Types of Attacks

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Old 15-Dec-2009
Arrow Types of Attacks

Types of Attacks
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Types of Attacks
* Eavesdropping
* Snooping
* Interception
* Modification Attacks
* Repudiation Attacks
* Denial-of-service (DoS) Attacks
* Distributed denial-of-service (DDoS) Attacks
* Back door Attacks
* Spoofing Attacks
* Man-in-the-Middle Attacks
* Replay Attacks
* Password Guessing Attacks

Eavesdropping - This is the process of listening in or overhearing parts of a conversation. It also includes attackers listening in on your network traffic. Its generally a passive attack, for example, a coworker may overhear your dinner plans because your speaker phone is set too loud. The opportunity to overhear a conversation is coupled with the carelessness of the parties in the conversation.

Snooping - This is when someone looks through your files in the hopes of finding something interesting whether it is electronic or on paper. In the case of physical snooping people might inspect your dumpster, recycling bins, or even your file cabinets; they can look under your keyboard for post-It-notes, or look for scraps of paper tracked to your bulletin board. Computer snooping on the other hand, involves someone searching through your electronic files trying to find something interesting.

Interception - This can be either an active or passive process. In a networked environment, a passive interception might involve someone who routinely monitors network traffic. Active interception might include putting a computer system between sender and receiver to capture information as it is sent. From the perspective of interception, this process is covert. The last thing a person on an intercept mission wants is to be discovered. Intercept missions can occur for years without the knowledge of the intercept parties.

Modification Attacks - This involves the deletion, insertion, or alteration of information in an unauthorized manner that is intended to appear genuine to the user. These attacks can be very hard to detect. The motivation of this type of attack may be to plant information, change grades in a class, alter credit card records, or something similar. Website defacements are a common form of modification attacks.

Repudiation Attacks - This makes data or information to appear to be invalid or misleading (Which can even be worse). For example, someone might access your email server and inflammatory information to others under the guise of one of your top managers. This information might prove embarrassing to your company and possibly do irreparable harm. This type of attack is fairly easy to accomplish because most email systems don't check outbound email for validity. Repudiation attacks like modification attacks usually begin as access attacks.

Denial-of-service Attacks - They prevent access to resources by users by users authorized to use those resources. An attacker may try to bring down an e-commerce website to prevent or deny usage by legitimate customers. DoS attacks are common on the internet, where they have hit large companies such as Amazon, Microsoft, and AT&T. These these attacks are often widely publicized in the media. Several types of attacks can occur in this category. These attacks can deny access to information, applications, systems, or communications. A DoS attack on a system crashes the operation system (a simple reboot may restore the server to normal operation). A common DoS attack is to open as many TCP sessions as possible; This type of attack is called TCP SYN flood DoS attack. Two of the most common are the ping of death and the buffer overflow attack. The ping of death operates by sending Internet control message protocol (ICMP) packets that are lrger than the system can handle. Buffer overflow attacks attempt to put more data into the buffer than it can handle. Code red, slapper and slammer are attacks that took advantage of buffer overflows, sPing is an example of ping of death.

Distributed Denial-of-service Attacks - This is similar to a DoS attack. This type of attack amplifies the concepts of DoS attacks by using multiple computer systems to conduct the attack against a single organization. These attacks exploit the inherent weaknesses of dedicated networks such as DSL and Cable. These permanently attached systems have little, if any, protection. The attacker can load an attack program onto dozens or even hundreds of computer systems that use DSL or Cable modems. The attack program lies dormant on these computers until they get attack signal from the master computer. This signal triggers these systems which launch an attack simultaneously on the target network or system.

Back door Attacks - This can have two different meanings, the original term back door referred to troubleshooting and developer hooks into systems. During the development of a complicated operating system or application, programmers add back doors or maintenance hooks. These back doors allow them to examine operations inside the code while the program is running. The second type of back door refers to gaining access to a network and inserting a program or utility that creates an entrance for an attacker. The program may allow a certain user to log in without a password or gain administrative privileges. A number of tools exist to create a back door attack such as, Back Orifice (Which has been updated to work with windows server 2003 as well as erlier versions), Subseven,NetBus, and NetDevil. There are many more. Fortunately, most anti-virus software will recognize these attacks.

Spoofing Attacks - This is an attempt by someone or something to masquerade as someone else. This type of attack is usually considered as an access attack. The most popular spoofing attacks today are IP spoofing and DNS spoofing. The goal of IP spoofing is to make the data look like it came from a trusted host when it really didn't. With DNS spoofing, The DNS server is given information about a name server that it thinks is legitimate when it isn't. This can send users to a website other than the one they wanted to go to.

Man-in-the-Middle Attacks - This can be fairly sophisticated, This type of attack is also an access attack, but it can be used as the starting point of a modification attack. This involves placing a piece of software between a server and the user that neither the server administrators nor the user are aware of. This software intercepts data and then send the information to the server as if nothing is wrong. The server responds back to the software, thinking it's communicating with the legitimate client. The attacking software continues sending information to the server and so forth.

