Address PR feedback

Simplify the application_key usage, update docs and catch another
exception.

Author: zeroSteiner

documentation/modules/auxiliary/admin/dcerpc/samr_computer.md

@@ -14,9 +14,8 @@ computers to the domain. Administrative privileges however are required to delet
 
 ### SMBDomain
 
-The Windows domain to use for authentication. If the target server has more than one domain present on it, this option
-must be set to the target domain. If the target server has only one domain present on it, the domain will automatically
-be identified.
+The Windows domain to use for authentication. The domain will automatically be identified if this option is left in its
+default value.
 
 ### COMPUTER_NAME
 
@@ -65,14 +64,15 @@ msf6 auxiliary(admin/dcerpc/samr_computer) > show options
 
 Module options (auxiliary/admin/dcerpc/samr_computer):
 
-   Name           Current Setting  Required  Description
-   ----           ---------------  --------  -----------
-   COMPUTER_NAME                   no        The computer name
-   RHOSTS         192.168.159.96   yes       The target host(s), see https://github.com/rapid7/metasploit-framework/wiki/Using-Metasploit
-   RPORT          445              yes       The target port (TCP)
-   SMBDomain      .                no        The Windows domain to use for authentication
-   SMBPass        Password1        no        The password for the specified username
-   SMBUser        aliddle          no        The username to authenticate as
+   Name               Current Setting  Required  Description
+   ----               ---------------  --------  -----------
+   COMPUTER_NAME                       no        The computer name
+   COMPUTER_PASSWORD                   no        The password for the new computer
+   RHOSTS             192.168.159.96   yes       The target host(s), see https://github.com/rapid7/metasploit-framework/wiki/Using-Metasploit
+   RPORT              445              yes       The target port (TCP)
+   SMBDomain          .                no        The Windows domain to use for authentication
+   SMBPass            Password1        no        The password for the specified username
+   SMBUser            aliddle          no        The username to authenticate as
 
 
 Auxiliary action:

modules/auxiliary/admin/dcerpc/samr_computer.rb

@@ -115,9 +115,12 @@ def run
     @domain_sid = @samr.samr_lookup_domain(server_handle: @server_handle, name: @domain_name)
     @domain_handle = @samr.samr_open_domain(server_handle: @server_handle, domain_id: @domain_sid)
     send("action_#{action.name.downcase}")
-  rescue RubySMB::Dcerpc::Error::SamrError => e
+  rescue RubySMB::Dcerpc::Error::DcerpcError => e
     elog(e.message, error: e)
     fail_with(Failure::UnexpectedReply, e.message)
+  rescue RubySMB::Error::RubySMBError
+    elog(e.message, error: e)
+    fail_with(Failure::Unknown, e.message)
   end
 
   def random_hostname(prefix: 'DESKTOP')
@@ -164,7 +167,7 @@ def action_add_computer
         user_password: {
           buffer: RubySMB::Dcerpc::Samr::SamprEncryptedUserPasswordNew.encrypt_password(
             password,
-            @simple.client.application_key.blank? ? @simple.client.session_key : @simple.client.application_key
+            @simple.client.application_key
           )
         }
       )