CVE-2021-37980: Google Chrome Sandbox Bypass Vulnerability

CVE-2021-37980 Overview

CVE-2021-37980 is an inappropriate implementation vulnerability in the Sandbox component of Google Chrome prior to version 94.0.4606.81. This security flaw allows a remote attacker to potentially bypass site isolation protections via Windows-specific attack vectors. Site isolation is a critical security boundary in Chrome that ensures web content from different sites is rendered in separate processes, preventing cross-site data leakage.

Critical Impact

Successful exploitation allows attackers to bypass Chrome's site isolation security model, potentially enabling cross-site information disclosure and undermining a fundamental browser security mechanism designed to protect sensitive user data.

Affected Products

• Google Chrome (versions prior to 94.0.4606.81)
• Microsoft Windows (when running vulnerable Chrome versions)
• Fedora 33 (with vulnerable Chrome packages)
• Debian Linux 10.0 and 11.0 (with vulnerable Chrome/Chromium packages)

Discovery Timeline

• 2021-11-02 - CVE-2021-37980 published to NVD
• 2024-11-21 - Last updated in NVD database

Technical Details for CVE-2021-37980

Vulnerability Analysis

The vulnerability resides in Google Chrome's Sandbox implementation, specifically affecting how the browser enforces site isolation on Windows platforms. Site isolation is designed to render content from different websites in separate processes, creating a security boundary that prevents malicious sites from accessing data from other sites the user may be logged into.

The inappropriate implementation in the Sandbox allows attackers to circumvent these isolation boundaries. When successfully exploited, an attacker can potentially access cross-origin data that should be protected by Chrome's security architecture. The attack requires user interaction, as the victim must navigate to a malicious website or interact with attacker-controlled content.

This vulnerability is particularly concerning because it undermines one of Chrome's core security defenses against Spectre-class side-channel attacks and traditional cross-site data theft attempts.

Root Cause

The root cause stems from an inappropriate implementation within Chrome's Sandbox component on Windows. The Sandbox is responsible for enforcing process isolation and restricting the capabilities of renderer processes. The specific implementation flaw allows certain operations or data to escape the intended isolation boundaries, enabling cross-site information access that should be prevented by the sandbox's security policies.

Attack Vector

The attack is network-based and requires user interaction. An attacker would need to:

1. Host malicious content on an attacker-controlled website
2. Lure the victim to visit the malicious site while also having sensitive sites open
3. Exploit the sandbox implementation flaw to bypass site isolation
4. Access cross-origin data from other sites the victim is authenticated to

The vulnerability specifically affects Chrome on Windows, suggesting the issue relates to Windows-specific sandbox implementation details or interactions with the Windows operating system.

The exploitation mechanism involves leveraging the inappropriate sandbox implementation to read cross-origin data. For detailed technical information, refer to the Chromium Bug Report #1254631 and the Google Chrome Stable Update announcement.

Detection Methods for CVE-2021-37980

Indicators of Compromise

• Monitor for Chrome processes exhibiting unusual cross-process memory access patterns
• Check for browser crashes or unexpected behavior following visits to suspicious websites
• Review browser version information to identify unpatched installations running versions below 94.0.4606.81

Detection Strategies

• Implement endpoint monitoring to detect Chrome versions prior to 94.0.4606.81 across the organization
• Deploy network-based detection for known malicious domains that may attempt to exploit sandbox bypass vulnerabilities
• Utilize browser telemetry to identify unusual renderer process behavior indicative of site isolation bypass attempts

Monitoring Recommendations

• Enable Chrome's built-in security reporting features to capture sandbox-related anomalies
• Monitor system logs for unexpected Chrome process behavior on Windows endpoints
• Implement SentinelOne Singularity platform to detect and respond to browser-based exploitation attempts in real-time

How to Mitigate CVE-2021-37980

Immediate Actions Required

• Update Google Chrome to version 94.0.4606.81 or later immediately on all Windows systems
• Enable automatic updates for Chrome to ensure timely patching of future vulnerabilities
• Review and update Chromium-based browsers on Debian and Fedora systems using vendor-provided security updates
• Implement network segmentation to limit potential impact if exploitation occurs

Patch Information

Google has addressed this vulnerability in Chrome version 94.0.4606.81. Organizations should update to this version or later immediately. The fix is documented in the Google Chrome Stable Channel Update.

For Linux distributions:

• Debian users should apply DSA-5046
• Fedora 33 users should apply updates from the Fedora Package Announcement

Workarounds

• Consider using alternative browsers on Windows systems until Chrome can be updated
• Implement strict Content Security Policy headers on sensitive web applications to add defense-in-depth
• Limit access to untrusted websites through web filtering solutions while awaiting patch deployment
• Use browser isolation technologies to contain potential exploitation attempts

# Verify Chrome version on Windows (PowerShell)
(Get-Item "C:\Program Files\Google\Chrome\Application\chrome.exe").VersionInfo.FileVersion

# Force Chrome update check via command line
"C:\Program Files\Google\Chrome\Application\chrome.exe" --check-for-update-interval=1