What is SQL Injection? | Types of SQL injections | SQL Example & Prevention
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What is SQL Injection?

01/13/2021 by admin with 0 comments

What is SQL Injection? How to Prevent SQL Injection

SQL injection is a type of attack where the backend database is manipulated to get access to the information that is prohibited to be shared. The data may consist of numerous items, sensitive data of the company, private customer details. The impact of this attack is very severe and disruptive for the company facing it. A successful attack will cause unauthorized viewing of the customer list, vanished tables, changes in content, the behavior of the web, and sometimes the attacker tries to get access to the administration database all the above causes are very crucial for a company to run. The attacker can continuously attack the company’s system that leads to long-term damage and undergoes unnoticed for an extended period.


Many high-profile companies have faced the attack of SQL injection and seen reputational damage, regulatory fines. SQL injection takes place only because of the companies that use the application of untrusted data like web form fields. When the web page fails to clean the cache before requesting the SQL query at the same time the attacker will also execute their SQL injection that the company will execute. 


SQL injection examples – 


  • Retrieving hidden data – where you can amend the SQL query to retrieve the hidden data.
  • Subverting application logic – where you can amend the SQL query to interfere with applications logic.
  • Blind SQL injection – where the outcome of a query that is controlled by you is not returned to the application’s responses.
  • Examining the database – where you can get information about the version and structure of the database.
  • UNION attacks – where you can retrieve the data from various database tables.


Types of SQL injections 


The attacker uses the same attack with different types of SQLi for a different hotspot to crack and gain access to it.


– In-band SQLi


The attacker uses the same channel to precede the attack and gather the result. In-band SQLi is very simple and efficient and it is the most commonly used SQLi attack. 


In-band SQLi is subdivided into two parts –


  1. Error-based SQLi
  2. Union-based SQLi


Error-based SQLi – attacker takes action on the database this causes the web page to produce error messages. The attacker will be successful in gathering information about the structure database by the error messages produced. 


Union-band SQLi – it gains the advantage of the UNION SQL operator which amalgamate several statements that are generated by the database to e a single HTTP response. These responses which contain data will be purchased by the attacker.


– Inferential (Blind) SQLi


The attacker will send the web servers fake data payloads and supervise the output and behaviour of the server and learn about its structure. The data is not transferred to the attacker from the web page to the attacker’s website. 


The inferential attack depends on the responses and behaviour of the web page so they are slower to verify and be proved harmful. 


Inferential SQL can be classified into 


  1. Boolean 
  2. Time-based 


Boolean – this grants the attacker to payload fake data even though no data is returned from the database. This attack is slow, especially on large databases.


Time-based – is a technique for sending SQL query to the database which holds the database for a specified period. 


– Out-of-band SQLi


This is an alternate attack incase the in-band or inferential attacks don’t work. This attack will only work if the servers have their features enabled. This attack takes place in a situation where the attacker cannot use the same channel to make the attack and collect information or when the server is too slow or it is not suitable to perform such actions. 


Ways the attacker exploits SQLi security walls –


The attacker makes superior quality crafted input for the attack to work successfully and break the security walls. The attacker exploits the security in the below ways-


– The data that is in the database is based on the control of application behaviour. For instance, by tricking an app into login without a correct and valid password.


– Making changes in the database without any legal permission. For instance, creating fake records, promoting the user to higher levels of access, deleting data.


– Having a grant with the data without any legal authorization. For instance, manipulating the database into providing too many results for a query. 


How to detect SQLi attack –


SQLi attacks can be detected manually by the use of a specific test daily in the application. They are as follows –


– Looking for errors or others malicious and submitting the single quote character ” ‘ “.


– Using some SQL specific syntax that analysis the original value of the entry point, and the value differs too and looking for legal differences in the resulting application responses. 


– According to Booleans condition such as 1=1 or 1=2 and also looking for differences in the responses.


– Pasting fake traffic to the application for time delays when mixed up with SQLi query ad looking for different responses.


– Pasting OAST fake traffic to the application made for out-of-band network actions when verified with SQL query and monitor for any interactions.


How to Prevent from SQL Injection?


There are easy ways to defend yourself from facing SQLi attacks. They are as follows –


– Examine SQLi vulnerabilities by checking your application daily by using static resting and dynamic testing. 


– Avoid and repair SQLi vulnerability through the use of parameterized queries. You should avoid the fake queries and repair the vulnerabilities that SQLi is weak at while tackling.


– Rectify SQLi vulnerabilities in the system and tackling the inputs before them being added to the query.


– Lessen the effect of SQLi by gibing minimum privilege towards the database. Every database of application should have different passwords for keeping it safe and confidential.


– Employment of WAF is the best defence plan for getting attacked. 


– WAF can also lessen the percent of being attacked by SQLi. WAF enables a rapid response to the prevention of SQLi attacks and discloses new vulnerabilities and zero-day- threats.

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