How to Implement TR-069 So You Avoid Vulnerabilities

In 2016, Mirai Worm exploited a vulnerability in the TR-064 protocol to extend it’s reach, disrupting vast connections across the world. It was a widely publicized event that naturally led to the concerns of how powerful such Distributed Denial of Service (DDoS) attacks could become.

One obvious victim of the Mirai Worm aftermath was TR-069 as some stakeholders remain unconvinced about the security of the protocol. It’s important to understand that the security issue isn’t necessarily in TR-064 or TR-069 itself. TR-069 rides on secure transport protocols. However, as with any other web service, a poor implementation may leave the system at risk of a breach.

Being one of the most widely deployed broadband management protocols globally, TR-069 has established quite a footprint. A small compromise in the system can be utilized to invite unauthorized people into the system, exposing millions of customers.

To ensure TR-069 is safe, there are a couple of things you should keep in mind while implementing the system:

Validate Parameter Data

Validating parameter data can help secure your CWMP system against code injection attacks. The Mirai Worm used one such technique known as shell injection which gave it control turning the target itself into a DoS participant. It wasn’t just corrupt, it corrupted badly.

Shell injection attacks take advantage of exposed systems to allow parameters that aren’t validated for escape characters to be executed as shell commands instead of being passed along as expected.

To prevent such issues, vendors must do thorough validation on parameters used in TR-069.

Run It Over a Secure Connection

By design, TR-069 is supposed to run over a secure transport layer. According to TR-069 Amendment 6 section 3.3: The use of TLS to transport the CPE WAN Management Protocol is RECOMMENDED, although the protocol MAY be used directly over a TCP connection instead. If TLS is not used, some aspects of security are sacrificed. Specifically, TLS provides confidentiality and data integrity and allows certificate-based authentication in lieu of shared secret-based authentication.

Like all web services, TR-069 should be run over a secure connection. You can use Cd Router's TR-069 add-on to test if your device will do certificate-based authentication correctly. It also includes a negative test you can use to be sure it will reject bad certificates.

Use Compliant Devices

Standard recommendations won’t work if the device itself violates best practices. To be sure, you’ll need to ensure the TR-069 device is certified. Broadband Forum’s BBF.069 CPE Certification Program helps service providers to vet devices for compliance.

By being certified, vendors can also prove the compliance of these devices to their customers and partners. The program discusses nearly everything you need to know about implementing TR-069, including securing the systems.

You can use CDRouter’s BBF.069 add-on to easily perform tests before, during and after being certified by an approved lab.

Close Open Connections

Since password type fields are write-only, TR-069 cannot expose user password data. However, in the event that things such as ACS URL need to be changed, the device is likely to expose some CWMP configuration functionality.

To avoid this, ensure the device knows the ACS URL ahead of time if you know the service provider deployment. Alternatively, you can completely remove TR-069 configurations from the user’s interface or limit it to specific users of the device OS, but not through the subscriber’s interface.

Note that such access can only be gained if the device is already compromised. To mitigate the underlying risk, make sure your TR-069 devices don’t leave exposed ports and applications. CDRouter’s nmap port scan can help you identify areas of vulnerability.

Also, make sure that the open HTTP port over which TR-069 uses a connection request mechanism is used as intended. On the devices, white-list servers using the connection request mechanism to avoid the interface being abused.

Final Word

While TR-069 is a safe protocol by design and intended use, the system requires so much integration that the room for error raises security concerns. By following a couple of best practices, you can avoid the more obvious vulnerabilities altogether and strengthen your system.

All it takes is some due diligence and a couple of robust tools to help you run the tests and apply fixes. Besides, there are guides for every step of the way to keep you aligned with industry standards.