Tag Archives: NDR

Threat Hunting II – Recommendations

An effective threat hunting is critical because it is hard to think like attackers and to search for the unknown in an enterprise network. This post may help organizations for an effective and successful threat hunting.

Knowledge of Topology and Environment

The purpose of threat hunting is to find the anomalies and their sources in the network and endpoint. So, a threat hunter should know what is normal and so can understand what is not normal.

From the risk management point of view, critical assets – servers, applications, data – should be known to protect more effectively. With the knowledge of the environment, the threat hunter knows the critical assets and hunts according to this. If there is segmentation in network, it is also critical to know the network topology and networks – or vlans – of these critical assets.

It is also necessary to know which application is running on which operating system, so the threat hunter can know the weaknesses of the system and can search according to these weaknesses.

Effective Endpoint Management

For threat hunting, the most used tools are EDRs. Organizations should be sure that they installed endpoint security tools to all endpoints and detect when they removed or stopped. Asset management is something more than CMDB. It must be managed by security teams whose understanding the criticality of the lack of endpoint security tool in an endpoint.

Intel

Threat intelligence is one of the most important feeds of threat hunting. Threat hunters need to have most recent intelligence and IoCs so they cant perform hunting the latest threats. Many malicious are produced and detected every day. This situation causes a lot of noises about intel. To avoid this noise, hunters should get valuable intelligence about their organization’s sector and geolocation, and integrate these IoCs with SIEM, EDR, etc..

Personnel

We all know that new tactics and techniques are created by attackers in general. The most important reason for this is while security professionals in organizations have to deal with so many different things, attackers can only focus on their target. Even if it so important to have valuable/experienced personnel, if they are dealing with different organizational missions while they are working, it will be difficult for them to think like an hacker and detect the unknown in the network. Threat hunters should focus to their mission to create their methodology and hunt. So, there should be dedicated personnels for threat hunting.

Coordination Across the Organization

Yes, threat hunters work in a strange mission, think like a hacker and search across the network but they must not work alone. A threat hunter should have a good relationships with key personnel in IT departments like network and system admins, help desk personnel and so on. With these relationships, they better understand the network, systems and more importantly the company’s and personnels’ way of doing business. For organization’s perspective, when a threat hunter finds a weaknesses during the hunting process, they inform critical IT personnel for remediation. This team working will result as a success in remediation phase of the incidents or weaknesses.

TTPs

Pyramid of Pain

Intelligence is critical for hunting for the known threats but hunters should be familiar with the TTPs of the attackers against the zero day threats. Threat hunters also should be aware of the updated or newly TTPs. Only with this knowledge hunters can act like an attacker. TTPs are at the top of Pyramid of Pain (defined by David Bianco).

Tools

To disclose the anomaly or malicious activity, threat hunters should use advanced tools like EDR, NDR, SIEM, FIM, etc.. These tools will help hunter to find abnormal activities if configured properly. In different posts, we tried to explain why they should be used.

Virtual Machines Roles in Growing Number of Ransomware Attacks

Symantec Threat Hunter Team published a post about evidence that an increasing number of ransomware attackers are using virtual machines (VMs) in order to run their ransomware payloads on compromised computers. The purpose of using VMs on ransomware attacks is thought to hide the malicious activities. It is stated that this method is used in order to bypass the security solutions in virtual machines and to ensure that malicious codes can be hidden in the virtual machine.

In the past, a similar attack was seen on Windows XP machines by RagnarLocker ransomware. The same method now is used in Windows 7 machines.

It is important to prevent the installation of unauthorized virtual machines in corporate networks and implement NDR solutions to capture the anomalies in the network. In addition, Symantec published these IoCs to detect;

  • 2eae8e1c2e59527b8b4bb454a51b65f0ea1b0b7476e1c80b385f579328752836 – Installer
  • 9f801a8d6b4801b8f120be9e5a157b0d1fc3bbf6ba11a7d202a9060e60b707d8 – runner.exe
  • e5291bae18b0fa3239503ab676cacb12f58a69eb2ec1fd3d0c0702b5a29246cb – VirtualBox
  • d89bd47fb457908e8d65f705f091372251bae3603f5ff59afb2436abfcf976d8 – Mountlocker
  • 8f247e4149742532b8a0258afd31466f968af7b5ac01fdb7960ac8c0643d2499 – Mountlocker

Threat Hunting I – Understanding Threat Hunting

Although Threat Hunting is nothing new, it is a very hot topic lately. Even if you have perimeter and endpoint security devices and SIEM for collecting and correlating logs from them, it is not a good way to wait for incidents coming. Without Threat Hunting, dwell time is increasing more than 150 days, and this is not acceptable anymore. While attackers are working proactively and developing new techniques day by day, security teams need to be more proactive too. Threat Hunting is the most proactive approach in an organization’s security structure and improves its security posture.

Dwell time is the dirty metric nobody wants to talk about in cyber security. It signifies the amount of time threat actors go undetected in an environment, and the industry stats about it are staggering.
Source: Extrahop

In its simplest definition, Threat Hunting is detecting abnormal activities on endpoints and network. But, what to look for hunting threats?

What to Hunt?

Threat Hunting is a continuous process. Hunters should check anything that could be an evidence of an incident.

  • Processes: Processes are important components of OSs. Adversaries may inject malicious code into hijacked processes. Therefore, hunters should check processes and child processes regularly.
  • Binaries: Hunters should check binaries with their checksum, name and other specifications.
  • Network: Network activities to specific destinations and anomalies in network should be checked.
  • Registery: Hunters should check registery key additions and modifications.

