Web applications are a crucial aspect of business in today's digital savvy world. Their functionality and versatility make them an appealing target for attackers, thereby necessitating robust security measures. 'Application security testing' is one such measure, ensuring that web applications are safe from threats. This role has become even more relevant with the emergence of the OWASP (Open Web Application Security Project) Top Ten, a document outlining the most serious security risks to web applications. To appreciate the full importance of Application security testing, it's beneficial to understand these risks.

A1:2017-Injection

Injection flaws occur when untrusted data is sent to an interpreter as part of a command. The attacker can use this to trick the interpreter and make it perform unintended commands. Injection flaws can be prevented by keeping data separate from commands and queries.

A2:2017-Broken Authentication

Application functions related to authentication and session management are often implemented incorrectly, enabling hackers to compromise passwords, keys, session cookies, etc. Multifactor authentication, restricting failed login attempts, and using authentication frameworks can aid in mitigating broken authentications.

A3:2017-Sensitive Data Exposure

Many web applications improperly protect sensitive data like tax IDs, credentials, and personal information. Attackers can steal or modify such weakly protected data. Employing encryption, ensuring proper key management, and disabling caching for responses can protect against sensitive data exposure.

A4:2017-XML External Entity (XXE)

Old or poorly configured XML processors evaluate XML External Entity references within XML documents. By exploiting this, attackers can disclose internal files, conduct internal port scanning, perform remote code execution, and instigate DoS attacks. Safeguards include patching XML processors and libraries, disabling XML external entity and DTD processing in all XML parsers in the application or check the incoming XML and reject any weird looking values.

A5:2017-Broken Access Control

Restrictions on authenticated users frequently aren't properly enforced. Attackers can exploit these flaws to access unauthorized functionality and/or data, such as accessing other users' accounts, viewing sensitive files, etc. Effective control measures should be in place, like denying access by default and enforcing access controls at the server-side.

A6:2017-Security Misconfigurations

Security misconfigurations can occur at any level of an application stack. This includes cloud storage, database, application server, platform, framework, etc. These misconfigurations can offer unauthorized access to information and functionalities. To avoid this, a least privilege basis should be applied, unnecessary features should be disabled, and a systematic configuration change management should be followed.

A7:2017-Cross-Site Scripting (XSS)

XSS flaws occur when an application includes untrusted data in a new web page without proper validation or escaping. XSS enables attackers to execute scripts in the victim's browser to hijack user sessions, deface web sites, or redirect the user to malicious sites. Encoding untrusted HTTP request data can prevent this.

A8:2017-Insecure Deserialization

Insecure deserialization often leads to remote execution. Even without code execution, leaked details can be used to replay attacks. Implementing integrity checks such as digital signatures on serialized objects can prevent insecure deserialization.

A9:2017-Using Components with Known Vulnerabilities

Applications and APIs using components with known vulnerabilities open the door to attacks, as they undermine application defenses. It is good practice to remove unused components and ensure components are up to date.

A10:2017-Insufficient Logging & Monitoring

Insufficient logging and monitoring, coupled with missing or ineffective integration with Incident response, enables attackers to continue their attack. Adequate logging, monitoring, and response planning can help identify and stop threats in real time.

Conclusion

In conclusion, the OWASP Top Ten highlights critical security risks faced by web applications. Understanding these risks plays a pivotal role in Application security testing, enabling us to develop robust mechanisms to combat these threats. By staying abreast of these risks, we can ensure web application security, thereby safeguarding users' data and enhancing our systems' resilience against attacks.