We covered an introduction to security operations center and how it works, what are the different roles, responsibilities such as network monitoring and intrusion detection, incident response and vulnerability management. This was part of TryHackMe Introduction to Cybersecurity track.

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Security Operations Center (SOC) is a team of IT security professionals tasked with monitoring a company’s network and systems 24 hours a day, seven days a week. Their purpose of monitoring is to:

    • Find vulnerabilities on the network: A vulnerability is a weakness that an attacker can exploit to carry out things beyond their permission level. A vulnerability might be discovered in any device’s software (operating system and programs) on the network, such as a server or a computer. For instance, the SOC might discover a set of MS Windows computers that must be patched against a specific published vulnerability. Strictly speaking, vulnerabilities are not necessarily the SOC’s responsibility; however, unfixed vulnerabilities affect the security level of the entire company.

    • Detect unauthorized activity: Consider the case where an attacker discovered the username and password of one of the employees and used it to log in to the company system. It is crucial to detect this kind of unauthorized activity quickly before it causes any damage. Many clues can help us detect this, such as geographic location.

    • Discover policy violations: A security policy is a set of rules and procedures created to help protect a company against security threats and ensure compliance. What is considered a violation would vary from one company to another; examples include downloading pirated media files and sending confidential company files insecurely.

    • Detect intrusionsIntrusions refer to system and network intrusions. One example scenario would be an attacker successfully exploiting our web application. Another example scenario would be a user visiting a malicious site and getting their computer infected.
  • Support with the incident response: An incident can be an observation, a policy violation, an intrusion attempt, or something more damaging such as a major breach. Responding correctly to a severe incident is not an easy task. The SOC can support the incident response team handle the situation.

Data Sources

The SOC uses many data sources to monitor the network for signs of intrusions and to detect any malicious behaviour. Some of these sources are:

  • Server logs: There are many types of servers on a network, such as a mail server, web server, and domain controller on MS Windows networks. Logs contain information about various activities, such as successful and failed login attempts, among many others. There is a trove of information that can be found in the server logs.
  • DNS activityDNS stands for Domain Name System, and it is the protocol responsible for converting a domain name, such as, to an IP address, such as, among other domain name related queries. One analogy of the DNS query is asking, “How can I reach TryHackMe?” and someone replying with the postal address. In practice, if someone tries to browse, the DNS server has to resolve it and can log the DNS query to monitoring. The SOC can gather information about domain names that internal systems are trying to communicate with by merely inspecting DNS queries.
  • Firewall logs: A firewall is a device that controls network packets entering and leaving the network mainly by letting them through or blocking them. Consequently, firewall logs can reveal much information about what packets passed or tried to pass through the firewall.
  • DHCP logsDHCP stands for Dynamic Host Configuration Protocol, and it is responsible for assigning an IP address to the systems that try to connect to a network. One analogy of the DHCP request would be when you enter a fancy restaurant, and the waiter welcomes you and guides you to an empty table. Know that DHCP has automatically provided your device with the network settings whenever you can join a network without manual configuration. By inspecting DHCP transactions, we can learn about the devices that joined the network.

These are some of the most common data sources; however, many other sources can be used to aid in the network security monitoring and the other tasks of the SOC. A SOC might use a Security Information and Event Management (SIEM) system. The SIEM aggregates the data from the different sources so that the SOC can efficiently correlate the data and respond to attacks.

Challenge Answers

What does NSM stand for?
Add the necessary firewall rules to block the ongoing attack. What is the flag that you have received after successfully stopping the attack?

What does SOC stand for?

How many hours a day does the SOC monitor the network?

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