Comprehensive Technical Analysis of EUVD-2026-1746 (CVE-2025-7072)

Vulnerability: Hard-Coded Credentials in KAON CG3000TC/CG3000T Router Firmware

1. Vulnerability Assessment & Severity Evaluation

Vulnerability Overview

EUVD-2026-1746 (CVE-2025-7072) describes a critical authentication bypass vulnerability in KAON CG3000TC and CG3000T routers due to hard-coded credentials embedded in the firmware. These credentials are shared across all devices of the same model, allowing unauthenticated remote attackers to gain root-level access and execute arbitrary commands.

CVSS v4.0 Severity Analysis

Metric	Value	Explanation
Attack Vector (AV)	Network (N)	Exploitable remotely over the internet.
Attack Complexity (AC)	Low (L)	No specialized conditions required.
Attack Requirements (AT)	None (N)	No user interaction or prior access needed.
Privileges Required (PR)	None (N)	No authentication required.
User Interaction (UI)	None (N)	Exploitable without user action.
Vulnerable Confidentiality (VC)	High (H)	Full access to sensitive data (e.g., credentials, configurations).
Vulnerable Integrity (VI)	High (H)	Ability to modify firmware, configurations, or execute malicious code.
Vulnerable Availability (VA)	High (H)	Potential for denial-of-service (DoS) or persistent backdoor installation.
Subsequent Confidentiality (SC)	None (N)	No further impact beyond initial exploitation.
Subsequent Integrity (SI)	None (N)	No additional integrity impact post-exploitation.
Subsequent Availability (SA)	None (N)	No cascading availability impact.

Base Score: 9.3 (Critical)

• The vulnerability is trivially exploitable with no authentication required, leading to full system compromise.
• The high impact on confidentiality, integrity, and availability (CIA triad) justifies the critical severity rating.

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2. Potential Attack Vectors & Exploitation Methods

Primary Attack Vectors

1. Remote Exploitation via WAN Interface

   • Attackers can exploit the vulnerability without prior access to the local network.
   • Common attack surfaces:
     • Telnet/SSH (if exposed to the internet).
     • Web-based administration panel (if misconfigured for remote access).
     • UPnP or NAT-PMP (if enabled and improperly secured).

2. Local Network Exploitation

   • If the router is only accessible internally, attackers with LAN access (e.g., via Wi-Fi or Ethernet) can exploit the vulnerability.
   • Man-in-the-Middle (MitM) attacks could intercept credentials if the router uses unencrypted management protocols.

3. Supply Chain & Post-Compromise Attacks

   • If an attacker gains access to a single device, they can extract the hard-coded credentials and use them across all devices of the same model.
   • Firmware reverse engineering could reveal additional backdoors or misconfigurations.

Exploitation Steps

1. Reconnaissance

   • Identify vulnerable devices via Shodan, Censys, or mass scanning (e.g., searching for KAON CG3000 in HTTP banners).
   • Check for exposed management interfaces (e.g., http://<router-ip>/login.cgi).

2. Credential Extraction

   • Static Analysis: Extract firmware (via binwalk, Firmware Mod Kit) and search for hard-coded credentials.

     strings firmware.bin | grep -i "admin\|root\|password"
     

   • Dynamic Analysis: Intercept traffic (e.g., via Wireshark) to capture credentials during login attempts.

3. Exploitation

   • Unauthenticated Command Execution:
     • Use the hard-coded credentials to log in via Telnet/SSH or the web interface.
     • Execute arbitrary commands with root privileges (e.g., cat /etc/passwd, reboot, or install malware).
   • Persistence Mechanisms:
     • Modify startup scripts (/etc/init.d/rc.local) to maintain access.
     • Install backdoor users or malicious firmware updates.

4. Post-Exploitation

   • Lateral Movement: Pivot to other devices on the network.
   • Data Exfiltration: Steal sensitive data (e.g., Wi-Fi passwords, VPN configurations).
   • Botnet Recruitment: Enlist the router in a DDoS botnet (e.g., Mirai variants).

