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Cyber Kill Chain

May 10, 202412 min read

Task 1: Intro

The term kill chain is a military concept related to the structure of an attack. It consists of target identification, decision and order to attack the target, and finally the target destruction.

A Cyber Kill ChainŽ framework defines the steps used by adversaries or malicious actors in cyberspace. To succeed, an adversary needs to go through all phases of the Kill Chain.

We will be exploring the following attack phases in this room:

  • Reconnaissance
  • Weaponization
  • Delivery
  • Exploitation
  • Installation
  • Command & Control
  • Actions on Objectives

Learning Objectives: In this room, you will learn about each phase of the Cyber Kill Chain Framework, the advantages and disadvantages of the traditional Cyber Kill Chain. 

Outcome: As a result, you will be ready to recognize different phases or stages of the attack carried out by an adversary and be able to break the “kill chain.”

Task 2: Reconnaissance

Reconnaissance is discovering and collecting information on the system and the victim. The reconnaissance phase is the planning phase for the adversaries.

OSINT (Open-Source Intelligence) also falls under reconnaissance. OSINT is the first step an attacker needs to complete to carry out the further phases of an attack. The attacker needs to study the victim by collecting every available piece of information on the company and its employees, such as the company’s size, email addresses, phone numbers from publicly available resources to determine the best target for the attack.

More about that here: “What is OSINT?”

Here is a scenario:

A malicious attacker who names himself “Megatron” decides to conduct a very sophisticated attack that he has been planning out for years; he has been studying and researching different tools and techniques that could help him get to the last phase of the Cyber Kill Chain. But first, he needs to start from the Reconnaissance phase.

In order to operate in this phase, the attacker would need to conduct OSINT.  Let’s have a look at Email harvesting.

Email harvesting is the process of obtaining email addressesfrom public, paid, or free services. An attacker can use email-address harvesting for a phishing attack (a type of social-engineering attack used to steal sensitive data, including login credentials and credit card numbers). The attacker will have a big arsenal of tools available for reconnaissance purposes. Here are some of them:

  • theHarvester - other than gathering emails, this tool is also capable of gathering names, subdomains, IPs, and URLs using multiple public data sources 
  • Hunter.io - this is  an email hunting tool that will let you obtain contact information associated with the domain
  • OSINT Framework - OSINT Framework provides the collection of OSINT tools based on various categories

An attacker would also use social media websites such as LinkedIn, Facebook, Twitter, and Instagram to collect information on a specific victim he would want to attack or the company. The information found on social media can be beneficial for an attacker to conduct a phishing attack.

Questions

  1. What is the name of the Intel Gathering Tool that is a web-based interface to the common tools and resources for open-source intelligence?
  1. What is the definition for the email gathering process during the stage of reconnaissance?

Task 3: Weaponization

Deep lore scenario above

After a successful reconnaissance stage, “Megatron” would work on crafting a “weapon of destruction”. He would prefer not to interact with the victim directly and, instead, he will create a “weaponizer” that, according to Lockheed Martin, combines malware and exploit into a deliverable payload.

Most attackers usually use automated tools to generate the malware or refer to the DarkWeb to purchase the malware. More sophisticated actors or nation-sponsored APT (Advanced Persistent Threat Groups) would write their custom malware to make the malware sample unique and evade detection on the target.

Let’s first define some terminology before we analyze the Weaponization phase.

Malware is a program or software that is designed to damage, disrupt, or gain unauthorized access to a computer.

An exploit is a program or a code that takes advantage of the vulnerability or flaw in the application or system.

A payload is a malicious code that the attacker runs on the system.

In the Weaponization phase, the attacker would:

  • Create an infected Microsoft Office document containing a malicious macro or VBA (Visual Basic for Applications) scripts.
  • An attacker can create a malicious payload or a very sophisticated worm, implant it on the USB drives, and then distribute them in public. An example of the virus. 
  • An attacker would choose Command and Control (C2) techniques for executing the commands on the victim’s machine or deliver more payloads.
    • You can read more about the C2 techniques on MITRE ATT&CK.
  • An attacker would select a backdoor implant (the way to access the computer system, which includes bypassing the security mechanisms).

