I have spent countless hours analyzing and defending against network threats. While many people are familiar with the common Layer 3 and 4 attacks, Layer 2 attacks are often overlooked but can be just as devastating to an organization’s network security. Today, I am excited to dive deeper into this topic and discuss the top five Layer 2 attacks that every cybersecurity professional should be aware of. By understanding these threats, you can better protect your company’s network and keep your sensitive data out of the hands of hackers. So, without further ado, let’s unmask the hidden dangers lurking within these attacks.
What are five layer 2 attacks?
Additionally, other types of layer 2 attacks include double tagging and Cisco Discovery Protocol (CDP) reconnaissance. Being aware of these attacks and implementing proper security measures can help protect your network from potential security breaches.
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1. Implementing VLAN to Prevent VLAN Hopping: VLAN hopping is a common type of layer 2 attack where an attacker can access data on a network segment to which they shouldn’t have access. Using VLAN can prevent this from happening by segregating the network into different subnets.
2. Controlling MAC Address Flooding: A MAC address flooding attack can cause the switch device to become overburdened with requests and cause a Denial of Service (DoS) condition. Switches need to be configured correctly to prevent MAC address flooding attacks.
3. Using Port Security Features: Network administrators can use port security features in switches to restrict the number of MAC addresses that can be connected to a port. This can help prevent unauthorized access and limit the impact of layer 2 attacks.
4. Protecting Spanning Tree Protocol (STP): STP is a protocol used by switches to prevent network loops. However, hackers can use it to launch an STP manipulation attack, causing network-wide disruption. STP should be protected via configuration settings that prevent unauthorized access.
5. Regular Security Assessments: Frequent security assessments help identify vulnerabilities and increase awareness of security threats. Network administrators can work with digital security experts to perform risk assessments and identify gaps in their network security.
it is important to understand the different types of network attacks that can be launched against customers, employees or even the entire company. Layer 2 attacks are a type of network attack that is aimed at exploiting vulnerabilities in network protocols and technologies that exist at the data link layer.
Address Resolution Protocol Attacks
Address Resolution Protocol (ARP) is a protocol used to convert an IP address to a physical (MAC) address. ARP attacks occur when an attacker sends fake ARP messages to a target machine. ARP cache poisoning, also known as ARP spoofing, tricks the victim computer into binding the attacker’s MAC address with the IP address of the victim machine. In this way, the attacker can eavesdrop, intercept, and modify network traffic. Defenses against ARP attacks include using static ARP tables, implementing network access control lists (ACLs), and enabling Address Resolution Protocol Inspection (ARPI).
CAM Table Overflows
Content Addressable Memory (CAM) is a table used by switches to identify the port associated with a specific MAC address. CAM table overflows exploit a vulnerability in this technology that allows for the flooding of the CAM table with fake MAC addresses. Once the CAM table is full, a switch starts broadcasting network traffic out of all ports, including those that should be blocked. This allows an attacker to intercept and modify network traffic and launch a variety of other attacks. Some defenses against CAM table overflows include limiting the number of MAC addresses that can be learned per port, port-level access controls, and implementing rate limiting.
Spanning Tree Protocol Attacks
The Spanning Tree Protocol (STP) is a protocol used by switches to prevent network loops. STP switches exchange Bridge Protocol Data Units (BPDUs) to establish the root bridge of the network. If an attacker can manipulate the traffic, the attacker can intercept and modify data packets. STP attacks are primarily launched through fake BPDUs which purport to be from a switch with a higher root priority. This could effectively change the topology of the network and redirect network traffic towards the attacker. To prevent STP attacks, a network must be well-designed, with limited redundant paths and enabling root guard.
MAC Spoofing
MAC Spoofing is a technique used by attackers to change the source address of network traffic to bypass security controls. It is usually a part of a larger attack and can be done manually, via software, or hardware. The attacker could then launch other attacks such as ARP spoofing, IP spoofing, or DHCP spoofing; with the latter being aimed at rogue DHCP servers assigning counterfeit IP addresses. To prevent MAC Spoofing requires network access control, virtual local area network membership, and protocol analysis.
Switch Spoofing
Switch Spoofing is a type of attack where an attacker uses rogue hardware to trick a computer into thinking it is connected to an expected switch. After gaining access, the attacker can launch a variety of other attacks in the network. One way to prevent switch spoofing is through the use of Dynamic Host Configuration Protocol (DHCP); since, a user’s IP address can reveal the rogue device’s presence in the network. Network Access Control may also limit communication from unknown devices into the network.
Double Tagging
Double tagging, also known as VLAN hopping attacks, exploits Multicast VLAN Registration (MVR) protocols that are supposed to ensure that only authorized VLANs pass through the switch. Attackers can send messages with double VLAN tags to bypass MVR control and penetrate the network. The result is that attackers can gain access to privileged information, steal data, and launch other attacks. Defenses against double tagging may include physical security, VLAN-based ACLs, and checking incoming traffic for double tags.
Cisco Discovery Protocol Reconnaissance
Cisco Discovery Protocol is a proprietary protocol used by Cisco networking equipment to identify nearby Cisco equipment and exchange information between them. Reconnaissance is the practice of trying to determine the topology of a given network, and Cisco Discovery Protocol can be used as a tool by attackers to glean information about a network. Attackers may capture this information and use it for malicious purposes. As a countermeasure, access control lists can be used and only specific devices should be allowed in the network infrastructure.
In conclusion, understanding and preparing for different forms of Layer 2 network attacks are necessary to protect the company’s resources, customers, networks, and confidential data. It is important to have an overarching control strategy that emphasizes multiple layers of defense, including policies, procedures, people, and technology in the face of prospective threats.
