Application Security Testing

Security testing techniques scour for vulnerabilities or security holes in applications. These vulnerabilities leave applications open to exploitation. Ideally, security testing is implemented throughout the entire software development life cycle (SDLC) so that vulnerabilities may be addressed in a timely and thorough manner. Unfortunately, testing is often conducted as an afterthought at the end of the development cycle. With the growth of Continuous delivery and DevOps as popular software development and deployment models, continuous security models are becoming more popular.

Vulnerability scanners, and more specifically web application scanners, otherwise known as penetration testing tools (i.e. ethical hacking tools) have been historically used by security organizations within corporations and security consultants to automate the security testing of http request/responses; however, this is not a substitute for the need for actual source code review. Physical code reviews of an application's source code can be accomplished manually or in an automated fashion. Given the common size of individual programs (often 500,000 lines of code or more), the human brain cannot execute a comprehensive data flow analysis needed in order to completely check all circuitous paths of an application program to find vulnerability points. The human brain is suited more for filtering, interrupting and reporting the outputs of automated source code analysis tools available commercially versus trying to trace every possible path through a compiled code base to find the root cause level vulnerabilities.

There are many kinds of automated tools for identifying vulnerabilities in applications. Some require a great deal of security expertise to use and others are designed for fully automated use. The results are dependent on the types of information (source, binary, HTTP traffic, configuration, libraries, connections) provided to the tool, the quality of the analysis, and the scope of vulnerabilities covered. Common technologies used for identifying application vulnerabilities include:

Static Application Security Testing (SAST) is a technology that is frequently used as a Source Code Analysis tool. The method analyzes source code for security vulnerabilities prior to the launch of an application and is used to strengthen code. This method produces fewer false positives but for most implementations requires access to an application's source code and requires expert configuration and lots of processing power.

Dynamic Application Security Testing (DAST) is a technology, which is able to find visible vulnerabilities by feeding a URL into an automated scanner. This method is highly scalable, easily integrated and quick. DAST's drawbacks lie in the need for expert configuration and the high possibility of false positives and negatives.

Interactive Application Security Testing (IAST) is a solution that assesses applications from within using software instrumentation. This technique allows IAST to combine the strengths of both SAST and DAST methods as well as providing access to code, HTTP traffic, library information, backend connections and configuration information. Some IAST products require the application to be attacked, while others can be used during normal quality assurance testing.