A runbook is a set of predefined procedures and steps that guide an incident response team through the process of handling a security incident. It can help the blue team respond quickly and effectively to an indicator of compromise (IOC) by following the best practices and predefined actions for containment, eradication, recovery and lessons learned.

Explanation
A single point of failure is a component or element of a system that, if it fails, will cause the entire system to fail or stop functioning. It can pose a high risk and impact for business continuity and availability. A high availability pair is a configuration that involves two identical devices or systems that operate in parallel and provide redundancy and failover capabilities. It can remove the single point of failure by ensuring that if one device or system fails, the other one can take over its functions without interruption or downtime.

Explanation
Network and firewall logs should be analyzed to identify the impacted host in a cybersecurity incident involving a command-and-control server. A command-and-control server is a central server that communicates with and controls malware-infected devices or bots. A command-and-control server can send commands to the bots, such as downloading additional malware, stealing data, or launching attacks. Network logs can help to identify any suspicious or anomalous network traffic, such as connections to unknown or malicious domains, high-volume data transfers, or unusual protocols or ports. Firewall logs can help to identify any blocked or allowed traffic based on the firewall rules, such as connections to or from the command-and-control server, or any attempts to bypass the firewall. References:
https://cybersecurity.att.com/blogs/security-essentials/command-and-control-server-detection-methods-bes
https://www.howtogeek.com/726136/what-is-a-command-and-control-server-for-malware/

Explanation
SQLi stands for SQL injection, which is a type of web security vulnerability that allows an attacker to execute malicious SQL statements on a database server. SQLi can result in data theft, data corruption, denial of service, or remote code execution.
The attacker in the web server log is trying to exploit a SQLi vulnerability by sending a malicious GET request that contains a UNION ALL SELECT statement. This statement is used to combine the results of two or more SELECT queries into a single result set. The attacker is attempting to retrieve user login, user pass, and user email from the wp users table, which is a WordPress database table that stores user information. The attacker may use this information to compromise the WordPress site or the users' accounts.

Explanation
DNS poisoning, also known as DNS spoofing or DNS cache poisoning, is a form of computer security hacking in which corrupt Domain Name System (DNS) data is introduced into the DNS resolver's cache, causing the name server to return an incorrect result record, such as an IP address. This results in traffic being diverted to the attacker's computer (or any other malicious destination).
DNS poisoning can be performed by various methods, such as:
* Intercepting and forging DNS responses from legitimate servers
* Compromising DNS servers and altering their records
* Exploiting vulnerabilities in DNS protocols or implementations
* Sending malicious emails or links that trigger DNS queries with poisoned responses According to CompTIA Security+ SY0-601 Exam Objectives 1.4 Given a scenario, analyze potential indicators to determine the type of attack:
"DNS poisoning, also known as DNS spoofing or DNS cache poisoning, is a form of computer security hacking in which corrupt Domain Name System (DNS) data is introduced into the DNS resolver's cache, causing the name server to return an incorrect result record." References: https://www.comptia.org/certifications/security#examdetails
https://www.comptia.org/content/guides/comptia-security-sy0-601-exam-objectives
https://www.cloudflare.com/learning/dns/dns-cache-poisoning/