ZyXEL ZyWALL 5 User Guide - Page 281

Chapter 14 Intrusion Detection and Prevention (IDP) Screens 14.3 The Signatures Screen The rules that define how to identify and respond to intrusions are called "signatures". Click SECURITY > IDP > Signatures to see the ZyWALL's signatures. 14.3.1 Attack Types Click SECURITY > IDP > Signature. The Attack Type list box displays all intrusion types supported by the ZyWALL. Other covers all intrusion types not covered by other types listed. To see signatures listed by intrusion type supported by the ZyWALL, select that type from the Attack Type list box. Table 78 SECURITY > IDP > Signature: Attack Types TYPE DESCRIPTION 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. 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. Access Control Access control refers to procedures and controls that limit or detect access. Access control is used typically to control user access to network resources such as servers, directories, and files. Scan Scan refers to all port, IP or vulnerability scans. Hackers scan ports to find targets. They may use a TCP connect() call, SYN scanning (half-open scanning), Nmap etc. After a target has been found, a vulnerability scanner can be used to exploit exposures. Trojan Horse A Trojan horse is a harmful program that's hidden inside apparently harmless programs or data. It could be used to steal information or remotely control a device. P2P Peer-to-peer (P2P) is where computing devices link directly to each other and can directly initiate communication with each other; they do not need an intermediary. A device can be both the client and the server. In the ZyWALL, P2P refers to peer- to-peer applications such as eMule, eDonkey, BitTorrent, iMesh etc. IM IM (Instant Messaging) refers to chat applications. Chat is real-time communication between two or more users via networks-connected computers. After you enter a chat (or chat room), any member can type a message that will appear on the monitors of all the other participants. 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. The IDP VirusWorm category refers to network-based viruses and worms. The Anti-Virus (AV) screen refers to file-based viruses and worms. Refer to the antivirus chapter for additional information on file-based anti-virus scanning in the ZyWALL. Porn The ZyWALL can block web sites if their URLs contain certain pornographic words. It cannot block web pages containing those words if the associated URL does not. ZyWALL 5/35/70 Series User's Guide 281