Software Engineering Institute

CWE-255: Credentials Management - CVE-2015-7280

The ReadyNet WRT300N-DD Wireless Router web administration interface uses non-random default credentials of admin:admin. A local area network attacker can gain privileged access to a vulnerable device's web management interfaces or leverage default credentials in remote attacks such as cross-site request forgery.

CWE-352: Cross-Site Request Forgery (CSRF) - CVE-2015-7281

The ReadyNet WRT300N-DD contains a global CSRF vulnerability. An attacker can perform actions with the same permissions as a victim user, provided the victim has an active session and is induced to trigger the malicious request. Note that in combination with default credentials, an attacker can establish an active session as part of an attack and therefore would not require a victim to be logged in.

The CVSS score below reflects CVE-2015-7281.

CWE-330: Use of Insufficiently Random Values - CVE-2015-7282

The ReadyNet WRT300N-DD uses static source ports for all DNS queries originating from the local area network (LAN). An attacker with the ability to spoof DNS responses can cause WRT300N-DD LAN clients to contact incorrect or malicious hosts under the attacker's control.

The following graph shows a distribution of 330 DNS queries captured on the WAN port of the WRT300N-DD:

A remote, unauthenticated attacker may be able to spoof DNS responses to cause WRT300N-DD LAN clients to contact attacker-controlled hosts or induce an authenticated user into making an unintentional request to the web server that will be treated as an authentic request. A local area network attacker can take complete control of a device using default admin credentials.

The CERT/CC is currently unaware of a practical solution to this problem. Until these vulnerabilities are addressed, users should consider the following workarounds.

Restrict access and use strong passwords

As a general good security practice, only allow trusted hosts to connect to the LAN. Implement strong passwords for WiFi and for the web management interface. Strong passwords can help to prevent blind guessing attempts that would establish sessions for CSRF attacks. LAN hosts should not browse the Internet while the web management interface has an active session in a browser tab.

Note that there are no practical workarounds for the DNS spoofing vulnerability, as general users are unlikely to be able to monitor traffic entering the router's WAN port.