Incident management is a process that aims to handle a control failure that leads to a breach by restoring normal operations as quickly as possible and minimizing the impact and damage of the incident. Incident management involves activities such as identifying, analyzing, containing, eradicating, recovering, and learning from security incidents. Risk assessment, root cause analysis, and vulnerability management are other processes related to security management, but they are not designed to handle a control failure that leads to a breach. Reference: https://www.sans.org/reading-room/whitepapers/incident/incident-handlers-handbook-33901

User access logging (UAL) is a feature on Windows Server operating systems that records the details of remote access and management activities performed by users on the server. UAL can provide information such as the user name, the source IP address, the destination host name, the protocol used, and the time and duration of the connection1. Enabling user access logging on the VPN server can help the security analyst to obtain the best information to identify and investigate the inbound connection originating from an unknown IP address.

A) The analyst should disable DNS recursion is not correct. DNS recursion is a process where a DNS server queries other DNS servers on behalf of a client until it finds the authoritative answer for a domain name2. Disabling DNS recursion would prevent the DNS server from resolving any domain names that are not in its cache or zone files, which would affect the normal functionality of the network and the internet access of the clients.
C) The analyst should disconnect host 192.168.1.67 is not correct. Disconnecting host 192.168.1.67 would stop the communication with the malicious domain, but it would also disrupt the legitimate activities of the host and its user. Moreover, disconnecting the host would not remove the malware or root cause of the compromise, and it would not prevent the host from reconnecting to the malicious domain once it is online again.
D) The analyst should sinkhole 102.100.20.20 is not correct. Sinkholing is a technique that redirects malicious or unwanted traffic to a controlled destination, such as a fake or isolated server3. Sinkholing 102.100.20.20 would prevent the communication with the malicious domain, but it would also require access and control over the public resolver 8.8.8.8, which is not owned or managed by the analyst or the company.
E) The analyst should disallow queries to the 8.8.8.8 resolver is not correct. Disallowing queries to the 8.8.8.8 resolver would prevent the communication with the malicious domain, but it would also affect the resolution of other legitimate domain names that are not in the local DNS server's cache or zone files.
1: DNS Tunneling: how DNS can be (ab)used by malicious actors 2: What Is DNS Recursion? 3: What Is a Sinkhole Attack?
Explanation:
The correct answer is B. The analyst should block requests to no-thanks.invalid. The log snippet shows a DNS query from host 192.168.1.67 to the public resolver 8.8.8.8 for the domain name no-thanks.invalid, which is resolved to the IP address 102.100.20.20. This is a possible indicator of compromise (IOC), as no-thanks.invalid is a known malicious domain that is used by attackers to exfiltrate data or execute commands on compromised hosts1. The analyst should block requests to this domain to prevent further communication with the attacker's server and investigate the host 192.168.1.67 for signs of infection.

The Diamond Model of Intrusion Analysis is a framework for analyzing and understanding malicious activity on a system or network. It defines the basic atomic element of any intrusion activity as the event, which consists of four core features: adversary, infrastructure, capability, and victim. These features are connected by edges that represent their underlying relationships and arranged in the shape of a diamond1 The infrastructure feature refers to the physical or logical communication structures that are used by the adversary to deliver a capability or interact with a victim. Examples of infrastructure elements are IP addresses, domain names, email addresses, servers, routers, etc. The domain, IP address, email address, and software version that the analyst extracted from the artifacts are all examples of infrastructure elements that can be used to identify or track the adversary's activity.

The security incident response process is a set of procedures and guidelines that define how to identify, contain, analyze, and recover from security incidents that compromise the confidentiality, integrity, or availability of an organization's assets or operations. Initiating the security incident response process for unauthorized access is the first and most appropriate action that the analyst should take, as it would allow the analyst to follow a structured and consistent approach to handle the situation and mitigate the impact of the incident1.