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.

Computer security is and will always be a critical area that affects everyone. Despite all the efforts made to build safer systems and test them, however, new vulnerabilities and vulnerabilities are still emerging and creating the impression of tilting at windmills. Partial justification of the current state, but also possible solutions, brings in many respects an extraordinary view of security through formal language theory. Emphasis should be put on a more responsible approach to the recognition and processing of inputs, which are often the gateway to many attacks. In this paper, we will get acquainted with this trend and its recommendations for development and will then introduce a new method of detecting SQL injection attacks built on its foundations.

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.

Web applications constitute an essential part of our daily lives, providing us access to significant online services and information. Despite their advantages, they are also vulnerable to security threats, particularly SQL injection attacks. SQL injection is a vulnerability that arises when an attacker inserts malicious SQL queries through user input parameters in a web application. This attack can have severe consequences, such as exposing sensitive information. The purpose of this study is to investigate and analyze the security of web applications against SQL injection attacks. This is achieved by examining SQL injection techniques, their impact on security and integrity, as well as the most common protective solutions. The goal of the study is to enhance and improve the security of applications and protect users from potential security risks. To achieve this, a combination of literature study and practical investigations is conducted. A literature review is performed to identify SQL injection techniques, security risks, and the most prevalent protective solutions. Subsequently, these factors are evaluated and analyzed to determine the effectiveness of the techniques using the penetration testing tool SQLmap. The results of the study indicate that the most common and effective attack techniques are Inband SQL injection and Inferential SQL injection. These techniques can have severe implications for users, businesses, and society at large, such as unauthorized access to protected data, data manipulation in databases, and the compromise of confidentiality and data integrity. To safeguard against such attacks, it is crucial to employ defensive coding practices, including the use of prepared statements with parameterized queries and input validation. However, manual implementation remains challenging. A combination of automated prevention techniques and best coding practices should be employed to ensure a reliable database protected against SQL injections, even concerning stored procedures that are difficult to prevent with existing automated prevention techniques. / Webbapplikationer utgör en viktig del av vårt dagliga liv och ger oss tillgång till betydelsefulla onlinetjänster och information. Trots deras fördelar är de också sårbara för säkerhetshot, särskilt SQL-injektionsattacker. SQL-injektion är en sårbarhet som uppstår när en angripare infogar skadliga SQL-frågor genom användarens inmatningsparametrar i en webbapplikation. Attacken medför allvarliga konsekvenser, såsom exponering av känslig information. Syftet med denna studie är att undersöka och analysera säkerheten i webbapplikationer mot SQL-injektionsattacker. Detta genomförs genom att undersöka SQL-injektionstekniker, deras påverkan på säkerhet och integritet, samt de vanligaste skyddslösningarna. Målet med studien är att öka och förbättra säkerheten hos applikationer samt skydda användarna från potentiella säkerhetsrisker. För att åstadkomma detta genomförs en kombination av litteraturstudier och praktiska undersökningar. En litteraturstudie genomförs för att identifiera SQL-injektionstekniker, säkerhetsrisker och de vanligast förekommande skyddslösningarna. Därefter utvärderas och analyseras dessa faktorer för att kunna fastställa effektiviteten hos teknikerna genom användning av penetrationstestningsverktyget SQLmap. Resultaten av studien visar att de vanligaste och mest effektiva attackteknikerna är Inband SQL-injektion och Inferential SQL-injektion. Dessa tekniker kan få allvarliga konsekvenser för användare, företag och samhället i stort, såsom åtkomst till skyddade data, manipulering av data i databasen och förlust av sekretess och dataintegritet. För att skydda mot sådana attacker är det avgörande att använda defensiva kodningsmetoder, inklusive användning av förberedda satser med parametriserade frågor och indatavalidering. Trots detta utgör manuell implementering en utmaning. En kombination av automatiserade förebyggande tekniker och bästa kod-praxis bör användas för att säkerställa en pålitlig databas som är skyddade mot SQL-injektioner, även när det gäller lagrade procedurer som är svåra att förhindra med befintliga automatiserade förebyggande tekniker.

