Στην παρούσα διπλωματική εργασία παρουσιάζονται βασικές έννοιες και μέθοδοι για την ασφάλεια ιστοσελίδων και ιδιαίτερα των site με web application προσανατολισμό, χωρίς αυτό να σημαίνει ότι αρκετές τεχνικές προστασίας και σφάλματα που θα εντοπίσουμε δεν μπορούν να συναντηθούν και σε άλλου σκοπού ιστοσελίδες. Αρχικά, γίνεται αναφορά στο τι είναι μια εφαρμογή ιστού (web app) και ποια είναι τα στοιχεία που την αποτελούν. Στη συνέχεια, χρησιμοποιώντας έρευνες, παρουσιάζονται κάποιες από τις πιο “δημοφιλείς” επιθέσεις που γίνονται σε ιστοσελίδες και περιγράφεται πιο διεξοδικά ποια αδύνατα σημεία της δομής των ιστοσελίδων εκμεταλλεύονται. Παράλληλα, γίνεται αναφορά στο πως και με ποια εργαλεία μπορούμε να εντοπίσουμε και να κλείσουμε τα κενά ασφαλείας που τυχόν έχει μία εφαρμογή ιστού. Τέλος, παρουσιάζεται η εφαρμογή που αναπτύχθηκε στα πλαίσια της εργασίας με σκοπό να γίνει επίδειξη συγκεκριμένων επιθέσεων και σφαλμάτων που παρατηρούνται στο διαδίκτυο. / In the following pages basic principals and methods are presented in order to secure websites and web applications. I begin by mentioning what is a web application. Moreover, by using statistics and recent researches from various sources i mention the most common web app attack methods and which vulnerabilities can be found in a web app and how to prevent exploiting, something we can accomplish by using various penetration testing tools. Finally, by using a basic web app some web attacks are shown so that it will become more clear how these attacks work.

Most of the people in the industrial world are using several web applications every day. Many of those web applications contain vulnerabilities that can allow attackers to steal sensitive data from the web application's users. One way to detect these vulnerabilities is to have a penetration tester examine the web application. A common way to train penetration testers to find vulnerabilities is to challenge them with realistic web applications that contain vulnerabilities. The penetration tester's assignment is to try to locate and exploit the vulnerabilities in the web application. Training on the same web application twice will not provide any new challenges to the penetration tester, because the penetration tester already knows how to exploit all the vulnerabilities in the web application. Therefore, a vast number of web applications and variants of web applications are needed to train on. This thesis describes a tool designed and developed to automatically generate vulnerable web applications. First a web application is prepared, so that the tool can generate a vulnerable version of the web application. The tool injects Cross Site Scripting (XSS) and Cross Site Request Forgery (CSRF) vulnerabilities in prepared web applications. Different variations of the same vulnerability can also be injected, so that different methods are needed to exploit the vulnerability depending on the variation. A purpose of the tool is that it should generate web applications which shall be used to train penetration testers, and some of the vulnerabilities the tool can inject, cannot be detected by current free web application vulnerability scanners, and would thus need to be detected by a penetration tester. To inject the vulnerabilities, the tool uses abstract syntax trees and taint analysis to detect where vulnerabilities can be injected in the prepared web applications. Tests confirm that web application vulnerability scanners cannot find all the vulnerabilities on the web applications which have been generated by the tool.

Web Application Firewall (WAF) is used to protect the Web application (web app). One of the advantages of having WAF is, it can detect possible attacks even if there is no validation implemented on the web app. But how can WAF protect the web app if WAF itself is vulnerable? In general, four testing methods are used to test WAF such as fuzzing, payload execution, bypassing, and footprinting. There are several open-source WAF testing tools but it appears that it only offers one or two testing methods. That means a tester is required to have multiple tools and learn how each tool works to be able to test WAF using all testing methods. This project aims to solve this difficulty by developing a WAF testing tool called ProjectX that offers all testing methods. ProjectX has been tested on a testing environment and the results show that it fulfilled its requirements. Moreover, ProjectX is available on Github for any developer who want to improve or add more functionality to it.

