Madyson  Reilly

Madyson Reilly

1596755400

What is a Second-Order SQL Injection and how can you exploit it successfully?

What is SQL Injection

SQL Injection — the process of injecting SQL language code within data requests that result in application backend database server either surrendering confidential data or cause the execution of malicious scripting content on the database that could result in a complete compromise of the host.

Understanding Second-Order Code Injection

Imagine a scenario wherein a malicious code injected into an application by an attacker which does not get immediately get executed in the application.

Yes, you read that right. It’s a familiar story and it usually goes like this, user-provided data becomes a threat when it is utilized by the application or any other application wherein the injected code provided by the attacker gets activated resulting in successful exploitation.

First -order and Second-order SQL Injection differ primarily in the way that the attacker can simply enter a malicious string and cause the modified code to be executed immediately.

See the difference?

The attacker injects into persistent storage (such as a table row) which is deemed as a trusted source. An attack is subsequently executed by another activity.

Image for post

Credit: portswigger.net

Testing Challenge

The attacking nature of common code injection allows an attacker to discover the vulnerability by observing the application response.

Testing for Second Order SQL Injection is slightly difficult because it requires the attacker to have the knowledge of backend operation of the application.

How can you beat that?

Automated web-application assessment tools are not adequate to identify these vulnerabilities. An automated tool is not smart enough to identify the change in application behavior in any of the subsequent responses caused by the malicious injection in one of the previous queries.

What makes an application vulnerable to Second-order SQL Injection

This kind of vulnerability happens because a good programmer maybe will patch his code to prevent SQL injections in forms where the user can input something BUT he will not do the same thing where a user doesn’t have any sort of interaction with the application database.

Exploit Scenario

A second-order SQL Injection, on the other hand, is a vulnerability exploitable in two different steps:

  1. Firstly, we STORE a particular user-supplied input value in the DB and
  2. Secondly, we use the stored value to exploit a vulnerability in a vulnerable function in the source code which constructs the dynamic query of the web application.

So let’s get down to business and look at how a vulnerable application could be exploited in more detail with the help of a hypothetical scenario:

Example 1

CREATE TABLE USERS ( userId serial PRIMARY KEY, firstName TEXT )

Suppose you have some SAFE code like this, receiving firstName from a form:

$firstname = someEscapeFunction($_POST[“firstName”]);

$SQL = “INSERT INTO USERS (firstname) VALUES (‘{$firstName }’);”;
someConnection->execute($SQL);

So far so good, assuming that someEscapeFunction() does a fine job. It isn’t possible to inject SQL. If I would now send my payload as a value for firstname, you wouldn’t mind:

Payload : bla’); DELETE FROM USERS; //

Now, suppose somebody on the same system wants to transport firstName from USERS to SOME, and does that like this:

$userid = 42; $SQL = “SELECT firstname FROM USERS WHERE (userId={$userid})”; $RS = con->fetchAll($SQL); $firstName = $RS[0][“firstName”];

And then inserts it into SOME table without escaping:

$SQL = “INSERT INTO SOME VALUES (‘{$firstName}’);”;

Malicious query becomes like this:

INSERT INTO SOME VALUES (‘ bla’); DELETE FROM USERS; //

At this point you realise that if the firstname contains some delete command, it will still be executed.

#owasp #hacking #cybersecurity #sql-injection #vulnerability #sql

What is GEEK

Buddha Community

What is a  Second-Order SQL Injection and how can you exploit it successfully?
Cayla  Erdman

Cayla Erdman

1594369800

Introduction to Structured Query Language SQL pdf

SQL stands for Structured Query Language. SQL is a scripting language expected to store, control, and inquiry information put away in social databases. The main manifestation of SQL showed up in 1974, when a gathering in IBM built up the principal model of a social database. The primary business social database was discharged by Relational Software later turning out to be Oracle.

Models for SQL exist. In any case, the SQL that can be utilized on every last one of the major RDBMS today is in various flavors. This is because of two reasons:

1. The SQL order standard is genuinely intricate, and it isn’t handy to actualize the whole standard.

2. Every database seller needs an approach to separate its item from others.

Right now, contrasts are noted where fitting.

#programming books #beginning sql pdf #commands sql #download free sql full book pdf #introduction to sql pdf #introduction to sql ppt #introduction to sql #practical sql pdf #sql commands pdf with examples free download #sql commands #sql free bool download #sql guide #sql language #sql pdf #sql ppt #sql programming language #sql tutorial for beginners #sql tutorial pdf #sql #structured query language pdf #structured query language ppt #structured query language

Madyson  Reilly

Madyson Reilly

1596755400

What is a Second-Order SQL Injection and how can you exploit it successfully?

