Prev Next

DataStructures / System Design

What is SQL injection?

SQL injection is the highest application security concern because it's well known, easy to perform and operates on the database server.

SQL injection occurs when:

  • Malicious data is used to construct SQL statements via string concatenation, thus commingling executable code and data.
  • Executable code and data are commingled; the database server parsing the query may interpret the "data" as executable code/query. This allows the data to alter the meaning/result of the SQL query.
  • A single attack can leak an entire database, alter or destroy a database, or even lead to a compromise of the server where the database is deployed.

To mitigate the SQL injection risk:

  • Use parameterized queries with bind variables to ensure that data added to the statement cannot alter the intention of the statement.
  • Validate untrusted data; data submitted by end users.

SQL Injection example:

In the following code $user_name and $password represent variable for user input, which are then used to create a SQL statement.

SELECT * FROM BankAccounts WHERE username=$user_name AND password = $password;

A malicious user may provide input which bypasses the intended functionality of the query and which actually grants unlimited access, just by simply commenting out the "AND" portion of the SQL statement.

SELECT * FROM BankAccounts WHERE username='admin'--'AND password = 'password123';

Notice the comment indicator (--) after the username. The database will interpret the rest of the query as a comment, ignoring the password verification. The effective statement that gets executed is:

SELECT * FROM BankAccounts WHERE username='admin'

The attacker who submitted that login attempt would be granted access to resources owned by the "admin" account.

It's right time to invest in Cryptocurrencies Dogecoin! Earn free bitcoins up to $250 now by signing up.

Earn bitcoins upto $250 (free), invest in other Cryptocurrencies when you signup with blockfi. Use the referral link: Signup now and earn!

Using BlockFi, don't just buy crypto - start earning on it. Open an interest account with up to 8.6% APY, trade currencies, or borrow money without selling your assets.

Join CoinBase! We'll both receive $10 in free Bitcoin when they buy or sell their first $100 on Coinbase! Available in India also. Use the referral Join coinbase!

Invest now!!! Get Free equity stock (US, UK only)!

Use Robinhood app to invest in stocks. It is safe and secure. Use the Referral link to claim your free stock when you sign up!.

The Robinhood app makes it easy to trade stocks, crypto and more.

Webull! Receive free stock by signing up using the link: Webull signup.

More Related questions...

Difference between horizontal and vertical scaling. What is a Load Balancer? Explain few load balancing algorithms that you know. Explain CAP theorem. Explain the BASE property of the database. Explain ACID properties of database transactions. What is database sharding? Difference between database sharding and partitioning. Difference between eventual and strong consistency in Distributed Databases. How to choose between SQL and No-SQL Database? What is TLS? Explain Request Throttling. Difference: hard vs soft real-time system. What is NAT-T (NAT Traversal)? What does HLS stand for? Security measures to follow when you are developing your projects. Explain about EquiFax 2017 security incident. Different Injection defects. Different Authentication & access control defects. Causes of Data protection defects. What is Cross-site scripting? What is SQL injection? Explain Command injection. What is meant by Insecure redirects? Explain about "insecure upload/download" injection defect. What is the "Buffer overflow" attack? Differentiate Authentication and Authorization. What is parameter tampering? What is Cross-site request forgery (CSRF)? What is SACM (Service Asset and Configuration management)? What is digital accessibility? What is WAI-ARIA? What is VUI? What are Alexa skills? What is DNS TXT record? What is Resident Set Size (RSS)? Explain 12-Factor App methodology. What is certificate pinning? Difference between SSL authentication and Mutual SSL Authentication. What is OAUTH? What is a Canary release? What is Domain Driven Design? Difference between TLS and MTLS. What is RSocket? What is Site reliability engineering (SRE)? Difference Between Semaphore and Mutex. What is Privilege Escalation? What is SSRF? Best practices for Strong cryptography. Define Latency and throughput. What is Insecure Design? What is threat modeling? Explain STRIDE threat modeling. What is meant by tokenization? What is the PACELC theorem? What is a denial of service attack (DoS)? What is a Finite State Machine (FSM)? What is SNAT (Secure network address translation)? What is Global Traffic Manager (GTM)? What is Local Traffic Manager (LTM)?
Show more question and Answers...

Blockchain interview questions

Comments & Discussions