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123 lines
2.8 KiB
123 lines
2.8 KiB
#!/usr/bin/env sh
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#
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# Creates shell_bind_tcp shellcode with specific port
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#
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# Example
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# ./compile_all.sh shell_bind_tcp 50123
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#
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# If no port specified, the default one will be used 43775
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#
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# Port is stored in last two bytes in HEX
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#
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ARG1=$1 # Specify program
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ARG2=$2 # Specify port
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#
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# Check script usage and file existence
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#
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if [ -z "$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_bind_tcp 50123"
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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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# Port range check
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#
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if [ -z "$ARG2" ]; then
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echo " [I] Default port will be used."
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elif ! [[ $ARG2 -ge 1024 && $ARG2 -le 65535 ]]; then
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echo " [E] The port must be in range 1024..65535 !"
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exit 1;
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else
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echo " [I] Using custom port: "$ARG2
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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 "$ARG2" ]; then
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FULL_SHELLCODE=$(echo $SHELLCODE)
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else
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PORT_HEX=$(printf '%.4x' $ARG2 | sed 's/../\\x&/g')
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FULL_SHELLCODE=$(echo -n $SHELLCODE | sed 's/.........$//' ; echo $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 [[ $FULL_SHELLCODE == *00* ]]; then
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echo " [E] Your shellcode contains 00 (NULL) ! Most likely you need to change your port."
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exit 1
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fi
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echo -ne " [+] Shellcode size is "$(echo -ne $FULL_SHELLCODE|sed 's/\"//g'|wc -c)" bytes\n"
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echo $FULL_SHELLCODE
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if [ -z "$FULL_SHELLCODE" ]; then
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exit 1;
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fi
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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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