SLAE/exam1/compile_all.sh

75 lines
2.0 KiB
Bash
Raw Normal View History

#!/usr/bin/env sh
#
# Create shellcode with specific port
#
# Example
# ./compile_all.sh shell_bind_tcp 50123
#
# If no port specified, the default one will be used 43775
#
# Port is stored in last two bytes in HEX
#
ARG1=$1 # Specify program
ARG2=$2 # Specify port
if [ -z "$ARG1" ]; then
echo " [I] Please specify program you would like to assemble!"
echo " [I] Example: ./compile_all.sh shell_bin_tcp 50123"
exit 1;
elif ! [ -e "$ARG1".nasm ]; then
ARG1_GUESS=$(echo $ARG1 |sed 's/.nasm//g')
if [ -e "$ARG1_GUESS" ]; then
ARG1=$ARG1_GUESS
else
echo " [E] File "$ARG1".nasm does not exist!"
exit 1;
fi
fi
if ! $(grep -qi ^global $ARG1.nasm 2>/dev/null); then
echo " [E] The file "$ARG1.nasm" does not appear to be a correct NASM source!"
exit 1;
fi
echo " [+] Assembling "$1".nasm with NASM ..."
nasm -f elf32 -o $ARG1.o $ARG1.nasm && \
echo " [+] Linking "$1".o ..." && \
ld -m elf_i386 -o $ARG1 $ARG1.o && \
echo -e " [+] Generating shellcode with objdump ..." && \
SHELLCODE=$(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')
if [ -z "$ARG2" ]; then
FULL_SHELLCODE=$(echo $SHELLCODE)
else
PORT_HEX=$(printf '%.4x' $ARG2 | sed 's/../\\x&/g')
FULL_SHELLCODE=$(echo -n $SHELLCODE | sed 's/.........$//' ; echo $PORT_HEX"\"")
fi
echo -ne " [+] Shellcode size is "$(echo -ne $FULL_SHELLCODE|sed 's/\"//g'|wc -c)" bytes\n"
echo $FULL_SHELLCODE
echo " [+] Generating shellcode.c file with the "$ARG1" shellcode ..."
cat > shellcode.c << EOF
#include <stdio.h>
#include <string.h>
unsigned char code[] = \
$FULL_SHELLCODE;
main()
{
printf("Shellcode Length: %d\n", strlen(code));
int (*ret)() = (int(*)())code;
ret();
}
EOF
echo " [+] Compiling shellcode.c with GCC ..."
gcc -m32 -fno-stack-protector -z execstack shellcode.c -o shellcode
echo -e " [+] All done! You can run the shellcode now: \n$ ./shellcode"