Denial Of Service Attack And Sql Injection Computer Science Essay

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Data supplied by client which is passed to an application without proper data validation by administrator. This attack is command based, which is processed by the database. It performs various actions such as retrieving, alternating data by remove or modifying the information in the data base. Hackers can spot code vulnerabilities to perform SQL injection by using developer's tool against them.

Three forms of SQL injection to access the information from database are as below

Reshaping a query and redirection - a query involved inserting SQL command in to the query being sent to the database. That command allows a direct attack on the database.

Blind Injection -Query forming which results in Boolean value and interpreting HTML output page, resulting in data leakage. Blind holes involve a false scene of security on the host.

Error message based - Select 0/1 where = users name = "satish".This is an error message based code, it echo of failed query that will create a database error and terminate the script. This provides clues as data base type, database structure, query structure.

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Denial-Of-Service Attack:

When the attacker performs the DOS attack the system is no longer available for their intended function. DOS enable unauthorized access to large amount of resources available in the network. The companies that do online business stand still. They need to comprise their incoming order, hacker tries to seize individual component capacity i.e. working memory, processer, disk space and performance of the network. Generally a system is configured with upper limit, so once the hacker is able to overflow the upper limit by DOS attack, system cannot handle any more queries. This results in crash of the network.

Some of the DOS attack

Ping broadcast

Ping of death




Most of the network communication occurs in an unsecured or clear text format, which is easy for an attacker to access the data in the network path or traffic. An attacker is eavesdropping on a network communication is referred as snooping or sniffing. Eavesdropper's ability to monitor or listen to a network communication is the most and biggest security problem for a enterprise level network administrator. The best way to minimise this attack is by encrypting the data on the communication channel i.e. like cryptography. Failing to do this will lead to data being vulnerable.

Spoofing Attack:

Attacker creates a misleading context in order to trick the victim in to making the victim to select inappropriate security -relevant decision. The attacker creates a false but convincing environment around the victim. the victim does something that is good if the false world is real. Unfortunately because of the wrong desertion by the victim, He or she need to compromise a lot in his personal or official data.

For example:

Victim access the online banking page fill all his security details that need to access his online banking, believing that the online bank web page is true but it is not true the victim have taken a security-relevant decision, that make the victim to compromise a lot in his banking details.

Man-in-the -Middle Attack:

Between the client and server an attacker can penetrate and perform his attack

Once the attacker is in the middle the attacker can perform


Key manipulation

Downgrade attack


Injection: attacker can possible add packet to an already existing connection it is only possible in full duplex connection. The attacker can change the sequence numbers and have the connection synchronized while injecting packets. If Man in middle attack is a proxy attack it is even easier to inject there are two distinct connections

Key manipulation:

Modifying the public key exchange by server and client, when two or more client share the same secret each of them can impersonate the server with another client

Filtering- the payload can be changed only in full duplex

In this cases where one time authentication is used in this cases the password is useless but hijacking an already authenticated session is critical

ARP poisoning is one of the man in the middle attack

Password-Based Attack:

In most of the operating systems and network systems a common denominator is password-based access control. So it all means that the access to the computer or the network you want to access are determined by "who u r?", that is, the users username and password. For network validation in older applications always does not allow protected identity information as it passes through.

So if an attacker has the valid user account details, he has the same rights as the original user. So if the user has the administrator level rights, the attacker also has the same level of rights, were he can create a new account for use in later times.

With the valid information, the attacker can do the following

Modify, delay the data or rerouting.

Modify server and network configuration, including routing table and access control.

Obtain network information, valid user name and computer names.

Cross site Scripting: