This dissertation generalizes traditional models of security policies, from specifications of whether programs are secure, to specifications of how secure programs are. This is a generalization from qualitative, black-and-white policies to quantitative, gray policies. Included are generalizations from traditional definitions of safety and liveness policies to definitions of gray-safety and gray-liveness policies. These generalizations preserve key properties of safety and liveness, including that the intersection of safety and liveness is a unique allow-all policy and that every policy can be written as the conjunction of a single safety and a single liveness policy. It is argued that the generalization provides several benefits, including that it serves as a unifying framework for disparate approaches to security metrics, and that it separates—in a practically useful way—specifications of how secure systems are from specifications of how secure users require their systems to be. To demonstrate the usefulness of the new model, policies for mitigating injection attacks (including both code- and noncode-injection attacks) are explored. These policies are based on novel techniques for detecting injection attacks that avoid many of the problems associated with existing mechanisms for preventing injection attacks.

The battle for cyber supremacy is a cat and mouse game: evolving threats from internal and external sources make it difficult to protect critical systems. With the diverse and high risk nature of these threats, there is a need for robust techniques that can quickly adapt and address this evolution. Existing tools such as Splunk, Snort, and Bro help IT administrators defend their networks by actively parsing through network traffic or system log data. These tools have been thoroughly developed and have proven to be a formidable defense against many cyberattacks. However, they are vulnerable to zero-day attacks, slow attacks, and attacks that originate from within. Should an attacker or some form of malware make it through these barriers and onto a system, the next layer of defense lies on the host. Host level defenses include system integrity verifiers, virus scanners, and event log parsers. Many of these tools work by seeking specific attack signatures or looking for anomalous events. The defenses at the network and host level are similar in nature. First, sensors collect data from the security domain. Second, the data is processed, and third, a response is crafted based on the processing. The application level security domain lacks this three step process. Application level defenses focus on secure coding practices and vulnerability patching, which is ineffective. The work presented in this thesis uses a technique that is commonly employed by malware, dynamic-link library (DLL) injection, to develop dynamic application level security sensors that can extract fine-grain data at runtime. This data can then be processed to provide stronger application level defense by shrinking the vulnerability window. Chapters 5 and 6 give proof of concept sensors and describe the process of developing the sensors in detail.

The battle for cyber supremacy is a cat and mouse game: evolving threats from internal and external sources make it difficult to protect critical systems. With the diverse and high risk nature of these threats, there is a need for robust techniques that can quickly adapt and address this evolution. Existing tools such as Splunk, Snort, and Bro help IT administrators defend their networks by actively parsing through network traffic or system log data. These tools have been thoroughly developed and have proven to be a formidable defense against many cyberattacks. However, they are vulnerable to zero-day attacks, slow attacks, and attacks that originate from within. Should an attacker or some form of malware make it through these barriers and onto a system, the next layer of defense lies on the host. Host level defenses include system integrity verifiers, virus scanners, and event log parsers. Many of these tools work by seeking specific attack signatures or looking for anomalous events. The defenses at the network and host level are similar in nature. First, sensors collect data from the security domain. Second, the data is processed, and third, a response is crafted based on the processing. The application level security domain lacks this three step process. Application level defenses focus on secure coding practices and vulnerability patching, which is ineffective. The work presented in this thesis uses a technique that is commonly employed by malware, dynamic-link library (DLL) injection, to develop dynamic application level security sensors that can extract fine-grain data at runtime. This data can then be processed to provide stronger application level defense by shrinking the vulnerability window. Chapters 5 and 6 give proof of concept sensors and describe the process of developing the sensors in detail.

Buffer overflow vulnerabilities continue to prevail and the sophistication of attacks targeting these vulnerabilities is continuously increasing. As a successful attack of this type has the potential to completely compromise the integrity of the targeted host, early detection is vital. This thesis examines generic approaches for detecting executable payload attacks, without prior knowledge of the implementation of the attack, in such a way that new and previously unseen attacks are detectable. Executable payloads are analysed in detail for attacks targeting the Linux and Windows operating systems executing on an Intel IA-32 architecture. The execution flow of attack payloads are analysed and a generic model of execution is examined. A novel classification scheme for executable attack payloads is presented which allows for characterisation of executable payloads and facilitates vulnerability and threat assessments, and intrusion detection capability assessments for intrusion detection systems. An intrusion detection capability assessment may be utilised to determine whether or not a deployed system is able to detect a specific attack and to identify requirements for intrusion detection functionality for the development of new detection methods. Two novel detection methods are presented capable of detecting new and previously unseen executable attack payloads. The detection methods are capable of identifying and enumerating the executable payload’s interactions with the operating system on the targeted host at the time of compromise. The detection methods are further validated using real world data including executable payload attacks.

SQL injection is a technique directed against web applications using an SQL database, which can pose a huge security risk. It involves inserting code into an SQL database, and this attack exploits vulnerabilities in the database or application layer. The main goal of my thesis is to get acquainted with the essence of SQL injection, to understand the various methods of this attack technique and to show ways to defend against it. The work can be divided into these main parts, which I will discuss as follows.In the introductory part of the work I mention the theoretical basis concerning SQL injection issues. The next chapter is focused on individual methods of this technique. The analytical part is devoted to mapping the current state of test subjects, scanning tools, which form the basis for optimal research and testing of individual SQL methods, which are discussed in this part from a practical point of view along with the analysis of commands. In the last part I will implement SQL methods on selected subjects and based on the outputs I will create a universal design solution how to defend against such attacks.

As the use of web applications is increasing among a number of different industries, many companies turn to online applications to promote their services. Companies see the great advantages with web applications such as convenience, low costs and little need of additional hardware or software configuration. Meanwhile, the threats against web applications are scaling up where the attacker is not in need of much experience or knowledge to hack a poorly secured web application as the service easily can be accessed over the Internet. While common attacks such as cross-site scripting and SQL injection are still around and very much in use since a number of years, the hacker community constantly discovers new exploits making businesses in need of higher security. Penetration testing is a method used to estimate the security of a computer system, network or web application. The aim is to reveal possible vulnerabilities that could be exploited by a malicious attacker and suggest solutions to the given problem at hand. With the right security fixes, a business system can go from being a threat to its users’ sensitive data to a secure and functional platform with just a few adjustments. This thesis aims to help the IT security consultants at Combitech AB with detecting and securing the most common web application exploits that companies suffer from today. By providing Combitech with safe and easy methods to discover and fix the top security deficiencies, the restricted time spent at a client due to budget concerns can be made more efficient thanks to improvements in the internal testing methodology. The project can additionally be of interest to teachers, students and developers who want to know more about web application testing and security as well as common exploit scenarios.