The Western Digital My Cloud device firmware before 2.30.196 contains an authentication bypass in the network_mgr.cgi CGI module, where the "cgi_get_ipv6" command creates an admin session tied to the requester's IP address when the parameter "flag" is set to "1". An unauthenticated attacker who can reach the device over the network can send that request to create the session, then set the username=admin cookie on later requests to invoke admin-only CGI modules and gain full control of the device, with no password or user interaction required.
It was discovered that the Western Digital My Cloud device before 2.30.196 is affected by an authentication bypass vulnerability. An unauthenticated attacker can exploit this vulnerability to authenticate as an admin user without needing to provide a password, thereby gaining full control of the device. (Whenever an admin logs into My Cloud, a server-side session is created that is bound to the user's IP address. After the session is created, it is possible to call authenticated CGI modules by sending the cookie username=admin in the HTTP request. The invoked CGI will check if a valid session is present and bound to the user's IP address.) It was found that it is possible for an unauthenticated attacker to create a valid session without a login. The network_mgr.cgi CGI module contains a command called "cgi_get_ipv6" that starts an admin session -- tied to the IP address of the user making the request -- if the additional parameter "flag" with the value "1" is provided. Subsequent invocation of commands that would normally require admin privileges now succeed if an attacker sets the username=admin cookie.
Public exploit code (Metasploit) was available 21 months before disclosure.
gains valid admin session without credentials
thereby gaining full control of the device
unauthenticated network exploitation of exposed web interface
An unauthenticated attacker can exploit this vulnerability to authenticate as an admin user
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This vulnerability, registered as “CVE-2018-17153,” can allow for unauthorised actors to bypass authentication and register their activity on a specific IP address as an administrator.