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3. Affected Systems & Software Versions

Vulnerable Products

Product	Vendor	Affected Versions	Fixed Version
KAON CG3000TC	KAON	< 1.00.67	1.00.67
KAON CG3000T	KAON	< 1.00.27	1.00.27

Deployment Context

• Consumer & SOHO (Small Office/Home Office) routers commonly deployed by ISPs in Europe.
• Potential large-scale impact due to:
  • Mass deployment by ISPs (e.g., bundled with internet subscriptions).
  • Lack of automatic updates in many consumer-grade routers.
  • End-of-life (EOL) devices that may never receive patches.

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4. Recommended Mitigation Strategies

Immediate Actions (For End Users & ISPs)

1. Apply Firmware Updates

   • KAON CG3000TC: Upgrade to v1.00.67 or later.
   • KAON CG3000T: Upgrade to v1.00.27 or later.
   • Automated updates: Enable if available (check router settings).

2. Disable Remote Management

   • Disable WAN-side access to the web interface, Telnet, and SSH.
   • Restrict management to LAN-only (if remote access is unnecessary).

3. Change Default Credentials

   • Even after patching, modify all default passwords (admin, Wi-Fi, etc.).
   • Use strong, unique passwords (12+ characters, mixed case, symbols).

4. Network Segmentation

   • Isolate IoT and router management traffic from critical business/laptop networks.
   • Use VLANs to separate guest and internal networks.

5. Monitor for Exploitation Attempts

   • Deploy IDS/IPS (e.g., Snort, Suricata) to detect:
     • Unauthorized login attempts.
     • Suspicious command execution (e.g., wget, curl, busybox).
   • Check router logs for unusual activity (e.g., failed login attempts, unexpected reboots).

Long-Term Mitigations (For Vendors & ISPs)

1. Secure Development Practices

   • Eliminate hard-coded credentials in firmware.
   • Implement secure credential storage (e.g., hashed passwords, TPM-based authentication).
   • Automated firmware updates with cryptographic verification.

2. Supply Chain Security

   • Vendor audits to ensure third-party components are vulnerability-free.
   • Firmware signing to prevent tampering.

3. ISP-Level Protections

   • Automated patch deployment for ISP-managed routers.
   • Network-level filtering to block known malicious IPs targeting routers.

4. User Awareness & Education

   • ISPs should notify customers about critical vulnerabilities.
   • Public advisories with clear remediation steps.

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5. Impact on the European Cybersecurity Landscape

Threat Landscape Implications

1. Mass Exploitation Potential

   • Botnet Recruitment: Vulnerable routers are prime targets for Mirai-like botnets, leading to DDoS attacks on European infrastructure.
   • Espionage & Surveillance: State-sponsored actors could exploit these routers for cyber espionage (e.g., monitoring traffic, intercepting communications).

2. Critical Infrastructure Risks

   • SOHO routers are often used in small businesses, healthcare, and government offices, increasing the risk of data breaches.
   • Supply chain attacks could leverage compromised routers to pivot into corporate networks.

3. Regulatory & Compliance Concerns

   • GDPR Violations: Unauthorized access to routers could lead to data leaks, resulting in fines under GDPR.
   • NIS2 Directive: EU member states must ensure critical infrastructure operators (including ISPs) secure their networks.

4. Geopolitical & Cyber Warfare Risks

   • State-sponsored APT groups (e.g., Russian, Chinese, Iranian) could exploit these vulnerabilities for cyber warfare (e.g., disrupting communications, conducting influence operations).
   • Hybrid warfare scenarios where compromised routers are used to amplify disinformation campaigns.

European Response & Coordination

• CERT-PL (Poland) has issued an advisory, indicating proactive monitoring by national CERTs.
• ENISA (European Union Agency for Cybersecurity) may include this in threat intelligence reports for member states.
• EU Cybersecurity Act could drive mandatory vulnerability disclosure for IoT devices.

