Belkin Wi-Fi routers at risk from multiple vulnerabilities

Flaws have not been patched and there are no workarounds for many of them, says US CERT.

Belkin routers have several severe vulnerabilities, says US-CERT.
Belkin routers have several severe vulnerabilities, says US-CERT.

Wireless routers made by Belkin have been found to have several vulnerabilities, some of which have no workarounds.

According to an advisory by US-CERT, The Belkin N600 DB Wireless Dual Band N+ router model F9K1102 v2 with firmware version 2.10.17 has flaws that could allow a hacker to arbitrarily inject files, perform man-in-the-middle attacks and forge cross-site requests.

“A remote, unauthenticated attacker may be able to spoof DNS responses to cause vulnerable devices 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,” said the US-CERT advisory. “A LAN-based attacker can bypass authentication to take complete control of vulnerable devices.”

In May, security researcher Kafeine warned that more than 40 popular routers were vulnerable to cross-site request forgery pharming attacks.

According to US-CERT's advisory issued on Monday, DNS queries from the N600 such as those to resolve the names of firmware update and NTP servers, use predictable TXIDs that start at 0x0002 and increase incrementally. An attacker with the ability to spoof DNS responses can cause the router to contact incorrect or malicious hosts under the attacker's control.

The router also uses HTTP by default for checking and transmitting firmware update information to vulnerable routers. An attacker capable of conducting man-in-the-middle attacks can manipulate traffic to block updates or inject arbitrary files.

Belkin's device also by default does not set a password for the web management interface. A local area network (LAN) attacker can gain privileged access to the web management interface or leverage the default absence of credentials in remote attacks such as cross-site request forgery.

When a password is implemented in the Belkin N600 web management interface, authorisation is enforced client-side by the browser. By intercepting packets from the embedded server, an attacker can bypass authentication and gain full, privileged access to restricted pages of the web management interface.

Lastly, the router contains a global cross-site request forgery (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 default configurations lacking password protection, an attacker can establish an active session as part of an attack and does not require a victim to be logged in.

US-CERT said it was “currently unaware of a practical solution to this problem”. Until then US-CERT said that users should only allow trusted hosts to connect to the LAN.

“Implement strong passwords for WiFi and for the web management interface. While passwords do not provide any additional security against LAN-based attackers due to the authentication bypass vulnerability, 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,” it advised.

It warned that there are “no practical workarounds for the DNS spoofing or firmware over HTTP issues, as general users are unlikely to be able to monitor traffic entering the router's WAN port”.

Marios Kyriacou, founder of The Security Bureau, told SCMagazineUK.com that the vulnerabilities have been introduced through poor security practise that are very basic.

“Attackers with the ability to connect to the network would be able to access the management area of the router. They could then change any of the settings including redirecting legitimate users to malicious websites,” he said.

He added that it's unlikely that large organisations would be using these devices.

“However, they could be using them as part of their guest networks. Small and medium enterprises (SMEs) are more likely to be using these devices as they are affordable. Therefore, it's SMEs that should be concerned,” said Kyriacou.

He added that it was advisable to log all access attempts to the web management interface and keep access to this at a minimum allowing few staff to access this. 

TK Keanini, CTO at Lancope, told SC that this is not the first time – and most likely not the last time – that these devices would have critical vulnerabilities that needed to be patched. “Get used to it folks because as everything in the known universe becomes connected to the Internet, this will only increase,” he said.

“The alarming thing about this is that most people who run these products don't even take notice of the model they are running or pay any attention to the advisory. I do my part to post this information to my social networks in a Neighbourhood Watch type of effort and encourage everyone to do the same. Help your fellow internet connected friend be safe. Security is a process and you need to be part of that process,” he added.