CVE-2023-25437
📋 TL;DR
This vulnerability in vTech VCS754 business phones exposes SIP credentials through cleartext passwords in raw HTML. Attackers can gain escalated privileges and access sensitive information. Affects vTech VCS754 version 1.1.1.A before 1.1.1.H.
💻 Affected Systems
- vTech VCS754 business phones
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete compromise of phone system, unauthorized calls, eavesdropping on communications, and lateral movement to other network systems.
Likely Case
SIP credential theft leading to unauthorized phone calls, toll fraud, and potential access to voicemail systems.
If Mitigated
Limited to credential exposure without further system compromise if proper network segmentation and monitoring are in place.
🎯 Exploit Status
Exploitation requires accessing the phone's web interface HTML source where credentials are visible in cleartext.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 1.1.1.H
Vendor Advisory: https://yechiel.xyz/vulnerability-in-vtechs-vcs754a-business-phones-exposes-sip-credentials
Restart Required: Yes
Instructions:
1. Download firmware version 1.1.1.H from vTech support. 2. Upload firmware to phone web interface. 3. Apply update. 4. Reboot phone.
🔧 Temporary Workarounds
Restrict web interface access
linuxBlock external access to phone web interfaces using firewall rules.
iptables -A INPUT -p tcp --dport 80 -j DROP
iptables -A INPUT -p tcp --dport 443 -j DROP
Change SIP credentials
allChange SIP passwords to limit exposure if credentials are compromised.
🧯 If You Can't Patch
- Isolate phones on separate VLAN with strict firewall rules
- Disable web interface access entirely if not required
🔍 How to Verify
Check if Vulnerable:
Access phone web interface, view page source, search for SIP password fields to see if credentials are in cleartext.Check Version:
Check phone web interface status page or use: curl -s http://phone-ip/status | grep FirmwareVerify Fix Applied:
After patching, verify credentials are no longer visible in HTML source and check firmware version is 1.1.1.H or later.📡 Detection & Monitoring
Log Indicators:
- Multiple failed login attempts to phone web interface
- Unusual SIP registration attempts from new IPs
Network Indicators:
- HTTP requests to phone web interfaces from unexpected sources
- SIP traffic from unauthorized endpoints
SIEM Query:
source="phone-web-logs" AND (url="*password*" OR status=200 AND user_agent="*scanner*")