CVE-2019-0739
📋 TL;DR
This vulnerability allows remote attackers to execute arbitrary code on affected systems by exploiting a memory corruption flaw in Microsoft Edge's scripting engine. Attackers can craft malicious web content that triggers the vulnerability when visited by users. All users running vulnerable versions of Microsoft Edge are affected.
💻 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 machine, enabling data theft, ransomware deployment, or persistent backdoor installation.
Likely Case
Malicious code execution in the context of the current user, allowing data exfiltration, credential theft, and lateral movement within the network.
If Mitigated
Limited impact with proper network segmentation and application control preventing successful exploitation or limiting damage scope.
🎯 Exploit Status
Exploitation requires user to visit malicious website or open crafted content. No authentication required for initial access.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Microsoft Edge version with security update from April 2019
Vendor Advisory: https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2019-0739
Restart Required: Yes
Instructions:
1. Open Windows Update settings. 2. Check for updates. 3. Install all available security updates. 4. Restart system if prompted.
🔧 Temporary Workarounds
Disable JavaScript in Edge
windowsPrevents exploitation by disabling JavaScript execution in Microsoft Edge
Settings > Advanced settings > View advanced settings > Use Adobe Flash Player (toggle off)
Settings > Advanced settings > View advanced settings > JavaScript (toggle off)
Use Application Control
windowsRestrict execution of Microsoft Edge or block access to untrusted websites
🧯 If You Can't Patch
- Implement network segmentation to isolate vulnerable systems
- Deploy web filtering to block access to malicious websites
🔍 How to Verify
Check if Vulnerable:
Check Microsoft Edge version in Settings > About Microsoft Edge. Compare against patched version from April 2019 security updates.Check Version:
msedge --versionVerify Fix Applied:
Verify Windows Update history shows April 2019 security updates installed and Microsoft Edge version is updated.📡 Detection & Monitoring
Log Indicators:
- Unexpected Edge crashes
- Suspicious process creation from Edge
- Unusual network connections from Edge process
Network Indicators:
- Traffic to known malicious domains
- Unusual outbound connections from user workstations
SIEM Query:
Process Creation where (Image contains 'msedge.exe' AND CommandLine contains suspicious patterns) OR (EventID=1000 AND ApplicationName contains 'MicrosoftEdge.exe')