Replay Attacks - These are becoming quite common, This occur when information is captured over a network. Replay attacks are used for access or modification attacks. In a distributed environment, logon and password information is sent over the network between the client and the authentication system. The attacker can capture this information and replay it later. This can also occur security certificates from systems such as kerberos: The attacker resubmits the certificate, hoping to be validated by the authentication system, and circumvent any time sensitivity.

Password Guessing Attacks - This occur when an account is attacked repeatedly. This is accomplished by sending possible passwords to an account in a systematic manner. These attacks are initially carried out to gain passwords for an access or modification attack. There are two types of password guessing attacks:

Brute-force attack: Attempt to guess a password until a successful guess occurs. This occurs over a long period. To make passwords more difficult to guess, they should be longer than two or three characters (Six should be the bare minimum), be complex and have password lockout policies.
- Dictionary attack: This uses a dictionary of common words to attempt to find the users password. Dictionary attacks can be automated, and several tools exist in the public domain to execute them.

Well, there you have it, the only way basically to prevent these types of attacks is to get a good firewall, anti-virus software, and a good Intrusion Detection System (IDS). Tell your firewall to drop ICMP packets, that will prevent ICMP flooding.
TCP/IP and UDP attacks
TCP attacks:

1. TCP SYN or TCP ACK Flood Attack
2. TCP Sequence Number Attack
3. TCP/IP Hijacking

The following UDP attacks:

1. ICMP Attacks
2. Smurf Attacks
3. ICMP Tunneling

TCP operates using synchronized connections. The synchronization is vulnerable to attack; this is probably the most common attack used today. The synchronization or handshake, process initiates a TCP connection. This handshake is particularly vulnerable to a DoS attack referred to as the TCP SYN Flood attack. The process is also susceptible to access and modification attacks, which are briefly explained in the following sections.

TCP SYN or TCP ACK Flood Attack - This attack is very common... The purpose of this attack is to deny service. The attack begins as a normal TCP connection: the client and the server exchange information in TCP packets. The TCP client continues to send ACK packets to the server, these ACK packets tells the server that a connection is requested. The server thus responds to the client with a ACK packet, the client is supposed to respond with another packet accepting the connection to establish the session. In this attack the client continually send and receives the ACK packets but it does not open the session. The server holds these sessions open, awaiting the final packet in the sequence. This cause the server to fill up the available connections and denies any requesting clients access.

TCP Sequence Number Attack - This is when the attacker takes control of one end of a TCP session. The goal of this attack is to kick the attacked end of the network for the duration of the session. Only then will the attack be successful. Each time a TCP message is sent the client or the server generates a sequence number. The attacker intercepts and then responds with a sequence number similar to the one used in the original session. This attack can then hijack or disrupt a session. If a valid sequence number is guessed the attacker can place himself between the client and the server. The attacker gains the connection and the data from the legitimate system. The only defense of such an attack is to know that its occurring... There is little that can be done...

TCP Hijacking - This is also called active sniffing, it involves the attacker gaining access to a host in the network and logically disconnecting it from the network. The attacker then inserts another machine with the same IP address. This happens quickly and gives the attacker access to the session and to all the information on the original system.

UDP packets aren't connection oriented and don't require the synchronization process as with TCP. UDP packets, however, are susceptible to interception, thus it can be attacked. UDP, like TCP, doesn't check the validity of an IP address. The nature of this layer is to trust the layer above it (I'm referring to the IP layer). The most common UDP attacks involve UDP flooding. UDP flooding overloads services, networks, and servers. Large streams of UDP packets are focused at a target, causing UDP services on that host to shut down. It can also overload the network and cause a DoS situation to occur.

ICMP Attacks - This occur by triggering a response from the ICMP protocol when it responds to a seemingly legitimate request (think of it as echoing). Ping for instance, that uses the ICMP protocol. sPing is a good example of this type of attack, it overloads te server with more bytes than it can handle, larger connections. Its ping flood.

Smurf Attacks - This attack uses IP spoofing and broadcasting to send a ping to a group of hosts on a network. When a host is pinged it send back ICMP message traffic information indicating status to the originator. If a broadcast is sent to network, all hosts will answer back to the ping. The result is an overload of network and the target system. The only way to prevent this attack is to prohibit ICMP traffic on the router.

ICMP Tunneling - ICMP can contain data about timing and routes. A packet can be used to hold information that is different from the intended information. This allows an ICMP packet to be used as a communications channel between two systems. The channel can be used to send a Trojan horse or other malicious packet. The counter measure is to deny ICMP traffic on your network.

Well, i hope you have learned something and now know more about these attacks than what you thought it seems... ICMP can be very dangerous...

Old 16-Dec-2009
Und3rgr0und J4tt1
Re: Types of Attacks

emotional attack

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