ZyXEL Communications ZyWALL 1000 ユーザーズマニュアル

Chapter 29 IDP

ZyWALL USG 1000 User’s Guide

An IDP service group is a set of related packet inspection signatures.

DoS/DDoS

The goal of Denial of Service (DoS) attacks is not to steal information, but to 

disable a device or network on the Internet. 
A distributed denial-of-service (DDoS) attack is one in which multiple 

compromised systems attack a single target, thereby causing denial of service 

for users of the targeted system.

Scan

A scan describes the action of searching a network for an exposed service. An 

attack may then occur once a vulnerability has been found. Scans occur on 

several network levels.
A network scan occurs at layer-3. For example, an attacker looks for network 

devices such as a router or server running in an IP network.
A scan on a protocol is commonly referred to as a layer-4 scan. For example, 

once an attacker has found a live end system, he looks for open ports. 
A scan on a service is commonly referred to a layer-7 scan. For example, once 

an attacker has found an open port, say port 80 on a server, he determines that 

it is a HTTP service run by some web server application. He then uses a web 

vulnerability scanner (for example, Nikto) to look for documented vulnerabilities.

Buffer Overflow

A buffer overflow occurs when a program or process tries to store more data in 

a buffer (temporary data storage area) than it was intended to hold. The excess 

information can overflow into adjacent buffers, corrupting or overwriting the 

valid data held in them. 
Intruders could run codes in the overflow buffer region to obtain control of the 

system, install a backdoor or use the victim to launch attacks on other devices.

Virus/Worm

A computer virus is a small program designed to corrupt and/or alter the 

operation of other legitimate programs. A worm is a program that is designed to 

copy itself from one computer to another on a network. A worm’s uncontrolled 

replication consumes system resources, thus slowing or stopping other tasks.

Backdoor/Trojan

A backdoor (also called a trapdoor) is hidden software or a hardware 

mechanism that can be triggered to gain access to a program, online service or 

an entire computer system. A Trojan horse is a harmful program that is hidden 

inside apparently harmless programs or data.
Although a virus, a worm and a Trojan are different types of attacks, they can be 

blended into one attack. For example, W32/Blaster and W32/Sasser are 

blended attacks that feature a combination of a worm and a Trojan.

Access Control

Access control refers to procedures and controls that limit or detect access. 

Access control attacks try to bypass validation checks in order to access 

network resources such as servers, directories, and files.

Web Attack

Web attacks refer to attacks on web servers such as IIS (Internet Information 

Services).

Table 132   Policy Types (continued)

Table 133   IDP Service Groups

WEB_PHP WEB_MISC WEB_IIS WEB_FRONTPAGE 

WEB_CGI WEB_ATTACKS 

TFTP 

TELNET 

SQL SNMP 

SMTP  RSERVICES 

RPC POP3 POP2  P2P 

ORACLE 

NNTP NETBIOS MYSQL 

MISC_EXPLOIT MISC_DDOS 

MISC_BACKDOOR MISC