CVE-2023-31740
📋 TL;DR
This is a command injection vulnerability in Linksys E2000 routers that allows authenticated attackers to execute arbitrary commands with shell privileges. Attackers with web management access can inject commands through specific parameters in the apply.cgi interface. Only Linksys E2000 routers with firmware version 1.0.06 are affected.
💻 Affected Systems
- Linksys E2000
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete compromise of the router allowing attackers to intercept all network traffic, install persistent backdoors, pivot to internal network devices, or use the router for botnet activities.
Likely Case
Attackers with stolen or default credentials gain shell access to modify router settings, intercept traffic, or use the router as a foothold for internal network attacks.
If Mitigated
With strong authentication and network segmentation, impact is limited to the router itself without allowing lateral movement to other systems.
🎯 Exploit Status
Exploit requires authentication but is trivial to execute once credentials are obtained.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Unknown
Vendor Advisory: http://linksys.com
Restart Required: No
Instructions:
Check Linksys website for firmware updates. If no patch exists, consider replacing the router with a supported model.
🔧 Temporary Workarounds
Disable Remote Management
allPrevent external access to web management interface
Access router admin panel > Administration > Management > Disable Remote Management
Change Default Credentials
allUse strong, unique passwords for router administration
Access router admin panel > Administration > Management > Change Password
🧯 If You Can't Patch
- Segment router on isolated network segment to limit lateral movement
- Implement network monitoring for suspicious traffic to/from router
🔍 How to Verify
Check if Vulnerable:
Check router firmware version in admin panel > Administration > Firmware UpgradeCheck Version:
curl -s http://router-ip/version.cgi | grep FirmwareVerify Fix Applied:
Verify firmware version is no longer 1.0.06📡 Detection & Monitoring
Log Indicators:
- Unusual POST requests to apply.cgi with WL_atten parameters
- Multiple failed login attempts followed by successful login
Network Indicators:
- Unusual outbound connections from router IP
- Traffic patterns suggesting command execution
SIEM Query:
source="router-logs" AND (uri="/apply.cgi" AND (param="WL_atten_bb" OR param="WL_atten_radio" OR param="WL_atten_ctl"))