CVE-2019-1300
📋 TL;DR
This is a remote code execution vulnerability in Microsoft Edge's Chakra JavaScript engine that allows attackers to execute arbitrary code by exploiting memory corruption when handling objects. It affects users running vulnerable versions of Microsoft Edge on Windows systems. Successful exploitation could lead to complete system compromise.
💻 Affected Systems
- Microsoft Edge
📦 What is this software?
Chakracore by Microsoft
Edge by Microsoft
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise with attacker gaining full control over the victim's system, enabling data theft, ransomware deployment, or persistent backdoor installation.
Likely Case
Browser compromise leading to session hijacking, credential theft, and lateral movement within the network from the infected endpoint.
If Mitigated
Limited impact due to browser sandboxing and exploit mitigations, potentially resulting in browser crash or denial of service.
🎯 Exploit Status
Exploitation requires user interaction such as visiting a malicious website. The vulnerability is in the JavaScript engine, making it accessible via web content.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Microsoft Edge security update from September 10, 2019
Vendor Advisory: https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2019-1300
Restart Required: Yes
Instructions:
1. Open Windows Update settings. 2. Check for updates. 3. Install the September 2019 cumulative update for Windows. 4. Restart the system to complete installation.
🔧 Temporary Workarounds
Disable JavaScript
windowsDisable JavaScript in Microsoft Edge to prevent exploitation via malicious websites
Use Application Control
windowsImplement application whitelisting to prevent unauthorized code execution
🧯 If You Can't Patch
- Migrate to Chromium-based Microsoft Edge which is not affected by this vulnerability
- Implement network segmentation and restrict browser access to sensitive systems
🔍 How to Verify
Check if Vulnerable:
Check Microsoft Edge version by navigating to edge://settings/help and verifying version is older than the September 2019 updateCheck Version:
In Edge browser, navigate to edge://settings/help or check Windows Update historyVerify Fix Applied:
Verify Windows Update history shows installation of September 2019 cumulative update (KB4512578 for 1903, KB4515384 for 1809, etc.)📡 Detection & Monitoring
Log Indicators:
- Unexpected Edge browser crashes
- Suspicious process creation from Edge
- Unusual network connections from Edge process
Network Indicators:
- Traffic to known malicious domains hosting exploit code
- Unusual outbound connections following Edge usage
SIEM Query:
Process Creation where ParentImage contains 'msedge.exe' AND (CommandLine contains suspicious patterns OR Image contains unusual paths)