Security-Enhanced Linux Research Articles

Basic Security Mechanisms in Linux

The article provides an overview of the key security aspects of the Linux operating system. The relevance of this work lies in the fact that in light of the rapid development of technology and increased threats in the field of information security, special attention is paid to mechanisms that ensure stable protection of data and system resources. The article begins by reviewing basic security principles such as the principle of least privilege and need-based access. Next, we look at modern authentication and authorization mechanisms, including the role of Pluggable Authentication Modules (PAM) and Security-Enhanced Linux (SELinux) multi-user rules. Particular attention is paid to access control systems, including mechanisms for managing access rights to files through the Discretionary Access Control (DAC) and Mandatory Access Control (MAC). The iptables and firewalld firewalls are analyzed as key tools for ensuring the security of network interactions. The article also covers current Linux security trends and challenges, as well as an overview of the latest kernel and software updates. Ultimately, the reader will gain a comprehensive understanding of Linux security mechanisms, allowing him to make informed decisions to effectively protect his systems and data.

Additional kernel observer: privilege escalation attack prevention mechanism focusing on system call privilege changes

Cyberattacks, especially attacks that exploit operating system vulnerabilities, have been increasing in recent years. In particular, if administrator privileges are acquired by an attacker through a privilege escalation attack, the attacker can operate the entire system and cause serious damage. In this paper, we propose an additional kernel observer (AKO) that prevents privilege escalation attacks that exploit operating system vulnerabilities. We focus on the fact that a process privilege can be changed only by specific system calls. AKO monitors privilege information changes during system call processing. If AKO detects a privilege change after system call processing, whereby the invoked system call does not originally change the process privilege, AKO regards the change as a privilege escalation attack and applies countermeasures against it. AKO can therefore prevent privilege escalation attacks. Introducing the proposed method in advance can prevent this type of attack by changing any process privilege that was not originally changed in a system call, regardless of the vulnerability type. In this paper, we describe the design and implementation of AKO for Linux x86 64-bit. Moreover, we show that AKO can be expanded to prevent the falsification of various data in the kernel space. Then, we present an expansion example that prevents the invalidation of Security-Enhanced Linux. Finally, our evaluation results show that AKO is effective against privilege escalation attacks, while maintaining low overhead.

Anticipatory active monitoring for safety- and security-critical software

Since formal verification and testing of systems is normally faced with challenges such as state explosion and uncertain execution environments, it is extremely difficult to exhaustively verify and test software during the development phase. Therefore, monitoring has become an indispensable means for finding latent software faults at runtime. Most current monitoring approaches only generate passive monitors, which cannot foresee possible faults and consequently cannot prevent their occurrence. In this paper, we propose an active monitoring approach based on runtime verification. This approach aims to predict possible incoming violations using a monitor that executes anticipatory semantics of temporal logic, and then generates the necessary steering actions according to a partial system model, which steers the system away from paths causing these violations. In this case, the monitor and monitored system make up a discrete feedback control loop. We further investigate the control theory behind active monitoring so that non-blocking controllability can be achieved. The results of applying active monitoring to two cases, a railway crossing control system and security-enhanced Linux (SELinux), show that the method can effectively ensure both safety and security properties at runtime.

Securing Android-Powered Mobile Devices Using SELinux

Google's Android framework incorporates an operating system and software stack for mobile devices. Using a general-purpose operating system such as Linux in mobile devices has advantages but also security risks. Security-Enhanced Linux (SELinux) can help reduce potential damage from a successful attack.

Verifying information flow goals in Security-Enhanced Linux

In this paper, we present a systematic way to determine the information flow security goals achieved by systems running a secure O/S, specifically systems running Security-Enhanced Linux. A formalization of the access control mechanism of the SELinux security server, together with a labeled transition system representing an SELinux configuration, provides our framework. Information flow security goal statements expressed in linear temporal logic provide a clear description of the objectives that SELinux is intended to achieve. We use model checking to determine whether security goals hold in a given system. These formal models combined with appropriate algorithms have led to automated tools for the verification of security properties in an SELinux system. Our approach has been used in other security management contexts over the past decade, under the name rigorous automated security management.

Verifying information flow goals in security-enhanced Linux

In this paper, we present a systematic way to determine the information flow security goals achieved by systems running a secure O/S, specifically systems running Security-Enhanced Linux. A formali...