CVE-2023-23040
📋 TL;DR
This vulnerability in TP-Link TL-WR940N V6 routers allows attackers to potentially crack admin passwords due to the use of weak MD5 hashing for authentication. Attackers who gain access to password hashes could brute-force them to obtain administrative credentials. This affects users of TP-Link TL-WR940N V6 routers with firmware version 3.19.1 Build 180119.
💻 Affected Systems
- TP-Link TL-WR940N V6
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Attackers gain administrative access to the router, enabling them to reconfigure network settings, intercept traffic, install malware, or use the device as part of a botnet.
Likely Case
Attackers with network access could capture authentication traffic and attempt to crack MD5 hashes to gain administrative privileges.
If Mitigated
With proper network segmentation and firewall rules, the attack surface is reduced, limiting exposure to internal threats only.
🎯 Exploit Status
Exploitation requires network access to capture authentication traffic and computational resources to crack MD5 hashes.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Check TP-Link support for latest firmware
Vendor Advisory: https://www.tp-link.com/en/support/download/tl-wr940n/#Firmware
Restart Required: Yes
Instructions:
1. Visit TP-Link support page for TL-WR940N. 2. Download latest firmware. 3. Log into router admin interface. 4. Navigate to System Tools > Firmware Upgrade. 5. Upload and install new firmware. 6. Reboot router.
🔧 Temporary Workarounds
Disable remote administration
allPrevents external attackers from accessing admin interface
Change admin password to complex value
allMakes MD5 hash cracking more difficult
🧯 If You Can't Patch
- Segment router on isolated network segment
- Implement network monitoring for authentication attempts
🔍 How to Verify
Check if Vulnerable:
Check router firmware version in admin interface under System Tools > Firmware UpgradeCheck Version:
No CLI command - check via web interfaceVerify Fix Applied:
Verify firmware version has been updated to a version after 3.19.1 Build 180119📡 Detection & Monitoring
Log Indicators:
- Multiple failed authentication attempts
- Unusual admin login times/locations
Network Indicators:
- HTTP authentication traffic to router admin interface
- Unusual outbound connections from router
SIEM Query:
source="router" AND (event_type="authentication" AND result="failure")