Distributed DOS Attacks

DOS attacks are not new, in fact they have been aroun for a long time. However, there has been a recent wave of Distributed Denial of services attacks, which pose a great threat to security and are on the verge of overtaking Viruses/Trojans to become  the deadliest threat to Internet security. In a distributed DOS Attack, a group of say, five hackers join and decide to bring a Fortune 500 company's server down. Now, each one of them breaks into a smaller less-protected network and takes control. So, now they have five networks and supposing...

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Hack Windows Login Password

To hack the Windows login password, reboot and wait for the message: :"Starting Windows 9x..." When you see this on the screen, press F8. The boot menu will come up. Select option 7, to boot into Dos. Then go to the Windows directory by typing C:/cd windows Then, rename all files with the extension .pwl by typing the following command: C:/windows>ren*.pwl*.xyz or, delete them by typing C:/windows>del*.pwl*.xyz Now, when the Windows password login pops up, you can write anything in the place where the password has got to be typed. As...

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BIOS Passwords

BIOS passwords are the basic settings on your computer, such as how many and what kinds of disk drives ou have, which ones are enabled and which are disabled and which ones are used for booting. These settings are held in a CMOS chip on the mother board. A tiny battery keeps this chip always running so that whenever  you turn your computer off, it still remembers its instructions. A common method of entering the BIOS is pressing the Del key at boot up. Other common methods are pressing the keys Ctrl + Alt + Esc or only Ctrol + Esc. Most ...

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what is password?

Passwords are one of the oldest forms of authentication mechanism being used on systems accross the world. Password prompts, where one is asked to enter the correct username-password pair, are what prevent infiltration and ensure privacy. Every computer criminal aspires to be able to go past the password prompt and gain illegal access to sensitive data for malicious purposes. Even the data on Windows systems is protected through the password protection mechanism.       As soon as one boots a Windows system, one is greeted...

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UDP-flood attack

A UDP-flood attack typically exploits the target system's chargen or echo services to create an infinite loop between two or more UDP services. CERT describes UDP-flood attacks as follows: When a connection is established between two UDP services, each of which produces output, these two services can produce a very high number of packets that can lead to a denial of service on the machine(s)where the services are offered. Anyone with network connectivity can launch an attack; no account access is needed. For example, by connecting a host's chargen...

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Smurf Attacks

A smurf attack is a sort of brute-force DOS attack in which a huge number of ping requests containing spoofed source IP addresses from within the target network is sent to a system (normally the router) within that network. When the router gets a ping, or echo request message, it sends an echo reply message to the spoofed IP address, flooding the network with packets, thereby clogging the network and preventing legitimate users from obtaining network services....

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Detecting a SYN-Flood Attack

After the target system has tried to send a SYN/ACK packet to the client, and while it is waiting to receive an ACK packet, the existing connection is said to be half open, or the host is said to be in the SYN_RECEIVED state. If your system is in this state, it may well be experiencing a SYN-flood attack. To determine whether connections on your system are half open, type the netstat command; the parameters passed and the results displayed will vary from system to system. Here's an example: C:\windows>netstat -a Active Connections Proto Local...

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Land Attacks

A land attack is similar to a SYN attack, the only difference  being that instead of including an invalid IP address, the SYN packets include the IP address of the target system itself. More specifically, the source IP address and port number are identical to the destination IP address and port number. As a result, an infinite loop is created within the target system, which ultimately hangs and crashes. Countermeasure :- The easiest way to protect your system against land attacks is to install a firewall or filtering utility that filters...

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SYN/ACK Packets

To gain a better understanding of SYN and ACK packets, read the following: ACK. TCP/IP demands that both the source and destination systems transmit and receive acknowledgement messages to confirm the safe and proper transfer of data. These acknowledgement messages are known as ACK messages or ACK packets. For example, suppose there are two systems, A and B, and that A sends the first (X1) of a series of packets to B. A will not send the second packet in the series (X2) to B until B acknowledges that it received the first packet (ACK X1). If A...

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SYN-Flood Attacks

This post focuses on one of the most common and easiest to execute DOS attacks, known as SYN flooding. The idea behind SYN flooding is to flood the target system with connection requests from spoofed source addresses. As the target system tries to establish full connections with all these requests, its memory is hogged. As a result, the target system is unable to provide services to legitimate users or clients. The further clarify, suppose you have a single telephone connection with 10 parallel lines --- that is, 10 lines with the same telephone...

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Teardrop Attacks

Whenever data is sent over the Internet, it is broken into fragments at the source system and reassembled at the destination system. For example, suppose you need to send 4,000 bytes of data from one system to another. Rather than sending the entire chunk in a single packet, the data is broken down into smaller packets, each packet carrying a specified range of data like so: Packet 1 will carry bytes       1-1500. Packet 2 will carry bytes 1501-3000. Packet 3 will carry bytes 3001-4000. Each packet has an Offiset...

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Ping of Death

The ping command makes use of the ICMP echo request and echo reply messages and is commonly used to determine whether the remote host is alive. In a Ping of Death attack, however, ping causes the remote system to hang, reboot, or crash. To do so, the attacker uses the ping command in conjunction with the -l argument (used to specify the size of the packet sent) to ping the target system with a data packet that exceeds the maximum bytes allowed by TCP/IP (65,536). For example, the following ping command creates a giant datagram  that is 65,540...

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DOS attacks

A denial of service (DOS) attack is an attack that clogs up so much memory on the target system that it cannot serve its users, or it causes the target system to crash, reboot, or otherwise deny services to legitimate users. These days, DOS attacks are very common; indeed, just about every server is bound to experience such an attack at some time or another. There are several different kinds of DOS attacks, the most popular of which are follows: Ping of Death Teardrop attacks SYN-flood attacks  Land attacks Smurf  attacks UPD-flood attacks Distributed...

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What is hacking?

A hacker is often someone who creates and modifies computer software and computer hardware, including computer programming, administration, and security-related items. In computer security, a hacker is usually someone who works with the security mechanisms for computer and network systems to strengthen them, it more often in used incorrectly, especially in the mass media, to refer to those who seek access despite them.  ...

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