Network Attacks

A network attack refers to deliberate efforts targeting the security of computer systems with the aim of compromising the principles of confidentiality, integrity, and availability. These principles are defined in information security literature as the “CIA triangle” and represent the fundamental components that systems must protect. Network attacks are typically carried out using methods aimed at gaining unauthorized access, stealing data, disrupting services, or damaging systems. Such attacks not only harm digital data but can also lead to financial losses, service interruptions, and in some cases, physical security vulnerabilities. As network technologies evolve, threats become increasingly complex, necessitating greater sensitivity and scope in detection systems. Anomaly-based Intrusion Detection Systems (Anomaly-based IDS), developed to ensure network security, play an effective role in identifying violations where attackers mimic legitimate system behavior. These systems aim to provide more proactive protection by detecting not only known threats but also abnormal behaviors.

Denial of Service (DoS/DDoS) Attacks

Denial of Service attacks are threats designed to disrupt service provision by exhausting the target system’s resources. DoS attacks are generally launched from a single source, while DDoS attacks involve simultaneous execution from multiple devices. DDoS attacks overwhelm systems with heavy traffic loads, causing resource depletion and rendering systems inoperable or inaccessible. Systems requiring high availability, such as financial institutions, healthcare systems, and public portals, are among the primary targets of these attacks. During such attacks, requests directed to the server often contain invalid or incomplete information, leading to the wasteful consumption of processing resources. To effectively counter high-impact DDoS attacks, firewalls, load balancers, and behavioral analysis systems must be used in combination. Anomaly-based detection mechanisms enable early identification of such attacks; however, due to their distributed nature, pinpointing the origin of the attack is often difficult.

Information Gathering (Probe) Attacks

Information gathering attacks are attempts to collect information about a system’s structure rather than directly damaging it. These attacks commonly involve IP scanning, port analysis, and vulnerability scanning. The objective is to identify open ports and weak points in the system to lay the groundwork for subsequent direct attacks. The success rate of such attacks is particularly high in systems that are poorly configured or inadequately updated. Information gathering attacks must not be overlooked, as they often constitute the first step in more complex attacks. Anomaly detection systems are capable of identifying these attacks in advance by recognizing unusual patterns in network traffic. Machine learning-enabled systems are especially effective in detecting out-of-normal activities through statistical anomaly analysis.

User-to-Root (U2R) Attacks

U2R attacks involve a user with low-level privileges attempting to gain full administrative control over a system. When successfully executed, these attacks grant the attacker the ability to perform any operation within the system. Possible consequences include modification of critical configuration files, theft of sensitive data, and installation of persistent malware. These attacks are commonly carried out using brute force, buffer overflow, or exploitation of system vulnerabilities. Due to their threat to both confidentiality and system integrity, U2R attacks are considered high-risk. Traditional detection systems may struggle to identify these attacks because they often involve low-volume traffic. Consequently, more advanced, cost-sensitive access control models are preferred, and detection sensitivity is enhanced through behavioral analysis.

Remote-to-Local (R2L) Attacks

R2L attacks involve an external attacker attempting to gain access to a system with the privileges of an internal user. These attacks are typically executed through password guessing, phishing, or exploitation of system vulnerabilities. The goal may be to obtain information from within the system or to escalate privileges to a higher level. Detecting R2L attacks is challenging because they often generate very low traffic volumes and may be overlooked by traditional security systems. However, anomaly detection systems can identify abnormal behavior by modeling normal user activities as a baseline. Advanced detection systems can provide more effective protection against such threats through multi-factor authentication, strong password policies, and behavior-based monitoring.