CVE-2018-25316 Overview
Tenda W308R v2 V5.07.48 contains a cookie session weakness vulnerability that allows unauthenticated attackers to modify DNS settings by exploiting insufficient session validation. Attackers can send GET requests to the goform/AdvSetDns endpoint with a crafted admin language cookie to change DNS servers and redirect user traffic to malicious sites.
Critical Impact
Unauthenticated attackers can hijack DNS settings on affected routers, enabling traffic interception, phishing attacks, and malware distribution to all connected devices.
Affected Products
- Tenda W308R v2 V5.07.48
Discovery Timeline
- 2026-04-29 - CVE CVE-2018-25316 published to NVD
- 2026-04-29 - Last updated in NVD database
Technical Details for CVE-2018-25316
Vulnerability Analysis
This vulnerability is classified under CWE-290 (Authentication Bypass by Spoofing), which occurs when authentication mechanisms can be circumvented through impersonation or spoofing techniques. The Tenda W308R v2 router firmware fails to properly validate session cookies before processing administrative requests, allowing attackers to bypass authentication entirely.
The vulnerability exists in the router's web management interface, specifically in how it handles administrative session validation. The firmware does not adequately verify that incoming requests originate from authenticated administrative sessions. By crafting a specific language cookie that mimics an admin session, attackers can trick the router into accepting unauthorized configuration changes.
Root Cause
The root cause stems from insufficient session validation in the router's web interface. The goform/AdvSetDns endpoint processes DNS configuration changes without properly verifying the authenticity of the requesting session. The router relies on weak cookie-based authentication that can be easily spoofed, rather than implementing robust session management with cryptographically secure tokens.
Attack Vector
The attack is network-based and requires no authentication or user interaction. An attacker on the same network or with access to the router's management interface can exploit this vulnerability by sending specially crafted HTTP GET requests to the vulnerable endpoint. The attacker constructs a request to goform/AdvSetDns with manipulated cookie values that simulate an administrative session.
Upon successful exploitation, the attacker can modify the router's DNS server settings to point to attacker-controlled DNS servers. This enables DNS hijacking attacks where all DNS queries from devices connected to the compromised router are redirected to malicious servers. Attackers can then redirect users to phishing sites, inject malware, or intercept sensitive communications.
Technical details and proof-of-concept information can be found in the Exploit-DB #44373 entry and the VulnCheck Advisory on Tenda W308R V2.
Detection Methods for CVE-2018-25316
Indicators of Compromise
- Unexpected DNS server configuration changes on Tenda W308R v2 routers
- HTTP GET requests to /goform/AdvSetDns endpoint from unauthorized sources
- DNS server settings pointing to unknown or suspicious IP addresses
- Unusual network traffic patterns indicating DNS hijacking attempts
Detection Strategies
- Monitor HTTP access logs for requests to /goform/AdvSetDns endpoints
- Implement network intrusion detection rules to flag unauthorized configuration change attempts
- Periodically audit DNS settings on affected routers to detect unauthorized modifications
- Deploy network monitoring to identify traffic to known malicious DNS servers
Monitoring Recommendations
- Enable logging on network perimeter devices to capture traffic to router management interfaces
- Configure alerts for any DNS configuration changes on network infrastructure devices
- Implement network segmentation to isolate router management interfaces from general network traffic
- Monitor for DNS resolution anomalies that could indicate DNS hijacking
How to Mitigate CVE-2018-25316
Immediate Actions Required
- Restrict access to the router's web management interface to trusted IP addresses only
- Disable remote management capabilities if not required
- Segment the management network from untrusted networks
- Monitor DNS settings for unauthorized changes
- Consider replacing end-of-life devices with supported alternatives
Patch Information
No official vendor patch has been identified in the available data. The Tenda W308R v2 is a legacy device that may no longer receive firmware updates. Organizations should consult the VulnCheck Advisory on Tenda W308R V2 for the latest remediation guidance.
Workarounds
- Restrict management interface access to localhost or specific trusted IP addresses only
- Implement firewall rules to block external access to the router's web interface on port 80/443
- Place the router behind a firewall that can filter and log access attempts to management endpoints
- Consider replacing the affected device with a modern, supported router that implements proper session management
# Configuration example - Firewall rule to restrict management interface access
# Block external access to router management interface
iptables -A INPUT -p tcp --dport 80 -s ! 192.168.1.0/24 -j DROP
iptables -A INPUT -p tcp --dport 443 -s ! 192.168.1.0/24 -j DROP
# Log attempts to access management interface from untrusted sources
iptables -A INPUT -p tcp --dport 80 -j LOG --log-prefix "Router-Mgmt-Access: "
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
