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# Copyright (C) 2017 Jakob Kreuze, All Rights Reserved.
#
# This file is part of Hypodermic.
#
# Hypodermic is free software: you can redistribute it and/or modify it
# under the terms of the GNU General Public License as published by the
# Free Software Foundation, either version 3 of the License, or (at your
# option) any later version.
#
# Hypodermic is distributed in the hope that it will be useful, but
# WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
# Public License for more details.
#
# You should have received a copy of the GNU General Public License along
# with Hypodermic. If not, see <http://www.gnu.org/licenses/>.
"""Module for generating payloads."""
from keystone import *
def assemble(code: str, arch="amd64", syntax="att") -> bytes:
"""Assembles the given assembly code.
Args:
code (str): The code to assemble
arch (:obj:`str`, optional): The target architecture.
Defaults to "amd64"
syntax (:obj:`str`, optional): The assembly syntax to use.
Defaults to "att"
Returns:
A `bytes` object containing the resultant machine code.
"""
wordlen = KS_MODE_64 if arch == "amd64" else KS_MODE_32
ks = Ks(KS_ARCH_X86, wordlen)
if syntax == "att":
ks.syntax = keystone.KS_OPT_SYNTAX_ATT
encoded, _ = ks.asm(code)
return bytes(encoded)
# FIXME: Relative addressing is untested in i386.
def open_shellcode(path: str, flags=0, arch="amd64") -> bytes:
"""Generates shellcode to open a file descriptor.
Args:
path (str): The path of the file to open.
flags (:obj:`int`, optional): Flags to pass to open. Defaults to
O_RDONLY.
arch (:obj:`str`, optional): The target architecture.
Defaults to "amd64".
Returns:
The assembled shellcode, as a `bytes` object.
"""
if arch == "amd64":
asm = " jmp __path_end;" \
"__path:" \
" .asciz \"{}\";" \
"__path_end:" \
" movq $0x02, %rax;" \
" leaq (%rip), %rdi;" \
" subq $. - __path, %rdi;" \
" movq ${}, %rsi;" \
" movq $0x00, %rdx;" \
" syscall;".format(path, flags)
else:
asm = " jmp __path_end;" \
"__path:" \
" .asciz \"{}\";" \
"__path_end:" \
" movl $0x05, %eax;" \
" call $. + 5;" \
" popl %ebx;" \
" subl $. - 4 - __path, %ebx;" \
" movl ${}, %ecx;" \
" movl $0x00, %edx;" \
" int $0x80;".format(path, flags)
return assemble(asm, arch)
def close_shellcode(fd: int, arch="amd64") -> bytes:
"""Generates shellcode to close a file descriptor.
Args:
fd (int): The file descriptor to close.
arch (:obj:`str`, optional): The target architecture.
Defaults to "amd64".
Returns:
The assembled shellcode, as a `bytes` object.
"""
if arch == "amd64":
asm = " movq $0x03, %rax;" \
" movq ${}, %rdi;" \
" syscall;".format(fd)
else:
asm = " movq $0x06, %eax;" \
" movq ${}, %ebx;" \
" int $0x80;;".format(fd)
return assemble(asm, arch)
# FIXME: Syscall number may be incorrect for i386.
def mmap_shellcode(addr=0, size=0, prot=0, flags=0, fd=-1, off=0, arch="amd64"):
"""Generates shellcode to map a region of memory.
Args:
addr (:obj:`int`, optional): The address, or 0 if unimportant.
size (:obj:`int`, optional): The desired size of the mapping.
prot (:obj:`int`, optional): The protections for the mapping.
flags (:obj:`int`, optional): Any other flags for the mapping.
fd (:obj:`int`, optional): A file descriptor to map.
off (:obj:`int`, optional): An offset in the file descriptor.
arch (:obj:`str`, optional): The target architecture.
Returns:
The assembled shellcode, as a `bytes` object.
"""
if arch == "amd64":
asm = " movq $0x09, %rax;" \
" movq ${}, %rdi;" \
" movq ${}, %rsi;" \
" movq ${}, %rdx;" \
" movq ${}, %r10;" \
" movq ${}, %r8;" \
" movq ${}, %r9;" \
" syscall;".format(addr, size, prot, flags, fd, off)
else:
asm = " movl $0x5a, %eax;" \
" movl ${}, %ebx;" \
" movl ${}, %ecx;" \
" movl ${}, %edx;" \
" movl ${}, %esi;" \
" movl ${}, %edi;" \
" movl ${}, %ebp;" \
" int $0x80;".format(addr, size, prot, flags, fd, off)
return assemble(asm, arch)
def munmap_shellcode(addr=0, size=0, arch="amd64"):
"""Generates shellcode to map a region of memory.
Args:
addr (:obj:`int`, optional): The address of the mapping.
size (:obj:`int`, optional): The size of the mapping.
arch (:obj:`str`, optional): The target architecture.
Returns:
The assembled shellcode, as a `bytes` object.
"""
if arch == "amd64":
asm = " movq $0x0b, %rax;" \
" movq ${}, %rdi;" \
" movq ${}, %rsi;" \
" syscall;".format(addr, size)
else:
asm = " movl $0x5b, %eax;" \
" movl ${}, %ebx;" \
" movl ${}, %ecx;" \
" int $0x80;".format(addr, size)
return assemble(asm, arch)
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