DNS data transfer tool - bash

scavenger.sh

#!/bin/bash
OPTIND=1
function cleanup {
clear
sleep 4
if [[ $arg != *"-v"* ]]; then
	echo "Cleaning up this mess..."
	rm -f ./.temp2
	rm -f ./temp1.pcap
	rm -f ./.temp1
	rm -f ./pcap
	clear
else
	echo "Leaving a mess (verbose)..."
	echo "Clean it up before you run the file again --- ls -al"
	echo ""
fi
exit
}
function timecount {
if [[ $stdin == "true" ]]; then
        tput cup 0 0
        echo "Unable to estimate stream completion time... "
else
declare -i size=$(du -b $file | cut -f1)
declare -i num=$(expr $size \* 2 \* 2 / 96)     #2 secs per 96 byte query, * 2 queries
#declare -i sec=$(expr $size % 60)
#declare -i min=$(expr $totalsec / 60)

declare -i min=0
declare -i hour=0
declare -i day=0
    if((num>59));then
        ((sec=num%60))
        ((num=num/60))
        if((num>59));then
            ((min=num%60))
            ((num=num/60))
            if((num>23));then
                ((hour=num%24))
                ((day=num/24))
            else
                ((hour=num))
            fi
        else
            ((min=num))
        fi
    else
        ((sec=num))
    fi
    tput cup 0 0
    echo -ne "Current Date & Time: $(date)  Est. Completion Time in: "
    echo "$day"d "$hour"h "$min"m "$sec"s
fi
}
function dnstransfer {
        if [[ "$arg" != *-f* ]] || [[ "$arg" != *-q* ]] || [[ "$arg" != *-s* ]] || [[ "$arg" != *-d* ]]; then
                echo "Not enough flags/switches"
                echo "Run the -h command to view the help file"
                echo "Required flags: f,d,q,s,t"
                exit
        else
	clear
        base64 -w 63 $file > ./.temp1
        echo 'EOF' >> ./.temp1		#comment this out if you do not want to add the EOF line; use Ctrl-C to exit receiver loop
        sed -i 's/+/?/g' ./.temp1
	clear;timecount &
	while IFS= read -r line || [ -n "$line" ]; do
	trap "break;cleanup" 1 2
	tput cup 1 0
	dig +tries=2 +time=$timeout @$serverip $line.$domain
	done < ./.temp1
        fi
cleanup
exit
}
function dnsreceive {
        if [[ "$arg" != *-i* ]] || [[ "$arg" != *-f* ]] || [[ "$arg" != *-p* ]] || [[ "$arg" != *-d* ]]; then
                echo "Not enough flags/switches"
                echo "Required flags: i,f,p,d,r"
                echo "Run the -h command to view the help file"
                exit
        else
                echo "Press CTRL-C when EOF reached"
                echo "Starting the packet capture...scanning for EOF marker"
                echo ""; echo "Your file will be located here: ./"$file""; echo "";
                tcpdump -i $iface port 53 and host $host -l -n -s 0 > ./pcap &
                while true; do
                        if tail -f -n 1 pcap | grep -m 1 --line-buffered EOF; then
                                kill -2 $(ps aux | grep tcpdump | grep -v "grep tcpdump" | awk '{print $2}') > /dev/null
                                echo "EOF reached...starting cleanup!"
                                sleep 3
                                grep $host pcap | grep $domain pcap | cut -d ' ' -f 9 | cut -d '.' -f 1 | uniq | sed -e 's/\(EOF\)*$//g' > ./.temp2
                                break
                        fi
                done
                sed -i 's/?/+/g' ./.temp2
                base64 -d ./.temp2 > $file
                cleanup
                exit

	fi
}
function helpmenu {
echo "
+++++++++++++++++Scavenger: DNS File Transfer and Receiving+++++++++++++++++
-h  -----  This help mess
-v  -----  verbose mode
-z  -----  version/about
*************Transmit Options*************
-t  -----  You want to set up file transfer via the DNS protocol
-f  -----  The input file to transfer; also takes in stdin '-'.  See example.
-d  -----  The domain to use as the lookup string
-q  -----  The timeout delay (sec) between DNS queries
-s  -----  Destination server IP address
*************Receive Options*************
-r  -----  You want to receive a file transfer via the DNS protocol
-p  -----  Host IP sending the data
-i  -----  Listening interface
-d  -----  The domain to look for in the DNS traffic
-f  -----  The name to save the file as
Examples:
----|Transfer|----
Required flags: f,d,q,s,t
scavenger -f [inputfile] -d [domain] -q [dns query delay] -s [destination server IP] -t
scavenger -f ./stegofile.jpg -d cyber.com -q 5 -s 8.8.8.8 -t
echo "secret message" | ./scavenger -f - -d cyber.com -q 0 -s 8.8.8.8 -t
----|Receiver (On 8.8.8.8 machine from previous ex.)|---- 
Required flags: i,f,p,d,r
scavenger -i [listening interface] -f [save-as name] -p [sender IP] -d [domain to listen for] -r
scavenger -i eth0 -f ./stegofile.jpg -p 10.0.1.5 -d cyber.com -r
Note1: You must have a receiver setup on the destination server's side to catch the DNS queries,
prior to sending the traffic.
Note2: You may need to preceed the script with sudo.
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++"
}
function versioninfo {
echo "
*****************Scavenger*****************
Scavenger is a script that leverages base64 encoding to transmit
contents via the DNS protocol.
Scavenger v1.0.6 Copyright (C) 2015 
This program comes with ABSOLUTELY NO WARRANTY;
This is free software, and you are welcome to redistribute it
under certain conditions
Last Updated: 10/12/2015
"
exit
}
arg="$*"
NUMARGS="$#"
if [[ $arg == *"-v"* ]]; then
	echo "Number of arguments: $NUMARGS"
	echo "Arguments entered: $arg"
fi
if [[ "$*" == *"-r"* ]] && [[ "$*" == *"-t"* ]]; then
	echo "
	=======================================================================
	ERROR: You can only select -t OR -r NOT both, that wouldn't make sense.
	======================================================================="
	echo "Try -h for the help menu"
	exit
fi
if [ $NUMARGS -eq 0 ]; then
  helpmenu
fi
while getopts "zhf:d:q:s:p:i:vtr" option;
do
	case $option in	
	h|\?) helpmenu
	exit;;
        f)      if [[ "$OPTARG" = "-" ]]; then
                        file="${VAR:-/dev/stdin}"
                        stdin="true"
                else
                        file="$OPTARG"
                fi;;
	d) domain="$OPTARG";;
	q) timeout="$OPTARG";;
	s) serverip="$OPTARG";;
	p) host="$OPTARG";;
	i) iface="$OPTARG";;
	v) verbose=true;;
	t) dnstransfer;;
	r) dnsreceive;;
	z) versioninfo;;
esac
done
shift $((OPTIND-1))