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Windows Server Threat Detection

Detecting Windows Server Security Threats with Advanced Event Log Analyzers

Windows Server Threat DetectionWindows Servers stand as prime targets for hackers and malicious actors due to their widespread usage and historical vulnerabilities. These systems often serve as the backbone for critical business operations, housing sensitive data and facilitating essential services. However, their prevalence also makes them vulnerable to cyber threats, including ransomware attacks, distributed denial-of-service (DDoS) assaults and more.

Windows Servers have a documented history of vulnerabilities and exploits, which further intensifies their attractiveness to attackers seeking to exploit weaknesses for unauthorized access or data theft. Consequently, it is paramount for organizations to prioritize mitigating these risks and safeguarding the integrity and continuity of operations within Windows Server environments.

Fortunately, tools like EventLog Analyzer offer robust capabilities for automatically identifying and countering such threats, uplifting the security posture of Windows Server setups. To effectively leverage these defenses, it's imperative to understand the nature of common Windows server threats and how they manifest. In this document, we delve into several prevalent threats targeting Windows servers and outline strategies for their detection and mitigation.

Furthermore, implementing robust security measures, such as regular patching, network segmentation, intrusion detection systems, and data encryption, Windows VM Backups, is essential to fortify Windows Servers against potential threats and ensure the resilience of critical business functions.

Key Topics:

Common Windows Server Threats

Windows Server, Ransomware, Threats, Phishing, DoS, Attacks, EventLog, Log, Detection

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Event Log Monitoring System

Event Log Monitoring System: Implementation, Challenges & Standards Compliance. Enhance Your Cybersecurity Posture

eventlog analyzerAn event log monitoring system, often referred to as an event log management, is a critical component to IT security & Management, that helps organizations strengthen their cybersecurity posture. It’s a sophisticated software solution designed to capture, analyze, and interpret a vast array of event logs generated by various components within an organization's IT infrastructure such as firewalls (Cisco ASA, Palo Alto etc), routers, switches, wireless controllers, Windows servers, Exchange server and more.

These event logs can include data on user activities, system events, network traffic, and security incidents and more. By centralizing and scrutinizing these logs in real-time, event log monitoring systems play a pivotal role in enhancing an organization's security posture, enabling proactive threat detection, and facilitating compliance with regulatory requirements.

Key Topics:

Event Log Categories

Event Log Monitoring Systems empowers organizations to identify and respond to potential security threats, operational issues, and compliance breaches promptly, making it an indispensable tool for maintaining the integrity and reliability of modern digital ecosystems.

All logs contain the following basic information:

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How to Perform TCP SYN Flood DoS Attack & Detect it with Wireshark - Kali Linux hping3

wireshark logoThis article will help you understand TCP SYN Flood Attacks, show how to perform a SYN Flood Attack (DoS attack) using Kali Linux & hping3 and correctly identify one using the Wireshark protocol analyser. We’ve included all necessary screenshots and easy to follow instructions that will ensure an enjoyable learning experience for both beginners and advanced IT professionals.

DoS attacks are simple to carry out, can cause serious downtime, and aren’t always obvious. In a SYN flood attack, a malicious party exploits the TCP protocol 3-way handshake to quickly cause service and network disruptions, ultimately leading to an Denial of Service (DoS) Attack. These type of attacks can easily take admins by surprise and can become challenging to identify. Luckily tools like Wireshark makes it an easy process to capture and verify any suspicions of a DoS Attack.

Key Topics:

There’s plenty of interesting information to cover so let’s get right into it.

How TCP SYN Flood Attacks Work

When a client attempts to connect to a server using the TCP protocol e.g (HTTP or HTTPS), it is first required to perform a three-way handshake before any data is exchanged between the two. Since the three-way TCP handshake is always initiated by the client it sends a SYN packet to the server.

 tcp 3 way handshake

The server next replies acknowledging the request and at the same time sends its own SYN request – this is the SYN-ACK packet. The finally the client sends an ACK packet which confirms both two hosts agree to create a connection. The connection is therefore established and data can be transferred between them.

