CVE-2015-7251
📋 TL;DR
ZTE ZXHN H108N R1A devices have a hardcoded root password 'root', allowing remote attackers to gain full administrative control via TELNET. This affects all devices before firmware version ZTE.bhs.ZXHNH108NR1A.k_PE. Attackers can completely compromise the device and potentially pivot to internal networks.
💻 Affected Systems
- ZTE ZXHN H108N R1A
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete device takeover leading to network compromise, data exfiltration, malware deployment, and use as pivot point for internal attacks.
Likely Case
Remote attackers gain administrative access to modify configurations, intercept traffic, or disable security features.
If Mitigated
Limited impact if TELNET is disabled and strong perimeter controls prevent external access.
🎯 Exploit Status
Simple TELNET connection with username 'root' and password 'root' provides full access. Exploit code is publicly available.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: ZTE.bhs.ZXHNH108NR1A.k_PE or later
Vendor Advisory: https://www.kb.cert.org/vuls/id/391604
Restart Required: Yes
Instructions:
1. Download latest firmware from ZTE support site. 2. Log into device web interface. 3. Navigate to firmware update section. 4. Upload and apply new firmware. 5. Reboot device.
🔧 Temporary Workarounds
Disable TELNET service
allPrevent remote TELNET access to mitigate exploitation.
telnetd stop
disable telnet in web interface
Network access control
linuxBlock TELNET port 23 at firewall to prevent external access.
iptables -A INPUT -p tcp --dport 23 -j DROP
🧯 If You Can't Patch
- Isolate device in separate VLAN with strict access controls
- Implement network monitoring for TELNET connections and failed login attempts
🔍 How to Verify
Check if Vulnerable:
Attempt TELNET connection to device port 23 with username 'root' and password 'root'.Check Version:
Check web interface system info or use telnet command after loginVerify Fix Applied:
Verify firmware version is ZTE.bhs.ZXHNH108NR1A.k_PE or later in web interface, and TELNET login with 'root'/'root' fails.📡 Detection & Monitoring
Log Indicators:
- Successful TELNET logins from unusual IPs
- Multiple failed TELNET attempts
Network Indicators:
- TELNET connections to port 23
- Traffic patterns indicating device compromise
SIEM Query:
source_port=23 AND (event_type="authentication_success" OR username="root")🔗 References
- http://www.securityfocus.com/bid/77421
- https://www.exploit-db.com/exploits/38773/
- https://www.kb.cert.org/vuls/id/391604
- https://www.kb.cert.org/vuls/id/BLUU-9ZDJWA
- http://www.securityfocus.com/bid/77421
- https://www.exploit-db.com/exploits/38773/
- https://www.kb.cert.org/vuls/id/391604
- https://www.kb.cert.org/vuls/id/BLUU-9ZDJWA
