mirror of
https://github.com/volatilityfoundation/volatility
synced 2026-06-08 18:04:46 +00:00
Andrew C
110 lines
5.0 KiB
Python
110 lines
5.0 KiB
Python
# Volatility
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# Copyright (C) 2007-2013 Volatility Foundation
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#
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# This file is part of Volatility.
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#
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# Volatility 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 2 of the License, or
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# (at your option) any later version.
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#
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# Volatility 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 Volatility. If not, see <http://www.gnu.org/licenses/>.
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#
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# based on the plugin described by Cem Gurkok at:
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# http://siliconblade.blogspot.co.uk/2013/07/back-to-defense-finding-hooks-in-os-x.html
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"""
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@author: Andrew Case
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@license: GNU General Public License 2.0
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@contact: atcuno@gmail.com
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@organization:
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"""
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import distorm3
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import volatility.obj as obj
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import volatility.plugins.mac.common as common
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import volatility.debug as debug
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class mac_check_syscall_shadow(common.AbstractMacCommand):
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""" Looks for shadow system call tables """
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# https://github.com/siliconblade/volatility/blob/master/mac/check_hooks.py#L216
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def shadowedSyscalls(self, model, distorm_mode, sysents_addr):
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#looks like these syscall functions end with a call to _thread_exception_return
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thread_exc_ret_addr = self.addr_space.profile.get_symbol('_thread_exception_return')
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prev_op = None
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sysent_funcs = ['_unix_syscall_return', '_unix_syscall64', '_unix_syscall']
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for func in sysent_funcs:
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func_addr = self.addr_space.profile.get_symbol(func)
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content = self.addr_space.read(func_addr, 1024)
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for op in distorm3.Decompose(func_addr, content, distorm_mode):
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if not op.valid:
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break
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if op.mnemonic == "CALL" and op.operands[0].value == thread_exc_ret_addr:
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break
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if model == "64bit":
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#callp = &sysent[63] OR &sysent[code] OR callp == sysent
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if op.mnemonic in ['ADD','CMP'] and op.operands[0].type == 'Register' and op.operands[0].name in ["RSP","RBX","R12","R13","R14","R15"] and 'FLAG_RIP_RELATIVE' in op.flags:
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#compare actual sysent tbl address to the one in the instruction, calculated per distorm3 INSTRUCTION_GET_RIP_TARGET
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op_sysent_ptr = obj.Object('Pointer', offset = (op.address + op.operands[1].disp + op.size), vm = self.addr_space)
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if sysents_addr != op_sysent_ptr.v():
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print "not same: %x | %x" % (sysents_addr, op_sysent_ptr.v())
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yield (op_sysent_ptr.v(), func, op)
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elif model == "32bit":
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#LEA EAX, [EAX*8+0x82ef20]
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if op.mnemonic == 'LEA' and op.operands[0].type == 'Register' and op.operands[0].name in ['EDI','EAX'] and distorm3.Registers[op.operands[1].index] == "EAX" and op.operands[1].scale == 8:
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if op.operands[1].disp != sysents_addr:
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shadowtbl_addr = op.operands[1].disp
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yield (shadowtbl_addr, func, op)
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break
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#CMP EAX, 0x82ef20
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elif op.mnemonic == 'CMP' and op.operands[0].type == 'Register' and op.operands[0].name in ['EDI','EAX'] and prev_op.mnemonic in ['LEA','MOV'] and self.addr_space.is_valid_address(op.operands[1].value) == True:
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if op.operands[1].value != sysents_addr:
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shadowtbl_addr = op.operands[1].value
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yield (shadowtbl_addr, func, op)
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#CMP DWORD [EBP-0x20], 0x82ef20
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elif op.mnemonic == 'CMP' and op.operands[0].index != None and distorm3.Registers[op.operands[0].index] == "EBP" and op.operands[0].disp == -32 and op.operands[0].type == "Immediate":
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if op.operands[1].value != sysents_addr:
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shadowtbl_addr = op.operands[1].value
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yield (shadowtbl_addr, func, op)
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prev_op = op
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def calculate(self):
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common.set_plugin_members(self)
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model = self.addr_space.profile.metadata.get('memory_model', 0)
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if model == '32bit':
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distorm_mode = distorm3.Decode32Bits
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else:
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distorm_mode = distorm3.Decode64Bits
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for (shadowtbl_addr, func, op) in self.shadowedSyscalls(model, distorm_mode, self.addr_space.profile.get_symbol("_sysent")):
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yield (shadowtbl_addr, func, op)
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def render_text(self, outfd, data):
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self.table_header(outfd,
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[("Hooked Function", "30"),
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("Hook Address", "[addrpad]"),
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("Instruction", "")])
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for (shadowtbl_addr, func, op) in data:
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self.table_row(outfd, func, shadowtbl_addr, op)
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