Linux Access Control and Permissions Quiz

Access Limitation and File Permissions

• Access to sensitive applications can be limited through various methods including user authentication, network security protocols, and application sandboxes.
• In Linux file permissions, the character '-' represents a regular file, while other characters indicate different permission types or directory status.
• The second segment in Linux file permissions indicates the group permissions, dictating what users assigned to that group can do with the file.
• The third segment represents the others' permissions, specifying access levels for all users not in the file's owner or group.
• The last segment of Linux file permissions denotes special permissions, such as setuid, setgid, and sticky bit.

Network Security and MAC Addresses

• Network Access Control Lists (ACLs) can filter access using identifiers such as IP addresses, user roles, or specific applications.
• A Media Access Control (MAC) address uniquely identifies a device on a network, distinct from IP addresses which can change.
• Changing a device's MAC address is not a reliable unique identifier because it can be easily spoofed, leading to security vulnerabilities.
• One disadvantage of using MAC address filtering as a network-oriented ACL is its susceptibility to spoofing, where attackers can impersonate authorized devices.

Applications and Protocols

• Running sensitive applications in sandboxes isolates them from the rest of the system, reducing the risk of exploitation and data leaks.
• The Internet Message Access Protocol (IMAP), which manages emails, operates on port 143, allowing users to access their email accounts.
• The total number of ports available for network communication is 65,536.
• File Transfer Protocol (FTP) utilizes ports 20 and 21 for transferring files between systems.

Security Vulnerabilities and Attacks

• Cross-Site Request Forgery (CSRF) is a type of attack that tricks a user into executing unwanted actions on a different site where they are authenticated.
• Secure Shell (SSH) manages remote connections to systems on port 22, providing a secure channel over an unsecured network.
• Client-side attacks compromise the user's browser or machine, exploiting weaknesses in client applications, such as web browsers.
• Traffic filtering by network port helps to manage and control the types of data that can enter or leave a network, enhancing security.

Code Execution and Email Security

• Malicious code such as JavaScript or other scripts can be sent through web browsers and executed locally, posing security risks.
• In a CSRF attack, embedding a link in a web page or HTML-based email deceptively directs a user to perform actions on a target website without their consent.
• Software vendors increasingly build defensive measures into their software to protect against vulnerabilities and prevent exploitation by malicious entities.