[R2] Dell SonicWALL /appliance/license.jsp Serial Number Disclosure Remote Privilege Escalation

While writing a detection plugin, Tenable discovered an additional vulnerability that allows a remote, unauthenticated attacker to gain admin access to the Universal Management Host (UMH) or the Universal Management Appliance (UMA) interface of a Dell SonicWALL GMS/Analyzer system.

The product is designed to allow users to reset the password of the user 'admin' to 'password'. To do so, the user must provide a valid password reset key (pwdResetKey). That key is the serial number (SN) of the product license encrypted with a key formed by concatenating the first 6 bytes of the SN and a magic string (we are not disclosing but not difficult to figure out). The encryption algorithm is 3DES using ECB mode. So the secrecy of the pwdResetKey solely depends on the SN, which is accessible without authentication via the /appliance/license.jsp script. If the product is not registered/licensed, /appliance/license.jsp will show:

[margay@wiedii sonicwall]# curl -s http://192.168.168.129/appliance/license.jsp | grep -i "Serial Number"
<td colspan=3 align=right class=bodyFont> Serial Number: <font class="controlFont">Not Registered</font> </td>

In this case, the string "password" is used for SN during pwdResetKey computation. Knowing the SN, the attacker can compute the pwdResetKey and reset the admin password to 'password'. She can then login and access the full functionalities in UMH/UMA, which includes, but not limited to, the following:

• Apply Service Packs/HotFixes to the product. This could potentially allow the attacker to upload customized/modified product files with malicious intent.
• Configure Host Role. The attacker can change the role configuration, disable/stop the services configured for the role.
• Change the password for the Administrator account (admin). The attacker can deny UMH/UMA access to legitimate users.

The pwdResetKey is validated by the com.sonicwall.appliance.servlets.AuthenticationFilter servlet.

Note that while the CVSSv2 score reflects partial integrity (e.g. manipulation of a password), the immediate follow-up impact is complete control over the software. This score is a bit misleading, but in keeping with the CVSSv2 guidelines.