sandbox is properly configured and running
# Verify sandbox status on Linux: ps aux | grep -i chrome | grep -i sandbox
# Windows: Check Chrome properties for --no-sandbox flag
🧯 If You Can't Patch
- Restrict browser usage to essential personnel only
- Implement web filtering to block suspicious/malicious websites
- Use application whitelisting to prevent unauthorized code execution
- Enable enhanced security features like Chrome's Enhanced Protection mode
🔍 How to Verify
Check if Vulnerable:
Check browser version: Chrome/Edge → Menu → Help → About. If version is below 93.0.4577.63 (Chrome) or 93.0.961.38 (Edge), system is vulnerable.Check Version:
On Windows: "C:\Program Files\Google\Chrome\Application\chrome.exe" --version
On Linux: google-chrome --version
On macOS: /Applications/Google\ Chrome.app/Contents/MacOS/Google\ Chrome --versionVerify Fix Applied:
Confirm browser version is 93.0.4577.63 or higher for Chrome, 93.0.961.38 or higher for Edge. Test by attempting to reproduce exploitation scenarios.📡 Detection & Monitoring
Log Indicators:
- Unusual DevTools activity in browser logs
- Multiple crash reports from browser processes
- Suspicious JavaScript execution patterns
Network Indicators:
- Connections to known malicious domains from browser process
- Unusual outbound traffic patterns from browser
SIEM Query:
source="browser_logs" AND (event="devtools_access" OR event="browser_crash") AND version<"93.0.4577.63"🔗 References
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/IPJPUSAWIJMQFBQQQYXAICLI4EKFQOH6/
- https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-30618
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/IPJPUSAWIJMQFBQQQYXAICLI4EKFQOH6/
- https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-30618