Question

This term is referred to as a group of commands that perform a specific task. You can think of them as subroutines or functions that contain the code that most users use to automate routine tasks. But malicious actors tend to use them for malicious purposes and include them in Microsoft Office documents. Can you provide the term for it?

Task 4: Delivery

The Delivery phase is when “Megatron” decides to choose the method for transmitting the payload or the malware. He has plenty of options to choose from: 

More info you can find in these videos of Messer:

Questions

What is the name of the attack when it is performed against a specific group of people, and the attacker seeks to infect the website that the mentioned group of people is constantly visiting.

Task 5: Exploitation

After gaining access to the system, the malicious actor could exploit software, system, or server-based vulnerabilities to escalate the privileges or move laterally through the network.

According to CrowdStrike, lateral movement refers to the techniques that a malicious actor uses after gaining initial access to the victim’s machine to move deeper into a network to obtain sensitive data. 

If you want to learn more about server-based or web-based vulnerabilities, please refer to the TryHackMe room OWASP Top 10.

The attacker might also apply a “Zero-day Exploit” in this stage.

According to FireEye

”the zero-day exploit or a zero-day vulnerability is an unknown exploit in the wild that exposes a vulnerability in software or hardware and can create complicated problems well before anyone realizes something is wrong. A zero-day exploit leaves NO opportunity for detection at the beginning.”

These are examples of how an attacker carries out exploitation:

  • The victim triggers the exploit by opening the email attachment or clicking on a malicious link.
  • Using a zero-day exploit.
  • Exploit software, hardware, or even human vulnerabilities. 
  • An attacker triggers the exploit for server-based vulnerabilities.

Questions

Can you provide the name for a cyberattack targeting a software vulnerability that is unknown to the antivirus or software vendors?

Task 6: Installation

Once the attacker gets access to the system, he would want to reaccess the system if he loses the connection to it or if he got detected and got the initial access removed, or if the system is later patched. That is when the attacker needs to install a persistent backdoor.

A persistent backdoor will let the attacker access the system he compromised in the past. You can check out the Windows Persistence Room on TryHackMe to learn how an attacker can achieve persistence on Windows. 

The persistence can be achieved through:

  • Installing a web shell on the webserver. A web shell is a malicious script written in web development programming languages such as ASP, PHP, or JSP used by an attacker to maintain access to the compromised system. Because of the web shell simplicity and file formatting (.php, .asp, .aspx, .jsp, etc.) can be difficult to detect and might be classified as benign. You may check out this great article released by Microsoft on various web shell attacks.
  • Installing a backdoor on the victim’s machine. For example, the attacker can use Meterpreter to install a backdoor on the victim’s machine. Meterpreter is a Metasploit Framework payload that gives an interactive shell from which an attacker can interact with the victim’s machine remotely and execute the malicious code.
  • Creating or modifying Windows services. This technique is known as T1543.003 on MITRE ATT&CK (MITRE ATT&CKÂŽ is a knowledge base of adversary tactics and techniques based on real-world scenarios). An attacker can create or modify the Windows services to execute the malicious scripts or payloads regularly as a part of the persistence. An attacker can use the tools like sc.exe (sc.exe lets you Create, Start, Stop, Query, or Delete any Windows Service) and Reg to modify service configurations. The attacker can also masquerade the malicious payload by using a service name that is known to be related to the Operating System or legitimate software. 
  • Adding the entry to the “run keys” for the malicious payload in the Registry or the Startup Folder. By doing that, the payload will execute each time the user logs in on the computer. According to MITRE ATT&CK, there is a startup folder location for individual user accounts and a system-wide startup folder that will be checked no matter what user account logs in.

You can read more about the Registry Run Keys / Startup Folder persistence on one of the MITRE ATT&CK techniques.

