EUVD-2025-18964

Comprehensive Technical Analysis of EUVD-2025-18964

1. Vulnerability Assessment and Severity Evaluation

The vulnerability described in EUVD-2025-18964 is an OS command injection vulnerability affecting various models of E-Series Linksys routers. The vulnerability exists in the /tmUnblock.cgi and /hndUnblock.cgi endpoints over HTTP on port 8080. The CGI scripts improperly process user-supplied input passed to the ttcp_ip parameter without sanitization, allowing unauthenticated attackers to inject shell commands.

Severity Evaluation:

• CVSS Base Score: 10.0
• CVSS Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H

The high CVSS score of 10.0 indicates a critical vulnerability. The attack vector (AV:N) is network-based, requiring low complexity (AC:L) and no authentication (PR:N). The impact on confidentiality, integrity, and availability is high (VC:H, VI:H, VA:H), and the scope change (SC:H) indicates that the vulnerability can affect components beyond the initial security scope.

2. Potential Attack Vectors and Exploitation Methods

Attack Vectors:

• Unauthenticated Remote Command Injection: Attackers can exploit the vulnerability by sending crafted HTTP requests to the affected endpoints, injecting arbitrary shell commands.
• Worm Propagation: The vulnerability is exploited in the wild by the "TheMoon" worm, which deploys a MIPS ELF payload to enable arbitrary code execution on the router.

Exploitation Methods:

• Direct Exploitation: Attackers can directly send malicious HTTP requests to the vulnerable endpoints to execute arbitrary commands.
• Automated Exploitation: The "TheMoon" worm demonstrates automated exploitation, where the worm scans for vulnerable routers and propagates itself by injecting malicious payloads.

3. Affected Systems and Software Versions

The vulnerability affects various models of Linksys E-Series routers, including but not limited to:

• E1200 v1 (versions ≤1.0.04)
• E1550 (versions ≤1.0.03)
• E3000 (versions <1.0.06)
• E1000 v1 (versions <2.1.03)
• E4200 (versions <1.0.06)
• E3200 (versions <1.0.05)
• E2000 (all versions)
• E2100L v1 (versions ≤1.0.05)
• E1500 v1 (versions <1.0.06)
• E900 v1 (versions <1.0.04)
• E2500 v1/v2 (versions <2.0.00)

Additionally, other Linksys products such as WAG/WAP/WES/WET/WRT-series router models and Wireless-N access points and routers may be affected.

4. Recommended Mitigation Strategies

Immediate Mitigation:

• Network Segmentation: Isolate affected routers from critical networks to limit the potential impact of exploitation.
• Firewall Rules: Implement firewall rules to block access to port 8080 from untrusted sources.
• Firmware Updates: Apply the latest firmware updates provided by Linksys as soon as they are available.

Long-Term Mitigation:

• Regular Patching: Establish a regular patching and update schedule for all network devices.
• Intrusion Detection Systems (IDS): Deploy IDS to monitor for suspicious activity and potential exploitation attempts.
• User Education: Educate users on the importance of updating firmware and the risks associated with outdated devices.

5. Impact on European Cybersecurity Landscape

The widespread use of Linksys routers in both residential and small business environments poses a significant risk to the European cybersecurity landscape. The vulnerability's exploitation by the "TheMoon" worm highlights the potential for large-scale, automated attacks that can compromise network security, exfiltrate data, and disrupt services. The critical nature of the vulnerability underscores the need for robust cybersecurity measures and regular updates to mitigate such risks.

6. Technical Details for Security Professionals

Vulnerability Details:

• Endpoints: /tmUnblock.cgi and /hndUnblock.cgi
• Parameter: ttcp_ip
• Port: 8080
• Exploitation: Unsanitized user input allows for shell command injection.

Detection and Response:

• Log Analysis: Monitor router logs for unusual activity, particularly requests to the vulnerable endpoints.
• Network Monitoring: Use network monitoring tools to detect and analyze suspicious traffic patterns.
• Incident Response: Develop an incident response plan that includes steps for identifying, containing, and remediating compromised routers.

References:

• SANS Internet Storm Center Diary
• Exploit Database Entry
• VulnCheck Advisories
• VulnCheck Advisories

By addressing this vulnerability promptly and comprehensively, organizations can significantly reduce the risk of exploitation and protect their networks from potential attacks.