The Cyber Kill Chain framework is designed for identification and prevention of the network intrusions. You will learn what the adversaries need to do in order to achieve their goals.
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.
Thanks to Lockheed Martin, a global security and aerospace company, that established the Cyber Kill Chain® framework for the cybersecurity industry in 2011 based on the military concept. The 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 go through the attack phases and help you better understand adversaries and their techniques used in the attack to defend yourself.
So, why is it important to understand how Cyber Kill Chain works?
The Cyber Kill Chain will help you understand and protect against ransomware attacks, security breaches as well as Advanced Persistent Threats (APTs). You can use the Cyber Kill Chain to assess your network and system security by identifying missing security controls and closing certain security gaps based on your company’s infrastructure.
By understanding the Kill Chain as a SOC Analyst, Security Researcher, Threat Hunter, or Incident Responder, you will be able to recognize the intrusion attempts and understand the intruder’s goals and objectives.
We will be exploring the following attack phases in this room:
- Command & Control
- Actions on Objectives
To learn what reconnaissance is from the attacker’s perspective, first, let’s define the term 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.
You can also find out more about OSINT from this Varonis article, “What is OSINT?”
Let’s look at it from the attacker’s perspective, who initially doesn’t know what company he wants to attack.
Here is the 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.
What is the definition for the email gathering process during the stage of reconnaissance?
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.
Continuing with our adversary, “Megatron” chooses…
“Megatron” chooses to buy an already written payload from someone else in the DarkWeb, so that he can spend more time on the other phases.
In the Weaponization phase, the attacker would:
- Create an infected Microsoft Office document containing a malicious macro or VBA (Visual Basic for Applications) scripts. If you want to learn about macro and VBA, please refer to the article “Intro to Macros and VBA For Script Kiddies” by TrustedSec.
- 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).
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:
- Phishing email: after conducting the reconnaissance and determining the targets for the attack, the malicious actor would craft a malicious email that would target either a specific person (spearphishing attack) or multiple people in the company. The email would contain a payload or malware. For example, “Megatron” would learn that Nancy from the Sales department at company A would constantly like the posts on LinkedIn from Scott, a Service Delivery Manager at company B. He would give it a second guess that they both communicate with each other over work emails. “Megatron” would craft an email using Scott’s First Name and Last Name, making the domain look similar to the company Scott is working at. An attacker would then send a fake “Invoice” email to Nancy, which contains the payload.
- Distributing infected USB drives in public places like coffee shops, parking lots, or on the street. An attacker might decide to conduct a sophisticated USB Drop Attack by printing the company’s logo on the USB drives and mailing them to the company while pretending to be a customer sending the USB devices as a gift. You can read about one of these similar attacks at CSO Online “Cybercriminal group mails malicious USB dongles to targeted companies.”
- Watering hole attack. A watering hole attack is a targeted attack designed to aim at a specific group of people by compromising the website they are usually visiting and then redirecting them to the malicious website of an attacker’s choice. The attacker would look for a known vulnerability for the website and try to exploit it. The attacker would encourage the victims to visit the website by sending “harmless” emails pointing out the malicious URL to make the attack work more efficiently. After visiting the website, the victim would unintentionally download malware or a malicious application to their computer. This type of attack is called a drive-by download. An example can be a malicious pop-up asking to download a fake Browser extension.
To gain access to the system, an attacker needs to exploit the vulnerability. In this phase, “Megatron” got a little bit creative – he created two phishing emails, one that contains a phishing link to a fake Office 365 login page and another one containing a macro attachment that would execute ransomware when the victim opens it. “Megatron” successfully delivered his exploits and got two victims to click on the malicious link and open the malicious file.
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.
As you have learned from the Weaponization phase, the backdoor lets an attacker bypass security measures and hide the access. A backdoor is also known as an access point.
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. He will no longer have access to it. 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&CK® 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.
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?
After getting persistence and executing the malware on the victim’s machine, “Megatron” opens up the C2 (Command and Control) channel through the malware to remotely control and manipulate the victim. This term is 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:
- The protocols 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 (Domain Name Server). 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.
After going through six phases of the attack, “Megatron” can finally achieve his goals, 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.
We really hope you enjoyed this room. In order to strengthen your knowledge, let’s do a practice analysis.
Here is the real-world scenario for you to tackle:
The infamous Target cyber-attack, which led to one of the largest data breaches in history took place on November 27, 2013.
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
- 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).
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.
The traditional Cyber Kill Chain or Lockheed Martin Cyber Kill Chain was last modified in 2011, which, if you remember, is the date of its establishment. The absence of updates and modifications creates security gaps.
The traditional Cyber Kill Chain was designed to secure the network perimeter and protect against malware threats. 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.
Since the main focus of the framework is on malware delivery and network security, the traditional Cyber Kill Chain will not be able to identify Insider Threats. According to CISA, “The Insider Threat is the potential for an insider to use their authorized access or understanding of an organization to harm that organization.”
We 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.