The Team

For a continuous hunting, organizations need to have threat hunters in their CSIRT. The difference between analysts and threat hunters is the proactive approach as mentioned before. Also in smaller organizations, SOC analysts may work on threat hunting but actually, a threat hunter may has more specifications than an analyst. In larger organizations, it is important to have a dedicated threat hunting leader and team. This team should has detailed knowledge about;

  • OSs: The Threat Hunting team should have knowledge about OSs that organization is using. This knowledge must include process structures, files, permissions, and registery depending on the OS. This is important because malicious files and attackers make changes in OS here. A threat hunter need to understand what is normal and what is not. Something is not normal could be a sign of an intrusion. For having this knowledge, baselines could be created for all critical systems. These baselines will help to know the normal and the anomalies.
  • Apps: Threat Hunters should have knowledge about the applications used in the organization. It is also important to know perimeter and endpoint security devices and applications used by organization.
  • Business: Threat Hunting team should have knowledge about the organization’s business so they need to follow adversaries working on the organization’s sector and geographical location. It is also important to know third party companies the organization works and communication ways with them.
  • Network: In a big and segmented network structure, it is important to know where the critical assets are.
  • The Lockheed Martin Cyber Kill Chain: Also known as APT phases, represents the phases of an advanced attack.
  • TTPs: IoCs are important components for hunting but they provide to detect “known knowns”. TTPs are at the top of Pyramid of Pain (defined by David Bianco) and especially adversaries’ techniques and tactics should be known those are threatening the organization’s sector and location.
  • Threat Hunting Tools: In CSIRT plan, it needs to be included that which tools and techniques can be used for threat hunting. Threat hunters should have knowledge of these tools and techniques.
  • IR&H Plan: Threat hunting is only a step of proactive approach. If threat hunters successfully find an intrusion or anomaly in systems, they need to know the next step. Who should they inform? What should be done?..etc..

Requirements

  • Threat Intelligence: Threat intelligence is one of the most important feeds of threat hunting. Threat hunters need to have most recent intelligence and IoCs so they cant perform hunting the latest threats.
  • EDR: Threat hunters need IoCs but also need to know how to use these IoCs. After gathering the most recent IoCs from TI platforms, an IoC sweep must be made on endpoints.
  • NDR: Just like endpoints, network traffic also need to be checked with the latest IoCs. For doing this, CSIRT need to collect all east-west and south-north network traffic. NDR devices those have AI capabilities also detect anomalies in the network.
  • SIEM: Depending on the hunt’s scope, the threat hunter may need to check IPS/IDS, proxy, DNS, firewall or some other tools’ logs. Because logs are coming from different sources, CSIRT need to collect and correlate these logs in SIEM and feeding SIEM with the latest IoCs, these logs will more meaningful.
  • FIM: We said that baselines must be created for critical systems. FIM solutions will help CSIRT to create baselines for OSs and alert analysts when an unauthorized transaction is made.

Network Detection and Response

As organizations, and security teams, we purchased many security devices for providing both network and endpoint security. However, attacks continue at the same pace, even we faced bigger attacks last year, and they are getting more sophisticated. So, what is the next step for organizations?

NDR market guide was shared last year by Gartner. As the idea, NDR uses (or must use) artifical intelligence to detect malicious behaviors, both from external threat actors and insider threats.  This means, we will no longer just store the huge network traffic data via full packet capture products, but also detect the anomalies in these captured traffic. So, NDR will play a major role in helping security team to response quicker.

Unfortunately, the only obstacle to the teams last year was not the more sophisticated attacks, but also the “new normal” made security teams so hard. Now, more users are reaching to organization’s sources, getting e-mails and downloading files out of office. Control over users’ behaviors is less and less. When that happens, the need for more sophisticated technologies is also increasing.

MACHINE LEARNING

Even if we implement many security technologies to our structure, attacks are still going on. Now it is necessary to detect whether there is anyone inside as much as protecting the border. Honeypot technologies and EDRs have been used for this for years but these are not enough to decrease the dwell time. If you failed to prevent and detect an attacker inside your network, or an insider threat, it is always difficult to prevent data exfiltration, or your file from being encrypted.

Machine learning is the key here. The main idea is anomaly detection inside the network. The first step is to profile entire organization’s network and users’ and computers’ traffic. After having such a profiling, it will be easier to detect anomalies inside the network. Anomalies can be in different forms like data exfiltration to some rare destinations, uploading files to IP addresses without hostnames, login attempt from strange destinations (for cloud or vpn), and copying in large number of files from an smb share. We expect the NDR to catch all of that, of course more.

CLOUD

More otganizations are using cloud infrastructure more and more. Public, private, or hybrid, cloud infrasturctures are also a part of us. Critical files are stored and applications work there, and the responsibles are the customers for the data’s security.

Think of a scenerio like that; you have users storing files in cloud and they are working with a few of these files during their work. A user, has a permission to reach these files, downloading most of the files in a very short time, then resigns from work. Or, this user’s credentials have been compromised, and someone connected to your cloud from a country that non of your users normally connect and made anomalous behaviors. NDR must cover also cloud and detect these incidents. It is hard to implement a UEBA solution, thus, NDR can be implemented to detect insider threat.

THE NEW NORMAL

Most of the organizations were caught unprepared for Covid situation. Users had to work at home and connected to organizations’ network or cloud from home. That means, users can connect to internet less controlled. An NDR with endpoint capabilities will also cover users at home, corralate users behaviors with your network traffic and can detect threats.