隨著國內法令規範對於隱私政策更加重視，國內外企業組織因應鉅額罰款與政策的施行，再加上個人資料外洩事件頻傳，各企業無不擔心客戶資料的保護與落實內部資料控制。而大型政府機關或企業，由於服務範圍廣大，應用系統繁多，針對資料外洩的保護與落實，將更加的複雜。大部份的組織針對實體文件、安全性儲存設備管制、使用採購防火牆設備等，皆有進行相關的管理與設備的採購，但上述機制未能解決應用系統的資料外洩問題。對稽核人員而言稽查應用程式是否有資料外洩之虞，由應用程式原始程式碼相當實為不易，而新制定一套更安全存取控管的介面更需投入相當高的成本與時間。 / 本研究在設計與實作資料外洩稽核工具，參考國際標準ISO27002與ISO 13569資訊安全作法，摘選出應用系統資訊安全指引，並根據實務經驗與金融產業的系統特性，找出資料外洩存取規則(Rules)。除此之外需搭配資料庫執行指令記錄器(DB Logger)，由大量的資料庫指令紀錄中快速產生稽核報表，藉以協助稽核人員查核資料外洩的線索並督促組織內部問題的改善，以落實內部資料控管政策與外部法令要求。 / The rapid spread of information technologies into every facet of our life results in a surge in attention to privacy recently. Bills are enacted and a comprehensive privacy policy becomes a sign of a responsible corporation. However, the complexity and diversity of application systems of information makes it very difficult to ensure that the information systems conform to all the privacy regulations and polices. Although most corporations have established some privacy policies for controlling physical documents and various hardware devices, the main problem for data leakage is at application layer. Application developers could retrieve sensitive data by exploiting application flaws. This poses great challenges to information system auditors. Firstly, it is rather difficult for auditors to review the code to spot the flaws. Secondly, it is impractical to make a new coding standard and re-write the legacy applications accordingly. Thirdly, application developers lack the motivation to improve the protection level of existing systems. / This thesis argues that a database audit tool can partly address the above difficulties faced by auditors. Specifically, we design and implement a tool for data leakage auditing. We derive right rules for identifying the potential sources of data leakage by referencing to information security practices such as ISO27002 and ISO 13569, and our practical experience in financial industry. Our tool makes good use of the database logger to produce an audit report based on those rules. The audit reports provide not only useful hints for auditors to detect possible data leakage, but also good evidence for urging developers to enhance their applications for privacy protection.

Today’s massive usage of smartphones has put a high demand on all application developers in the matter of security. For us to be able to keep using all existing and new applications, a process that removes significant security vulnerabilities is essential. To remove these vulnerabilities, the applications have to be tested. In this thesis, we identify six methods for functional and security testing of client-server applications running Android and Python Flask. Regarding functional testing, we implement Espresso testing and RESTful API testing. In regards to the security testing of the system, we do not only implement fuzz testing, sniffing, reverse engineering and SQL injection testing on a system developed by a student group in a parallel project, but also discover a significant security vulnerability that directly affects the integrity and reliability of this system. Out of the six identified testing techniques, reverse engineering exposed the vulnerability. In conjunction with this, we verified that the system’s functionality works as it is supposed to.

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.

Diploma thesis describes published attacks on computers and computer networks. Principles of footprinting such as availability check, OS detection, port scanning were described. Next part explains attacks on confidentiality, integrity and availability. In the practical part were created four laboratory tasks and a virtual environment which allowed testing of ARP spoofing, DNS spoofing, SSL strip, Cross-site scripting, SQL injection, flooding attacks (TCP, ICMP, UDP), TCP reset and attack on operating system using backdoor with Metasploit framework. In practical part were also created video samples with attacks and documentation for teachers.

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.