ZyXEL UAG715 User Guide - Page 330

LAND Attack, UDP Flood Attack, Protocol Anomaly Background Information

Page 330 highlights

Chapter 27 ADP Figure 225 SYN Flood LAND Attack In a LAND attack, hackers flood SYN packets into a network with a spoofed source IP address of the network itself. This makes it appear as if the computers in the network sent the packets to themselves, so the network is unavailable while they try to respond to themselves. UDP Flood Attack UDP is a connection-less protocol and it does not require any connection setup procedure to transfer data. A UDP flood attack is possible when an attacker sends a UDP packet to a random port on the victim system. When the victim system receives a UDP packet, it will determine what application is waiting on the destination port. When it realizes that there is no application that is waiting on the port, it will generate an ICMP packet of destination unreachable to the forged source address. If enough UDP packets are delivered to ports on victim, the system will go down. Protocol Anomaly Background Information The following sections may help you configure the protocol anomaly profile screen (see Section 27.3.5 on page 324) HTTP Inspection and TCP/UDP/ICMP Decoders The following table gives some information on the HTTP inspection, TCP decoder, UDP decoder and ICMP decoder UAG protocol anomaly rules. Table 125 HTTP Inspection and TCP/UDP/ICMP Decoders LABEL DESCRIPTION HTTP Inspection APACHE-WHITESPACE ATTACK This rule deals with non-RFC standard of tab for a space delimiter. Apache uses this, so if you have an Apache server, you need to enable this option. ASCII-ENCODING ATTACK This rule can detect attacks where malicious attackers use ASCIIencoding to encode attack strings. Attackers may use this method to bypass system parameter checks in order to get information or privileges from a web server. 330 UAG715 User's Guide

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Chapter 27 ADP
UAG715 User’s Guide
330
Figure 225
SYN Flood
LAND Attack
In a LAND attack, hackers flood SYN packets into a network with a spoofed source IP address of the
network itself. This makes it appear as if the computers in the network sent the packets to
themselves, so the network is unavailable while they try to respond to themselves.
UDP Flood Attack
UDP is a connection-less protocol and it does not require any connection setup procedure to
transfer data. A UDP flood attack is possible when an attacker sends a UDP packet to a random port
on the victim system. When the victim system receives a UDP packet, it will determine what
application is waiting on the destination port. When it realizes that there is no application that is
waiting on the port, it will generate an ICMP packet of destination unreachable to the forged source
address. If enough UDP packets are delivered to ports on victim, the system will go down.
Protocol Anomaly Background Information
The following sections may help you configure the protocol anomaly profile screen (see
Section
27.3.5 on page 324
)
HTTP Inspection and TCP/UDP/ICMP Decoders
The following table gives some information on the HTTP inspection, TCP decoder, UDP decoder and
ICMP decoder UAG protocol anomaly rules.
Table 125
HTTP Inspection and TCP/UDP/ICMP Decoders
LABEL
DESCRIPTION
HTTP Inspection
APACHE-WHITESPACE ATTACK
This rule deals with non-RFC standard of tab for a space delimiter.
Apache uses this, so if you have an Apache server, you need to enable
this option.
ASCII-ENCODING ATTACK
This rule can detect attacks where malicious attackers use ASCII-
encoding to encode attack strings. Attackers may use this method to
bypass system parameter checks in order to get information or privileges
from a web server.