![]() In short, they occur when an application developer fails to do proper bounds checking with the memory addresses an application utilizes. Cause traffic destined for key servers on the Internet to be directed to the attacker's machine by using NAT.īuffer overflows are the most common form of application vulnerability. Now run through the exercise yourself and list the potential methods an attacker could use to gain access to your internal LAN. protected and why, based on the list of protections installed between the attacker and the host Attacker Filtering Router Firewall Personal Firewall Host 1 Attacker Firewall Host IDS Host 2 9 In the section on the axiom Everything is a target, you saw the various ways in which a web server could be compromised. It is not overly difficult for an attacker to learn the ports actually usedit's certainly much less effort than that required to maintain such an obscure environment. If an attacker were to gain control of an Ethernet switch operating at Layer 2, all the upper layers could be compromised.Ī4 Although Yes, sir is sometimes a necessary response, a better one is to suggest that security through obscurity is not overly valuable, especially when the effects will have an impact on every employee in the company on a day-to-day basis. Cisco Catalyst switches operate at Layer 2 of the OSI model (the Data Link Layer), as illustrated in Figure 6-1. Other switch-related security topics include port security, Switch Port Analyzer (SPAN), Remote SPAN (RSPAN), VLAN access control lists (VACL), private VLANs, rate limiting, and MAC address notification. These strategies include best practices for securing a Layer 2 network, protecting against VLAN hopping attacks, preventing an attacker from manipulating Spanning Tree Protocol (STP) settings, stopping DHCP server and ARP spoofing, preventing Content Addressable Memory ( CAM) table overflow attacks, and disallowing MAC address spoofing. Then, approaches for mitigating a variety of Layer 2 attacks are addressed. This section begins by exploring the nature of Layer 2 switch operation and why it is such an attractive target for attackers. An attacker might be able to use the device ID to physically locate the switch, its IP address to target Telnet or SNMP attacks, or the native VLAN and switch port ID to attempt a VLAN hopping attack. For example, the following information is sent in a CDP advertisement in the clear. Although CDP is a very handy tool for discovering neighboring Cisco devices, you shouldn't allow CDP to advertise unnecessary information about your switch to listening attackers. Secure the use of CDP By default, CDP advertisements are sent on every switch port at 60-second intervals. ![]() Think ahead and try to prevent as many things as possible that might be leveraged to assist an attacker. In other words, don't become complacent and assume that everyone connected to your network will be good citizens and play by the rules. You should be aware of some common weaknesses that can be exploited. You can configure and use many different features on Cisco Catalyst switches. For more information on war driving, check out http. The attacker's goal is to identify poorly secured wireless LAN access points (APs) through which the attacker can connect directly to the victim network. War driving is very similar to war dialing except the attacker drives a car with a high-gain wireless antenna around the physical location of the victim. By dialing these numbers, an attacker can very likely bypass a large part of the victim's security measures because, after a successful war-dialing attack, the attacker might appear to be a trusted employee. From this list of reachable modems, the attacker can then guess which systems are on the other side. In war dialing, the attacker dials the phone number prefixes assigned to the victim or the victim's area, searching for modem connections. War dialing and war driving allow attackers to get into the victim network without going through the front door.
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