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6. Technical Details for Security Professionals

Firmware Analysis & Exploitation

Step 1: Firmware Extraction

binwalk -e firmware.bin  # Extract filesystem
cd _firmware.bin.extracted/

• Common locations for hard-coded credentials:
  • /etc/passwd, /etc/shadow
  • /etc/config/ (configuration files)
  • /web/ (web interface scripts)

Step 2: Credential Discovery

grep -r "admin\|root\|password" .
strings squashfs-root/bin/* | grep -i "pass"

• Example Findings:

  admin:admin123
  root:toor
  support:support123
  

Step 3: Exploitation via Telnet/SSH

telnet <router-ip>  # Use extracted credentials

• Post-Exploitation Commands:

  cat /etc/passwd  # List users
  ps aux           # Check running processes
  netstat -tuln    # Identify open ports
  

Step 4: Web Interface Exploitation

• Burp Suite / OWASP ZAP can intercept and modify requests to bypass authentication.
• Example Attack:

  POST /login.cgi HTTP/1.1
  Host: <router-ip>
  User-Agent: Mozilla/5.0
  Content-Type: application/x-www-form-urlencoded
  
  username=admin&password=admin123&submit=Login
  

Detection & Forensics

Indicators of Compromise (IoCs)

IoC Type	Example
IP Addresses	Known C2 servers (e.g., 185.178.45.22)
Domains	mirai-botnet[.]xyz
File Hashes	MD5: d41d8cd98f00b204e9800998ecf8427e (malicious firmware)
Process Names	./mirai, ./bot, ./watchdog
Network Traffic	Unusual outbound connections to port 23 (Telnet) or 4444 (reverse shell)

Forensic Analysis

• Memory Dump Analysis:

  volatility -f memory.dump linux_pslist  # Check for malicious processes
  

• Log Analysis:
  • /var/log/messages (system logs)
  • /var/log/auth.log (authentication attempts)

Reverse Engineering & Exploit Development

• Ghidra / IDA Pro for firmware disassembly.
• QEMU Emulation to test exploits in a controlled environment.
• Metasploit Module Development (if no public exploit exists).

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Conclusion & Recommendations

Key Takeaways

• EUVD-2026-1746 (CVE-2025-7072) is a critical vulnerability with high exploitability and severe impact.
• Immediate patching is essential to prevent remote code execution, botnet recruitment, and data breaches.
• European organizations must prioritize securing SOHO routers, given their widespread deployment and historical targeting by threat actors.

Action Plan for Security Teams

1. Patch Management:

   • Deploy firmware updates for all KAON CG3000TC/CG3000T routers.
   • Automate updates where possible.

2. Network Hardening:

   • Disable remote management unless absolutely necessary.
   • Segment networks to limit lateral movement.

3. Threat Hunting:

   • Monitor for exploitation attempts (e.g., brute-force attacks, unusual command execution).
   • Deploy IoCs in SIEM/EDR solutions.

4. Vendor & ISP Coordination:

   • Pressure vendors to adopt secure development practices.
   • Work with ISPs to ensure automated patching for consumer devices.

5. Public Awareness:

   • Educate end users on router security best practices.
   • Publish advisories for affected organizations.

Final Risk Assessment

Factor	Risk Level	Justification
Exploitability	Critical	Trivial remote exploitation.
Impact	Critical	Full system compromise (RCE as root).
Prevalence	High	Mass deployment in Europe.
Mitigation Feasibility	Medium	Patching is straightforward but requires user/ISP action.
Threat Actor Interest	High	Attractive for botnets, APTs, and cybercriminals.

Overall Risk: CRITICAL (Immediate action required)

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References:

• NVD - CVE-2025-7072
• CERT-PL Advisory
• ENISA IoT Security Guidelines