IoT security issues: the researcher discovered serious vulnerabilities in MatrixSSL

SSL is the main Internet security tool that allows you to organize secure data exchange even on an untrusted network. However, implementing sustainable SSL is not such an easy task, errors in solving which can lead to large-scale problems, such as the Heartbleed vulnerability.

In the field of the Internet of things there is its own implementation of SSL - MatrixSSL, and as practice shows, with the level of its security, all is not well.

What is the problem

Such large-scale vulnerabilities raise questions about the implementation of secure development approaches and design process deficiencies used by many SSL implementers. In the midst of the Heartbleed scandal, there were even calls to stop using OpenSSL in favor of NSS, GnuTLS and Polar SSL. As for the devices of the so-called Internet of Things (Internet of Things, IoT), in this case, many security experts recommended using MatrixSSL - a compact SSL / TLS stack designed specifically for use in the IoT field.
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However, in 2015, the SEC Consult study was published, the authors of which were able to detect more than 80,000 network-connected devices that used the same encryption keys published in the MatrixSSL home repository. Tens of thousands of devices based on MatrixSSL can be found using the search engine Shodan.

Such devices are often network equipment like WiMAX gateways or cable modems of Internet providers. This means that the presence of critical vulnerabilities in the software used by these devices can lead to large-scale information security incidents.

And similar vulnerabilities were discovered by researchers — in 2016, Florian Weimer and Hanno Böck revealed information about the cryptographic problems of MatrixSSL — among other things, the possibility of stealing private encryption keys was discovered. After talking to Bock, Tripwire’s IB security researcher, Craig Young, decided to examine the security level of the X.509 MatrixSSL certificate more closely.

Using the American Fuzzy Lop tool (AFL), he managed to detect several serious vulnerabilities at once. Problems found include buffer overflow leading to code execution (CVE-2016-6890), buffer over-read vulnerability (CVE-2016-6891), and incorrect operation of the memory release mechanism in the x509FreeExtensions () module (CVE-2016-6892).

These errors can lead to serious problems. For example, in the event that a MatrixSSL-based system is used to process untrusted X.509 certificates - a common situation when authenticating a client application, then an attacker may be able to perform remote code execution. For a router or IoT devices, this means almost guaranteed full access with root privileges.

How to protect

According to Yang, manufacturers using MatrixSSL in their products were notified of the vulnerabilities found in September, and are already working on patches. MatrixSSL vendors and private users can download the latest firmware from the official Matrix SSL GitHub repository . Bug fixes are included in the b8dcfd875923da5a65ecfdbbe790ed63b1d33de3 commit for release 3.8.6.

Unfortunately, many MatrixSSL-based devices used in corporate networks will never be updated - not all IoT manufacturers will eventually release patches, and in the absence of an automatic update, users themselves are unlikely to do this.

All this raises an important question - instead of discussing more reliable tools to ensure protection on the Internet and the need to find their replacement, it is much more promising to think about implementing more advanced mechanisms for distributing updates and implementing safe software development approaches.