Both for its simplicity and efficiency to search for the most critical security vulnerabilities that could exist within a web application, a web vulnerability scanner is a popular tool among any company that develops a web application. With the existence of many different scanners that are available to use, one is unlikely the same as the other and the results attained when evaluating these scanners in relation to each other are often not the same. In this thesis, three different open source web vulnerability scanners are evaluated and analysed based on their ability to find SQL injection and cross-site scripting vulnerabilities. The scanners were used on several open source deliberately broken web applications that acted as benchmarks. The benchmarks that caused much diversity in the results from the scanners were further investigated. When analysing the scanners based on the results, both the actual results were analysed on what caused the diversity but most of all the source code of the scanners were explored and investigated. It could be found that the techniques used by the scanners were essentially similar but contained several minor differences that caused the diversity in the results. Most differences were dependant on the variation of the predefined payloads injected by the scanners, but it could also be found that the approaches used to determine if a vulnerability was detected or not could vary as well. The finalised result concluded in a report that reveals and demonstrates the different approaches that any web vulnerability scanner could use and the limitations of them.

There is information to my master's thesis which is called “Web application for NS2 training”. This application works after installation and its source codes are saved on applied CD. It is said about implement Network Simulator 2. It helps to realize simulation of nets and then author inserts information about them into web application. Registered web's visitor has possibility to insert project into application. The project contents information about simulation created in NS2. Web application can also visible detail of possible project which is approved of administrator. Then the visitor can sort projects, search entered expression or connect his contribution to discussion forum. Administrator can approve users projects in his part of application. It makes available for the others. He can also delete them from database. Theory about technologies which are used for implementation of this application. It is talked about web Apache server, database MySQL server and programmable PHP language. There is also mentioned information about security of web application included possible attacks on applications and their database. It is presented proposal of database which creates core of application. This proposal is depended on application requirements. Next chapters give to reader whole image about functionality of application. There are mentioned samples of final graphical image of application. This document also provides the shows of source codes for creating database tables.

Today’s society is highly dependent on functional and secure digital resources, to protect users and to deliver different kinds of services. To achieve this, it is important to evaluate the security of such resources, to find vulnerabilities and handle them before they are exploited. This study aimed to see if web applications based on C#, .NET and Episerver had vulnerabilities, by performing different penetration tests and a security audit. The penetration tests utilized were SQL injection, Cross Site Scripting, HTTP request tampering and Directory Traversal attacks. These attacks were performed using Kali Linux and the Burp Suite tool on a specific web application. The results showed that the web application could withstand the penetration tests without disclosing any personal or sensitive information. However, the web application returned many different types of HTTP error status codes, which could potentially reveal areas of interest to a hacker. Furthermore, the security audit showed that it was possible to access the admin page of the web application with nothing more than a username and password. It was also found that having access to the URL of a user’s invoice file was all that was needed to access it. / Dagens samhälle är starkt beroende av funktionella och säkra digitala resurser, för att skydda användare och för att leverera olika typer av tjänster. För att uppnå detta är det viktigt att utvärdera säkerheten för sådana resurser för att hitta sårbarheter och hantera dem innan de utnyttjas. Denna studie syftar till att se om webapplikationer baserade på C#, .NET och Episerver har sårbarheter, genom att utföra olika penetrationstester och genom att göra en säkerhetsgranskning. Penetrationstesterna som användes var SQL-injektion, Cross Site Scripting, HTTP-förfrågningsmanipulering och Directory Traversal-attacker. Dessa attacker utfördes med Kali Linux och Burp Suite-verktygen på en specifik webbapplikation. Resultaten visade att webbapplikationen klarade penetrationstesterna utan att avslöja någon personlig eller känslig information. Webbapplikationen returnerade dock många olika typer av HTTP-felstatuskoder, som potentiellt kan avslöja områden av intresse för en hackare. Vidare visade säkerhetsgranskningen att det var möjligt att komma åt webbapplikationens adminsida med inget annat än ett användarnamn och lösenord. Det visade sig också att allt som behövdes för att komma åt en användares fakturafiler var webbadressen.