CVE-2020-16044: Google Chrome Use-After-Free Vulnerability

CVE-2020-16044 Overview

CVE-2020-16044 is a use after free vulnerability in the WebRTC component of Google Chrome prior to version 88.0.4324.96. This memory corruption flaw allows a remote attacker to potentially exploit heap corruption via a crafted SCTP (Stream Control Transmission Protocol) packet. The vulnerability exists due to improper memory management in the WebRTC implementation, where memory is accessed after it has been freed.

Critical Impact

Remote attackers can exploit this vulnerability to achieve heap corruption through specially crafted SCTP packets, potentially leading to arbitrary code execution within the browser context. User interaction is required as the victim must visit a malicious webpage.

Affected Products

• Google Chrome versions prior to 88.0.4324.96

Discovery Timeline

• 2021-01-19 - Google releases security patch in Chrome 88.0.4324.96
• 2021-02-09 - CVE-2020-16044 published to NVD
• 2024-11-21 - Last updated in NVD database

Technical Details for CVE-2020-16044

Vulnerability Analysis

This vulnerability is classified as CWE-416 (Use After Free), a memory corruption issue that occurs when a program continues to use a pointer after it has been freed. In the context of Google Chrome's WebRTC implementation, the flaw resides in the handling of SCTP packets. WebRTC (Web Real-Time Communication) is a browser technology that enables peer-to-peer communication for audio, video, and data sharing. SCTP is used within WebRTC for reliable data channel communication.

The vulnerability allows an attacker to trigger a condition where freed memory is subsequently accessed, leading to heap corruption. This type of vulnerability is particularly dangerous because it can be leveraged to achieve arbitrary code execution by manipulating heap memory layout.

Root Cause

The root cause of CVE-2020-16044 lies in improper memory lifecycle management within Chrome's WebRTC SCTP implementation. When processing certain SCTP packets, the browser fails to properly track memory allocation and deallocation, resulting in a dangling pointer scenario. When this freed memory is later accessed during packet processing, it can lead to use of attacker-controlled data that may have been reallocated to the same memory location.

Attack Vector

The attack vector for this vulnerability is network-based, requiring user interaction. An attacker can exploit this vulnerability by:

1. Hosting a malicious webpage that initiates a WebRTC connection
2. Sending specially crafted SCTP packets through the WebRTC data channel
3. Triggering the use after free condition through specific packet sequences
4. Exploiting the heap corruption to potentially execute arbitrary code

The attacker can craft malicious SCTP packets designed to trigger the vulnerable code path in Chrome's WebRTC implementation. When a user visits a webpage controlled by the attacker, the malicious JavaScript can establish a WebRTC connection and deliver the exploit payload through SCTP data channels. For detailed technical information, refer to Chromium Bug Report #1163228.

Detection Methods for CVE-2020-16044

Indicators of Compromise

• Unexpected WebRTC connections initiated from browser sessions to unknown or suspicious peers
• Browser crashes or abnormal memory consumption during WebRTC sessions
• Anomalous SCTP traffic patterns or malformed SCTP packets in network logs
• Unusual JavaScript execution or WebRTC API calls from untrusted websites

Detection Strategies

• Monitor for Chrome browser crashes with heap corruption signatures in crash dumps
• Implement network-based detection for malformed or suspicious SCTP packets within WebRTC connections
• Deploy endpoint detection solutions capable of identifying use after free exploitation attempts
• Review browser process memory for signs of heap spray or memory manipulation techniques

Monitoring Recommendations

• Enable Chrome crash reporting and monitor for patterns consistent with memory corruption exploits
• Implement network traffic analysis for WebRTC connections to detect anomalous SCTP behavior
• Deploy SentinelOne endpoint protection with behavioral AI to detect exploitation attempts in real-time
• Maintain browser version inventory to identify systems running vulnerable Chrome versions

How to Mitigate CVE-2020-16044

Immediate Actions Required

• Update Google Chrome to version 88.0.4324.96 or later immediately
• Enable automatic updates for Chrome browsers across the organization
• Audit all systems to identify instances of vulnerable Chrome versions
• Consider restricting WebRTC functionality via enterprise policies until patching is complete

Patch Information

Google addressed this vulnerability in the Chrome 88.0.4324.96 stable channel release on January 19, 2021. The fix corrects the memory management issue in the WebRTC SCTP implementation to prevent the use after free condition. Organizations should deploy this update through their standard browser management processes. For complete release notes, see the Google Chrome Stable Update announcement.

Workarounds

• Disable WebRTC functionality via Chrome enterprise policies if immediate patching is not feasible using the WebRtcAllowLegacyTLSProtocols or similar policies
• Implement network-level filtering to block potentially malicious SCTP traffic
• Use browser isolation technologies to contain potential exploitation attempts
• Restrict user access to untrusted websites that may host exploit code

# Chrome Enterprise Policy Configuration Example
# Disable WebRTC via registry (Windows) as temporary mitigation
reg add "HKLM\SOFTWARE\Policies\Google\Chrome" /v WebRtcUdpPortRange /t REG_SZ /d "10000-10000" /f

# Verify Chrome version for compliance
google-chrome --version
# Ensure output shows 88.0.4324.96 or higher