Read our TCP Overview article for more information on the 3-way handshake

In a SYN flood, the attacker sends a high volume of SYN packets to the server using spoofed IP addresses causing the server to send a reply (SYN-ACK) and leave its ports half-open, awaiting for a reply from a host that doesn’t exist:

Performing a TCP SYN flood attack

In a simpler, direct attack (without IP spoofing), the attacker will simply use firewall rules to discard SYN-ACK packets before they reach him. By flooding a target with SYN packets and not responding (ACK), an attacker can easily overwhelm the target’s resources. In this state, the target struggles to handle traffic which in turn will increase CPU usage and memory consumption ultimately leading to the exhaustion of its resources (CPU and RAM). At this point the server will no longer be able to serve legitimate client requests and ultimately lead to a Denial-of-Service.

How to Perform a TCP SYN Flood Attack with Kali Linux & hping3

However, to test if you can detect this type of a DoS attack, you must be able to perform one. The simplest way is via a Kali Linux and more specifically the hping3, a popular TCP penetration testing tool included in Kali Linux.

Alternatively Linux users can install hping3 in their existing Linux distribution using the command:

# sudo apt-get install hping3

In most cases, attackers will use hping or another tool to spoof IP random addresses, so that’s what we’re going to focus on.  The line below lets us start and direct the SYN flood attack to our target (192.168.1.159): 

# hping3 -c 15000 -d 120 -S -w 64 -p 80 --flood --rand-source 192.168.1.159

Let’s explain in detail the above command:

We’re sending 15000 packets (-c 15000) at a size of 120 bytes (-d 120) each. We’re specifying that the SYN Flag (-S) should be enabled, with a TCP window size of 64 (-w 64). To direct the attack to our victum’s HTTP web server we specify port 80 (-p 80) and use the --flood flag to send packets as fast as possible. As you’d expect, the --rand-source flag generates spoofed IP addresses to disguise the real source and avoid detection but at the same time stop the victim’s SYN-ACK reply packets from reaching the attacker.

How to Detect a SYN Flood Attack with Wireshark

Now the attack is in progress, we can attempt to detect it. Wireshark is a little more involved than other commercial-grade software. However, it has the advantage of being completely free, open-source, and available on many platforms.

In our lab environment, we used a Kali Linux laptop to target a Windows 10 desktop via a network switch. Though the structure is insecure compared to many enterprise networks, an attacker could likely perform similar attacks after some sniffing. Recalling the hping3 command, we also used random IP addresses, as that’s the method attackers with some degree of knowledge will use.

Even so, SYN flood attacks are quite easy to detect once you know what you’re looking for. As you’d expect, a big giveaway is the large amount of SYN packets being sent to our Windows 10 PC.

Straight away, though, admins should be able to note the start of the attack by a huge flood of TCP traffic. We can filter for SYN packets without an acknowledgment using the following filter:  tcp.flags.syn == 1 and tcp.flags.ack == 0

tcp syn flood attack detection with wireshark

As you can see, there’s a high volume of SYN packets with very little variance in time. Each SYN packet shows it’s from a different source IP address with a destination port 80 (HTTP), identical length of 120 and window size (64). When we filter with tcp.flags.syn == 1 and tcp.flags.ack == 1 we can see that the number of SYN/ACKs is comparatively very small. A sure sign of a TCP SYN attack.

tcp syn flood attack detection with wireshark

We can also view Wireshark’s graphs for a visual representation of the uptick in traffic. The I/O graph can be found via the Statistics>I/O Graph menu. It shows a massive spike in overall packets from near 0 to up to 2400 packets a second.

tcp syn flood attack wireshark graph

By removing our filter and opening the protocol hierarchy statistics, we can also see that there has been an unusually high volume of TCP packets:

tcp syn flood attack wireshark protocol hierarchy stats

All of these metrics point to a SYN flood attack with little room for interpretation. By use of Wireshark, we can be certain there’s a malicious party and take steps to remedy the situation.

Summary

In this article we showed how to perform a TCP SYN Flood DoS attack with Kali Linux (hping3) and use the Wireshark network protocol analyser filters to detect it. We also explained the theory behind TCP SYN flood attacks and how they can cause Denial-of-Service attacks.

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