Search-based Multi-Vulnerability Testing of XML Injections in Web Applications

in Empirical Software Engineering (2019), 24(6), 36963729

Modern web applications often interact with internal web services, which are not directly accessible to users. However, malicious user inputs can be used to exploit security vulnerabilities in web ... [more ▼]

Modern web applications often interact with internal web services, which are not directly accessible to users. However, malicious user inputs can be used to exploit security vulnerabilities in web services through the application front-ends. Therefore, testing techniques have been proposed to reveal security flaws in the interactions with back-end web services, e.g., XML Injections (XMLi). Given a potentially malicious message between a web application and web services, search-based techniques have been used to find input data to mislead the web application into sending such a message, possibly compromising the target web service. However, state-of-the-art techniques focus on (search for) one single malicious message at a time. Since, in practice, there can be many different kinds of malicious messages, with only a few of them which can possibly be generated by a given front-end, searching for one single message at a time is ineffective and may not scale. To overcome these limitations, we propose a novel co-evolutionary algorithm (COMIX) that is tailored to our problem and uncover multiple vulnerabilities at the same time. Our experiments show that COMIX outperforms a single-target search approach for XMLi and other multi-target search algorithms originally defined for white-box unit testing. [less ▲]

Automated and Effective Security Testing for XML-based Vulnerabilities

Doctoral thesis (2017)

Nowadays, the External Markup Language (XML) is the most commonly used technology in web services for enabling service providers and consumers to exchange data. XML is also widely used to store data and ... [more ▼]

Nowadays, the External Markup Language (XML) is the most commonly used technology in web services for enabling service providers and consumers to exchange data. XML is also widely used to store data and configuration files that control the operation of software systems. Nevertheless, XML suffers from several well-known vulnerabilities such as XML Injections (XMLi). Any exploitation of these vulnerabilities might cause serious and undesirable consequences, e.g., denial of service and accessing or modifying highly-confidential data. Fuzz testing techniques have been investigated in the literature to detect XMLi vulnerabilities. However, their success rate tends to be very low since they cannot generate complex test inputs required for the detection of these vulnerabilities. Furthermore, these approaches are not effective for real-world complex XML-based enterprise systems, which are composed of several components including front-end web applications, XML gateway/firewall, and back-end web services. In this dissertation, we propose several automated security testing strategies for detecting XML-based vulnerabilities. In particular, we tackle the challenges of security testing in an industrial context. Our proposed strategies, target various and complementary aspects of security testing for XML-based systems, e.g., test case generation for XML gateway/firewall. The development and evaluation of these strategies have been done in close collaboration with a leading financial service provider in Luxembourg/Switzerland, namely SIX Payment Services (formerly known as CETREL S.A.). SIX Payment Services processes several thousand financial transactions daily, providing a range of financial services, e.g., online payments, issuing of credit and debit cards. The main research contributions of this dissertation are: -A large-scale and systematic experimental assessment for detecting vulnerabilities in numerous widely-used XML parsers and the underlying systems using them. In particular, we targeted two common XML parser’s vulnerabilities: (i) XML Billion Laughs (BIL), and (ii) XML External Entities (XXE). - A novel automated testing approach, that is based on constraint-solving and input mutation techniques, to detect XMLi vulnerabilities in XML gateway/firewall and back-end web services. - A black-box search-based testing approach to detect XMLi vulnerabilities in front-end web applications. Genetic algorithms are used to search for inputs that can manipulate the application to generate malicious XML messages. - An in-depth analysis of various search algorithms and fitness functions, to improve the search-based testing approach for front-end web applications. - Extensive evaluations of our proposed testing strategies on numerous real-world industrial web services, XML gateway/firewall, and web applications as well as several open-source systems. [less ▲]

Automated and Effective Testing of Web Services for XML Injection Attacks

in ISSTA'16-The International Symposium on Software Testing and Analysis, Saarbrücken 18-20 July 2016 (2016, July 18)

XML is extensively used in web services for integration and data exchange. Its popularity and wide adoption make it an attractive target for attackers and a number of XML-based attack types have been ... [more ▼]

XML is extensively used in web services for integration and data exchange. Its popularity and wide adoption make it an attractive target for attackers and a number of XML-based attack types have been reported recently. This raises the need for cost-effective, automated testing of web services to detect XML-related vulnerabilities, which is the focus of this paper. We discuss a taxonomy of the types of XML injection attacks and use it to derive four different ways to mutate XML messages, turning them into attacks (tests) automatically. Further, we consider domain constraints and attack grammars, and use a constraint solver to generate XML messages that are both malicious and valid, thus making it more difficult for any protection mechanism to recognise them. As a result, such messages have a better chance to detect vulnerabilities. Our evaluation on an industrial case study has shown that a large proportion (78.86%) of the attacks generated using our approach could circumvent the first layer of security protection, an XML gateway (firewall), a result that is much better than what a state-of-the-art tool based on fuzz testing could achieve. [less ▲]