Abstract
Industrial automation and control systems (IACS) play a key role in modern production facilities. On the one hand, they provide real-time functionality to the connected field devices. On the other hand, they get more and more connected to local networks and the internet in order to facilitate use cases promoted by “Industrie 4.0”. A lot of IACS are equipped with web servers that provide web applications for configuration and management purposes. If an attacker gains access to such a web application operated on an IACS, he can exploit vulnerabilities and possibly interrupt the critical automation process. Cyber security research for web applications is well-known in the office IT. There exist a lot of best practices and tools for testing web applications for different kinds of vulnerabilities. Security testing targets at discovering those vulnerabilities before they can get exploited. In order to enable IACS manufacturers and integrators to perform security tests for their devices, ISuTest was developed, a modular security testing framework for IACS.
This paper provides a classification of known types of web application vulnerabilities. Therefore, it makes use of the worst direct impact of a vulnerability. Based on this analysis, a subset of open-source vulnerability scanners to detect such vulnerabilities is selected to be integrated into ISuTest. Subsequently, the integration is evaluated. This evaluation is twofold: At first, willful vulnerable web applications are used. In a second step, seven real IACS, like a programmable logic controller, industrial switches and cloud gateways, are used. Both evaluation steps start with the manual examination of the web applications for vulnerabilities. They conclude with an automated test of the web applications using the vulnerability scanners automated by ISuTest.
The results show that the vulnerability scanners detected 53 % of the existing vulnerabilities. In a former study using commercial vulnerability scanners, 54 % of the security flaws could be found. While performing the analysis, 45 new vulnerabilities were detected. Some of them did not only break the web server but crashed the whole IACS, stopping the critical automation process. This shows that security testing is crucial in the industrial domain and needs to cover all services provided by the devices.
