def protect(self, address, permissions=None, size=0x400):
permissions = flags(permissions or 'PAGE_EXECUTE_READWRITE')
old_permissions = wintypes.DWORD()
if (m_k32.VirtualProtectEx(self.handle, address, size, permissions,
ctypes.byref(old_permissions)) == 0):
raise WindowsProcessError('Error: VirtualProtectEx',
get_last_error=m_k32.GetLastError())
return
def install_hook(self, mod_name, new_address, name=None, ordinal=None):
if not (bool(name) ^ bool(ordinal)):
raise ValueError('must select either name or ordinal, not both')
image_import_descriptors = self.get_proc_attribute('image_import_descriptor')
image_dos_header_addr = self.get_proc_attribute('image_dos_header_addr')
is_ordinal = lambda x: bool(x & 0x80000000)
for iid in image_import_descriptors:
cur_mod_name = self._get_name_for_image_import_descriptor(iid)
if cur_mod_name.lower() != mod_name.lower():
continue
ilt = self._get_ilt_for_image_import_descriptor(iid)
iat = self._get_iat_for_image_import_descriptor(iid)
for idx in range(len(ilt)):
if ilt[idx] is None:
continue
hook_it = False
if not is_ordinal(ilt[idx]) and name:
cur_func_name = self._get_name_for_ilt_entry(ilt[idx])
if cur_func_name == name:
hook_it = True
elif is_ordinal(ilt[idx]) and ordinal:
cur_func_ordinal = self._get_ordinal_for_ilt_entry(ilt[idx])
if cur_func_ordinal == ordinal:
hook_it = True
if hook_it:
old_address = iat[idx]
iat_ent_addr = image_dos_header_addr
iat_ent_addr += iid.FirstThunk
iat_ent_addr += (ctypes.sizeof(ctypes.c_void_p) * idx)
new_addr = ctypes.c_void_p()
new_addr.value = new_address
written = wintypes.DWORD()
if m_k32.WriteProcessMemory(self.handle, iat_ent_addr, ctypes.byref(new_addr), ctypes.sizeof(new_addr), ctypes.byref(written)) == 0:
errno = m_k32.GetLastError()
if errno == 998:
errno = 0
old_permissions = wintypes.DWORD()
if (m_k32.VirtualProtectEx(self.handle, iat_ent_addr, 0x400, flags('PAGE_READWRITE'), ctypes.byref(old_permissions)) == 0):
raise WindowsProcessError('Error: VirtualProtectEx', get_last_error=m_k32.GetLastError())
if m_k32.WriteProcessMemory(self.handle, iat_ent_addr, ctypes.byref(new_addr), ctypes.sizeof(new_addr), ctypes.byref(written)) == 0:
errno = m_k32.GetLastError()
self.protect(iat_ent_addr, permissions=old_permissions)
if errno:
raise WindowsProcessError('Error: WriteProcessMemory', get_last_error=errno)
hook = Hook('iat', iat_ent_addr, old_address, new_address)
self._installed_hooks.append(hook)
return hook
raise ProcessError('failed to find location to install hook')