In this phase, the attacker can also use the Timestomping technique to avoid detection by the forensic investigator and also to make the malware appear as a part of a legitimate program. The Timestomping technique lets an attacker modify the file’s timestamps, including the modify, access, create and change times.

Questions

  1. Can you provide the technique used to modify file time attributes to hide new or changes to existing files?
  1. Can you name the malicious script planted by an attacker on the webserver to maintain access to the compromised system and enables the webserver to be accessed remotely?

Task 7: C2 - Command and Control

Also known as C&C or C2 Beaconing as a type of malicious communication between a C&C server and malware on the infected host. The infected host will consistently communicate with the C2 server; that is also where the beaconing term came from.

The compromised endpoint would communicate with an external server set up by an attacker to establish a command & control channel. After establishing the connection,  the attacker has full control of the victim’s machine. Until recently, IRC (Internet Relay Chat) was the traditional C2 channel used by attackers. This is no longer the case, as modern security solutions can easily detect malicious IRC traffic. 

The most common C2 channels used by adversaries nowadays:

  • HTTP on port 80 and HTTPS on port 443 - this type of beaconing blends the malicious traffic with the legitimate traffic and can help the attacker evade firewalls.  
  • DNS - The infected machine makes constant DNS requests to the DNS server that belongs to an attacker, this type of C2 communication is also known as DNS Tunneling.

Important to note that an adversary or another compromised host can be the owner of the C2 infrastructure.

Questions

What is the C2 communication where the victim makes regular DNS requests to a DNS server and domain which belong to an attacker.

Task 8: Actions on Objectives (Exfiltration)

After going through six phases of the attack, “Megatron” can finally achieve his goals (deepest lore lmao), which means taking action on the original objectives. With hands-on keyboard access, the attacker can achieve the following: 

  • Collect the credentials from users.
  • Perform privilege escalation (gaining elevated access like domain administrator access from a workstation by exploiting the misconfiguration).
  • Internal reconnaissance (for example, an attacker gets to interact with internal software to find its vulnerabilities).
  • Lateral movement through the company’s environment.
  • Collect and exfiltrate sensitive data.
  • Deleting the backups and shadow copies. Shadow Copy is a Microsoft technology that can create backup copies, snapshots of computer files, or volumes. 
  • Overwrite or corrupt data.

Questions

Can you provide a technology included in Microsoft Windows that can create backup copies or snapshots of files or volumes on the computer, even when they are in use?

Task 9: Practical

Here is the real-world scenario for you to tackle: On December 19th, 2013, Target released a statement confirming the breach, stating that approximately 40 million credit and debit card accounts were impacted between Nov. 27 and Dec. 15, 2013. Target had to pay the fine of $18.5 million under the terms of the multistate settlement agreement. This is considered to be the largest data-breach settlement in history.

How did the data breach happen? Deploy the static site attached to this task and apply your skills to build the Cyber Kill Chain of this scenario. Here are some tips to help you complete the practical:

1. Add each item on the list in the correct Kill Chain entry-form on the Static Site Lab:

  • exploit public-facing application
  • data from local system
  • powershell
  • dynamic linker hijacking
  • spearphishing attachment
  • fallback channels

2. Use the ‘Check answers’ button to verify whether the answers are correct (where wrong answers will be underlined in red).

Questions

I can give you the flag but that’s no way to do the lab, go do it lmao

In case you just want answer:

Conclusion

Cyber Kill Chain can be a great tool to improve network defence. Is it perfect and can it be the only tool to rely on? No.

But the cybersecurity threats have developed drastically nowadays, and adversaries are combining multiple TTP (tactics, techniques, and procedures) to achieve their goal.

Adversaries are capable of defeating threat intelligence by modifying the file hashes and IP addresses. Security solutions companies are developing technologies like AI (Artificial Intelligence) and different algorithms to detect even slight and suspicious changes.

We (as in TryHackMe people) recommend not only relying on the traditional Cyber Kill Chain model but also referring to MITRE ATT&CK as well as Unified Kill Chain to apply a more comprehensive approach to your defence methodologies.

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