We now have two relay modules with more on the horizon. This PR adds the ability for our users to check targets for viability in the context of the modules. In the case of SMB, this checks the target has SMB signing disabled. In the case of ESC8, it checks that the target URI responds with a 401 and offers NTLM as an authentication mechanism.

Adding the check method required changes to how the modules operate. They had originally used the RELAY_TARGETS datastore option to avoid the framework splitting RHOSTS into individual RHOST options as it does for other modules types (except those that are scanners or do not register the RHOSTS option). In order for the check command to work, the RHOSTS needed to be registered, so the target to check is available to the module. For the actual exploitation though, the RHOSTS value needed to be kept as it is (e.g. a list of IP addresses, CIDR range, etc.). To support this, I added a new MultipleTargetHosts mixin that is checked for in the run command dispatcher when an Auxiliary or Exploit module is run. This check is included where the previous Scanner mixin check was included and where the datastore is checked for containing RHOSTS. With this in place, the relay modules can now uses the RHOSTS datastore option and iterate over the targets itself, while also having a check_host method that can return a check code for individual hosts. This ensures the option works consistently when the RHOSTS datastore option is set or a range is specified as an argument to the check command.

Because of where the RHOSTS string is split into individual target hosts, the MultipleTargetHosts mixin is incompatible with the AutoCheck mixin. The issue here is that the run method has the RHOSTS string without having been split and the AutoCheck mixin is incapable of splitting it and checking each host individually for exploitability. This would also introduce an ambiguity for how a case where a group of N hosts are defined and N-1 are vulnerable. Presumably, the module should fail, but it's not well equipped to report the vulnerability status of each individual host as the check command is. This seems like a reasonable limitation at this time and something that can be left alone for the time being.

Testing

• Use the auxiliary/server/relay/esc8 module
  • Set the RHOSTS option to multiple targets
  • Run the check command with no arguments, see it pulled the hosts to test from the RHOSTS datastore option
  • Run the check command with a target host argument (e.g. check 192.168.159.10-11) and see that it pulled the hosts to test from the argument
  • See that the module still works as intended
• Use the exploit/windows/smb/smb_relay module
  • Set the RHOSTS option to multiple targets
  • Run the check command with no arguments, see it pulled the hosts to test from the RHOSTS datastore option
  • Run the check command with a target host argument (e.g. check 192.168.159.10-11) and see that it pulled the hosts to test from the argument
  • See that the module still works as intended

Example

ESC8 checking:

metasploit-framework.pr (S:0 J:0) auxiliary(server/relay/esc8) > check 192.168.159.10-11
[*] 192.168.159.10:80 - The target appears to be vulnerable. Server replied that authentication is required and NTLM is supported.

[-] The host (192.168.159.11:80) was unreachable.
[*] 192.168.159.11:80 - Cannot reliably check exploitability.
metasploit-framework.pr (S:0 J:0) auxiliary(server/relay/esc8) >

SMB relay checking:

metasploit-framework.pr (S:0 J:0) exploit(windows/smb/smb_relay) > check 192.168.159.10-11
[+] 192.168.159.10 - The target is vulnerable. Signing is not required by the target server.
[*] 192.168.159.11 - Cannot reliably check exploitability. Failed to connect and negotiate an SMB connection.
metasploit-framework.pr (S:0 J:0) exploit(windows/smb/smb_relay) >