What is SQL Injection

SQL Injection — the process of injecting SQL language code within data requests that result in application backend database server either surrendering confidential data or cause the execution of malicious scripting content on the database that could result in a complete compromise of the host.

Understanding Second-Order Code Injection

Imagine a scenario wherein a malicious code injected into an application by an attacker which does not get immediately get executed in the application.

Yes, you read that right. It’s a familiar story and it usually goes like this, user-provided data becomes a threat when it is utilized by the application or any other application wherein the injected code provided by the attacker gets activated resulting in successful exploitation.

First -order and Second-order SQL Injection differ primarily in the way that the attacker can simply enter a malicious string and cause the modified code to be executed immediately.

See the difference?

The attacker injects into persistent storage (such as a table row) which is deemed as a trusted source. An attack is subsequently executed by another activity.

Image for post

Credit: portswigger.net

Testing Challenge

The attacking nature of common code injection allows an attacker to discover the vulnerability by observing the application response.

Testing for Second Order SQL Injection is slightly difficult because it requires the attacker to have the knowledge of backend operation of the application.

How can you beat that?

Automated web-application assessment tools are not adequate to identify these vulnerabilities. An automated tool is not smart enough to identify the change in application behavior in any of the subsequent responses caused by the malicious injection in one of the previous queries.

What makes an application vulnerable to Second-order SQL Injection

This kind of vulnerability happens because a good programmer maybe will patch his code to prevent SQL injections in forms where the user can input something BUT he will not do the same thing where a user doesn’t have any sort of interaction with the application database.

Exploit Scenario

A second-order SQL Injection, on the other hand, is a vulnerability exploitable in two different steps:

  1. Firstly, we STORE a particular user-supplied input value in the DB and
  2. Secondly, we use the stored value to exploit a vulnerability in a vulnerable function in the source code which constructs the dynamic query of the web application.

So let’s get down to business and look at how a vulnerable application could be exploited in more detail with the help of a hypothetical scenario:

Example 1

CREATE TABLE USERS ( userId serial PRIMARY KEY, firstName TEXT )

Suppose you have some SAFE code like this, receiving firstName from a form:

$firstname = someEscapeFunction($_POST[“firstName”]);

$SQL = “INSERT INTO USERS (firstname) VALUES (‘{$firstName }’);”;
someConnection->execute($SQL);

So far so good, assuming that someEscapeFunction() does a fine job. It isn’t possible to inject SQL. If I would now send my payload as a value for firstname, you wouldn’t mind:

Payload : bla’); DELETE FROM USERS; //

Now, suppose somebody on the same system wants to transport firstName from USERS to SOME, and does that like this:

$userid = 42; $SQL = “SELECT firstname FROM USERS WHERE (userId={$userid})”; $RS = con->fetchAll($SQL); $firstName = $RS[0][“firstName”];

And then inserts it into SOME table without escaping:

$SQL = “INSERT INTO SOME VALUES (‘{$firstName}’);”;

Malicious query becomes like this:

INSERT INTO SOME VALUES (‘ bla’); DELETE FROM USERS; //

At this point you realise that if the firstname contains some delete command, it will still be executed.

#owasp #hacking #cybersecurity #sql-injection #vulnerability #sql

Introduction to Recursive CTE

This article will introduce the concept of SQL recursive. Recursive CTE is a really cool. We will see that it can often simplify our code, and avoid a cascade of SQL queries!

Why use a recursive CTE ?

The recursive queries are used to query hierarchical data. It avoids a cascade of SQL queries, you can only do one query to retrieve the hierarchical data.

What is recursive CTE ?

First, what is a CTE? A CTE (Common Table Expression) is a temporary named result set that you can reference within a SELECT, INSERT, UPDATE, or DELETE statement. For example, you can use CTE when, in a query, you will use the same subquery more than once.

A recursive CTE is one having a subquery that refers to its own name!

Recursive CTE is defined in the SQL standard.

How to make a recursive CTE?

A recursive CTE has this structure:

  • The WITH clause must begin with “WITH RECURSIVE”
  • The recursive CTE subquery has two parts, separated by “UNION [ALL]” or “UNION DISTINCT”:
  • The first part produces the initial row(s) for the CTE. This SELECT does not refer to the CTE name.
  • The second part recurses by referring to the CTE name in its FROM clause.

Practice / Example

In this example, we use hierarchical data. Each row can have zero or one parent. And it parent can also have a parent etc.

Create table test (id integer, parent_id integer);

insert into test (id, parent_id) values (1, null);

insert into test (id, parent_id) values (11, 1);
insert into test (id, parent_id) values (111, 11);

insert into test (id, parent_id) values (112, 11);

insert into test (id, parent_id) values (12, 1);

insert into test (id, parent_id) values (121, 12);

For example, the row with id 111 has as ancestors: 11 and 1.

