SQL injection is one of the most common ways that hackers gain access to your database. Do you know how to protect your data from malicious users? This session will provide an overview of how SQL injection works as well as steps to prevent it from happening to you. We'll examine both .NET and T-SQL solutions, as well as why some commonly used techniques aren’t as secure as many people think. If you ever capture user inputs to store in the database or write dynamic SQL queries then this session is for you.

1. SQL Injection Attacks:
Is Your Data Secure?
Cleveland C#/VB.Net User Group | Bert Wagner | February 22, 2018

2. Objective
SQL injection prevention does not have an “easy” solution

3. Disclaimers
• Try this at home
• Not at work
• Not on other people’s systems

4. Background
• Business Intelligence Developer
• Tech security enthusiast
• Saw my first injection attempts in ~2001 – MySQL logs
Demo code and slides available at bertwagner.com

5. Overview
1. Importance of SQL injection protection
2. Dynamic SQL
3. What does SQL injection look like?
4. Common misconceptions
5. Preventing SQL injection

6. • Data Leaks
• Data Validity
• Server Availability

7. Dynamic SQL
“Just because you can, doesn’t mean you should.”
• Can’t parameterize
everything
• Adaptable Queries
• Performance
However…

8. What is SQL Injection?
• Dynamic string execution
• Unsanitized input (could be from a column or parameter)
• Performing something the query wasn’t originally intended to do

9. What is SQL Injection?
Concatenating a parameter into our query string

10. What is SQL Injection?
SQL injection can occur without concatenated parameters too

11. Let’s go back to 1998…

12. OWASP 2004

13. OWASP – Present Day

14. Common Misconceptions
“The structure of my
database isn’t public”
You don’t have a Users table? Products?
Inventory? etc...
“The Amazing Bert”

15. Common Misconceptions
“I obfuscate my table names”
sys.objects? Errors displayed in app?
Logs, emails, social engineering…?

16. Common Misconceptions
“Isn’t it the DBAs job to protect the database?”
True. But multiple layers of security are better than one.
Front end validation doesn’t stop malicious users Server side validation does

17. Common Misconceptions
“I’m not important enough to get hacked”
Automated injection tools target everyone
https://github.com/sqlmapproject/sqlmap/wiki/Techniques

18. Common Misconceptions
“I use an ORM to code my SQL queries”
ORMs are still vulnerable if you need to pass an argument that can’t be
parameterized by SQL Server or if you use a vulnerable stored procedure
Other libraries, like the LINQ Dynamic Query Library, try to mitigate this but are also not perfect
https://stackoverflow.com/questions/8738953/is-injection-possible-through-dynamic-linq

19. Protecting Against SQL Injection
Must take a multi-layered approach.
Demos:
• Don’t write dynamic SQL
• sp_executesql
• QUOTENAME()
• REPLACE()
• EXECUTE AS
• Limit inputs
• Homoglyph attacks
• Proactively find injection vulnerabilities

20. Other Tools
• sqlmap
• Azure SQL
• Continuous monitoring tools
• Troy Hunt’s “hackable” website:
https://hackyourselffirst.troyhunt.com/

21. Recap
• No easy, single-approach solution
• Validate, sanitize, escape
• Developers and DBAs both responsible
• Limit executing account privileges
• Use other software to help test, find vulnerabilities

22. Thank you!
@bertwagner
bertwagner.com
youtube.com/c/bertwagner
bert@bertwagner.com
22
New posts and videos
every Tuesday!