Different Ways to Hack Oracle

Oracle is said to be very safe,but still there are ways to hack the Oracle.Some of the techniques used to hack the Oracle are discussed here.

1. SQL Injection
SQL Injection is simply entering information in a web form, and secretly adding some unexpected code, tricking the application to execute that on the database, and return results the programmer had not foreseen. For example, you have a user login form which requests username and password. In the username field, you enter:sean'); select username, password from all_users;--

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2. Default Passwords
Most of the Oracle logins have default passwords.

Username        Password
applsys         apps

ctxsys change_on_install

dbsnmp dbsnmp

outln outln

owa owa

perfstat perfstat

scott tiger

system change_on_install

system manager

sys change_on_install

sys manager

3. Brute Force
Brute force, is the method for banging away at the lock, or keyhole until it breaks,forcibly. In the case of Oracle it means trying every username and password by automating the process with a little bit of code to help you.
For years now, a piece of software called John the Ripper has been available to unix administrators for exactly this task. Now there is a patch available for you so you can use this handy software for banging away at Oracle passwords. Want to speed this process up even more? Prepare in advance a table of all password hashes. Such a table is called a Rainbow table. You will have a different one for each username because the password hashing algorithm uses the username as the salt to the function.

4. Sneaking Data Out The Back Door
In the security world, this concept is known as data exfiltration. It comes from the military term, opposite of infiltration, it means getting out without being noticed. In the context of getting data from a target database, it could be as simple as picking up some tape backups and restoring the database, or getting a copy from a retired crashed disk. However, it can also involve snooping network traffic for relevant packets of data.
Oracle has a package called UTL_TCP, which can make outside connections to other servers. It could be used with a little programming magic, to sending a low bandwidth stream of data from the database to some remote host. Oracle also comes with some useful packages to hide what might be inside your secret stream of data, so make ample use of those if you think an intrusion detection system might be monitoring your activities. They include DBMS_OBFUSCATION_TOOLKIT and DBMS_CRYPTO.