Before knowing the recursive CTE, I was doing several queries to get all the ancestors of a row.

For example, to retrieve all the ancestors of the row with id 111.

While (has parent)

	Select id, parent_id from test where id = X

With recursive CTE, we can retrieve all ancestors of a row with only one SQL query :)

WITH RECURSIVE cte_test AS (
	SELECT id, parent_id FROM test WHERE id = 111
	UNION 
	SELECT test.id, test.parent_id FROM test JOIN cte_test ON cte_test.id = test.parent_id

) SELECT * FROM cte_test

Explanations:

  • “WITH RECURSIVE”:

It indicates we will make recursive

  • “SELECT id, parent_id FROM test WHERE id = 111”:

It is the initial query.

  • “UNION … JOIN cte_test” :

It is the recursive expression! We make a jointure with the current CTE!

Replay this example here

#sql #database #sql-server #sql-injection #writing-sql-queries #sql-beginner-tips #better-sql-querying-tips #sql-top-story

Chesley  Wehner

Chesley Wehner

1621542900

Learn SQL: SQL Injection

SQL Injection is a well-known technique used to attack SQL-based applications. In this article, we’ll focus on examples showing how you could exploit database vulnerabilities using this technique, while in the next article we’ll talk about ways how you can protect your application from such attacks.

Data Model

In this article, we’ll use the same data model we’re using throughout this series, so there were no changes in the structure or data of tables, since last time.

the data model

The only thing we’ll do is add some new tables to prove we can do it using SQL injection, as well as delete these tables.

#sql commands #t-sql #sql #sql injection

Cayla  Erdman

Cayla Erdman

1596441660

Welcome Back the T-SQL Debugger with SQL Complete – SQL Debugger

When you develop large chunks of T-SQL code with the help of the SQL Server Management Studio tool, it is essential to test the “Live” behavior of your code by making sure that each small piece of code works fine and being able to allocate any error message that may cause a failure within that code.

The easiest way to perform that would be to use the T-SQL debugger feature, which used to be built-in over the SQL Server Management Studio tool. But since the T-SQL debugger feature was removed completely from SQL Server Management Studio 18 and later editions, we need a replacement for that feature. This is because we cannot keep using the old versions of SSMS just to support the T-SQL Debugger feature without “enjoying” the new features and bug fixes that are released in the new SSMS versions.

If you plan to wait for SSMS to bring back the T-SQL Debugger feature, vote in the Put Debugger back into SSMS 18 to ask Microsoft to reintroduce it.

As for me, I searched for an alternative tool for a T-SQL Debugger SSMS built-in feature and found that Devart company rolled out a new T-SQL Debugger feature to version 6.4 of SQL – Complete tool. SQL Complete is an add-in for Visual Studio and SSMS that offers scripts autocompletion capabilities, which help develop and debug your SQL database project.

The SQL Debugger feature of SQL Complete allows you to check the execution of your scripts, procedures, functions, and triggers step by step by adding breakpoints to the lines where you plan to start, suspend, evaluate, step through, and then to continue the execution of your script.

You can download SQL Complete from the dbForge Download page and install it on your machine using a straight-forward installation wizard. The wizard will ask you to specify the installation path for the SQL Complete tool and the versions of SSMS and Visual Studio that you plan to install the SQL Complete on, as an add-in, from the versions that are installed on your machine, as shown below:

Once SQL Complete is fully installed on your machine, the dbForge SQL Complete installation wizard will notify you of whether the installation was completed successfully or the wizard faced any specific issue that you can troubleshoot and fix easily. If there are no issues, the wizard will provide you with an option to open the SSMS tool and start using the SQL Complete tool, as displayed below:

When you open SSMS, you will see a new “Debug” tools menu, under which you can navigate the SQL Debugger feature options. Besides, you will see a list of icons that will be used to control the debug mode of the T-SQL query at the leftmost side of the SSMS tool. If you cannot see the list, you can go to View -> Toolbars -> Debugger to make these icons visible.

During the debugging session, the SQL Debugger icons will be as follows:

The functionality of these icons within the SQL Debugger can be summarized as:

  • Adding Breakpoints to control the execution pause of the T-SQL script at a specific statement allows you to check the debugging information of the T-SQL statements such as the values for the parameters and the variables.
  • Step Into is “navigate” through the script statements one by one, allowing you to check how each statement behaves.
  • Step Over is “execute” a specific stored procedure if you are sure that it contains no error.
  • Step Out is “return” from the stored procedure, function, or trigger to the main debugging window.
  • Continue executing the script until reaching the next breakpoint.
  • Stop Debugging is “terminate” the debugging session.
  • Restart “stop and start” the current debugging session.

#sql server #sql #sql debugger #sql server #sql server stored procedure #ssms #t-sql queries