Application security (short AppSec) includes all tasks that introduce a secure software development life cycle to development teams. Its final goal is to improve security practices and, through that, to find, fix and preferably prevent security issues within applications. It encompasses the whole application life cycle from requirements analysis, design, implementation, verification as well as maintenance.
Different approaches will find different subsets of the security vulnerabilities lurking in an application and are most effective at different times in the software lifecycle. They each represent different tradeoffs of time, effort, cost and vulnerabilities found.
- Design review. Before code is written the application's architecture and design can be reviewed for security problems. A common technique in this phase is the creation of a threat model.
- Whitebox security review, or code review. This is a security engineer deeply understanding the application through manually reviewing the source code and noticing security flaws. Through comprehension of the application, vulnerabilities unique to the application can be found.
- Blackbox security audit. This is only through use of an application testing it for security vulnerabilities, no source code required.
- Automated Tooling. Many security tools can be automated through inclusion into the development or testing environment. Examples of those are automated DAST/SAST tools that are integrated into code editor or CI/CD platforms.
- Coordinated vulnerability platforms. These are hacker-powered application security solutions offered by many websites and software developers by which individuals can receive recognition and compensation for reporting bugs.
Web application security
Web application security is a branch of information security that deals specifically with security of websites, web applications and web services. At a high level, web application security draws on the principles of application security but applies them specifically to internet and web systems.
Web Application Security Tools are specialized tools for working with HTTP traffic, e.g., Web application firewalls.
The Open Web Application Security Project (OWASP) provides free and open resources. It is led by a non-profit called The OWASP Foundation. The OWASP Top 10 - 2017 is the published result of recent research based on comprehensive data compiled from over 40 partner organizations. From this data, approximately 2.3 million vulnerabilities were discovered across over 50,000 applications. According to the OWASP Top 10 - 2017, the ten most critical web application security risks include:
- Broken authentication
- Sensitive data exposure
- XML external entities (XXE)
- Broken access control
- Security misconfiguration
- Cross-site scripting (XSS)
- Insecure deserialization
- Using components with known vulnerabilities
- Insufficient logging and monitoring
Tooling for 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.
There are many kinds of automated tools for identifying vulnerabilities in applications. Common tool categories used for identifying application vulnerabilities include:
- Static Application Security Testing (SAST) analyzes source code for security vulnerabilities during an application's development. Compared to DAST, SAST can be utilized even before the application is in an executable state. As SAST has access to the full source-code it is a white-box approach. This can yield more detailed results but can result in many false-positives that need to be manually verified.
- Dynamic Application Security Testing (DAST, often called Vulnerability scanners) automatically detects vulnerabilities by crawling and analyzing web sites. This method is highly scalable, easily integrated and quick. DAST tools are well suited for dealing with low-level attacks such as injection flaws but are not well suited to detect high-level flaws, e.g., logic or business-logic flaws. Fuzzing, tools are commonly used for input testing.
- Interactive Application Security Testing (IAST) assesses applications from within using software instrumentation. This combines 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.[promotional source?][promotional source?]
- Runtime application self-protection augment existing applications to provide intrusion detection and prevention from within an application runtime.
- Dependency scanners (also called Software Composition Analysis) try to detect usage of software components with known vulnerabilities. These tools can either work on-demand, e.g., during the source code build process, or periodically.
- Abstraction is the idea of making more complex things less complex.
Security standards and regulations
- CERT Secure Coding
- ISO/IEC 27034-1:2011 Information technology — Security techniques — Application security -- Part 1: Overview and concepts
- ISO/IEC TR 24772:2013 Information technology — Programming languages — Guidance to avoiding vulnerabilities in programming languages through language selection and use
- NIST Special Publication 800-53
- OWASP ASVS: Web Application Security Verification Standard
- Application service architecture (ASA)
- Data security
- Mobile Security
- Security Development Lifecycle
- Trustworthy Computing Security Development Lifecycle
- Happe, Andreas (3 June 2021). "What is AppSec anyways?". snikt.net.
- "Web Application Security Overview". 2015-10-23.
- Shuaibu, Bala Musa; Norwawi, Norita Md; Selamat, Mohd Hasan; Al-Alwani, Abdulkareem (2013-01-17). "Systematic review of web application security development model". Artificial Intelligence Review. 43 (2): 259–276. doi:10.1007/s10462-012-9375-6. ISSN 0269-2821. S2CID 15221613.
- Korolov, Maria (Apr 27, 2017). "Latest OWASP Top 10 looks at APIs, web apps: The new OWASP Top 10 list is out, and while most of it remains the same, there are new additions focusing on web applications and APIs". CSO. ProQuest 1892694046.
- "OWASP Top 10 - 2017: The Ten Most Critical Web Application Security Risks" (PDF). Open Web Application Security Project. 2017. Retrieved June 30, 2018.
- "Web Application Vulnerability Scanners". NIST.
- "Fuzzing". OWASP.
- Williams, Jeff (2 July 2015). "I Understand SAST and DAST But What is an IAST and Why Does it Matter?". Contrast Security. Retrieved 10 April 2018.
- Velasco, Roberto (7 May 2020). "What is IAST? All About Interactive Application Security Testing". Hdiv Security. Retrieved 7 May 2020.
- Abezgauz, Irene (February 17, 2014). "Introduction to Interactive Application Security Testing". Quotium.
- Rohr, Matthias (November 26, 2015). "IAST: A New Approach For Agile Security Testing". Secodis.
- "OWASP Application Security Verification Standard".