/usr/lib/python2.7/dist-packages/rekall/plugins/yarascanner.py is in python-rekall-core 1.6.0+dfsg-2.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 | # Rekall Memory Forensics
# Copyright (c) 2012, Michael Cohen <scudette@gmail.com>
# Copyright (c) 2010, 2011, 2012 Michael Ligh <michael.ligh@mnin.org>
# Copyright 2013 Google Inc. All Rights Reserved.
#
# This program 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 2 of the License, or (at
# your option) any later version.
#
# This program 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 this program; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
#
"""A Rekall Memory Forensics scanner which uses yara."""
import yara
from rekall import scan
from rekall import testlib
from rekall import plugin
from rekall import utils
from rekall.plugins.common import pfn
class YaraScanMixin(object):
"""A common implementation of yara scanner.
This should be mixed with the OS specific Scanner (e.g. WinScanner) and
plugin.TypedProfileCommand.
"""
name = "yarascan"
table_header = [
dict(name="Owner", width=20),
dict(name="Rule", width=10),
dict(name="Offset", style="address"),
dict(name="hexdump", hex_width=16, width=67),
dict(name="run", hidden=True),
dict(name="address_space", hidden=True),
dict(name="Context"),
]
__args = [
dict(name="hits", default=10, type="IntParser",
help="Quit after finding this many hits."),
dict(name="string", default=None,
help="A verbatim string to search for."),
dict(name="binary_string", default=None,
help="A binary string (encoded as hex) to search "
"for. e.g. 000102[1-200]0506"),
dict(name="yara_file", default=None,
help="The yara signature file to read."),
dict(name="yara_expression", default=None,
help="If provided we scan for this yara "
"expression."),
dict(name="context", default=0x40, type="IntParser",
help="Context to print after the hit."),
dict(name="pre_context", default=0, type="IntParser",
help="Context to print before the hit."),
]
scanner_defaults = dict(
scan_physical=True
)
def __init__(self, *args, **kwargs):
"""Scan using yara signatures."""
super(YaraScanMixin, self).__init__(*args, **kwargs)
# Compile the yara rules in advance.
if self.plugin_args.yara_expression:
self.rules_source = self.plugin_args.yara_expression
self.rules = yara.compile(source=self.rules_source)
elif self.plugin_args.binary_string:
self.compile_rule(
'rule r1 {strings: $a = {%s} condition: $a}' %
self.plugin_args.binary_string)
elif self.plugin_args.string:
self.compile_rule(
'rule r1 {strings: $a = "%s" condition: $a}' %
self.plugin_args.string)
elif self.plugin_args.yara_file:
self.compile_rule(open(self.plugin_args.yara_file).read())
elif not self.ignore_required:
raise plugin.PluginError("You must specify a yara rule file or "
"string to match.")
def compile_rule(self, rule):
self.rules_source = rule
try:
self.rules = yara.compile(source=rule)
except Exception as e:
raise plugin.PluginError(
"Failed to compile yara expression: %s" % e)
def generate_hits(self, run):
for buffer_as in scan.BufferASGenerator(
self.session, run.address_space, run.start, run.end):
self.session.logging.debug(
"Scanning buffer %#x->%#x (length %#x)",
buffer_as.base_offset, buffer_as.end(),
buffer_as.end() - buffer_as.base_offset)
for match in self.rules.match(data=buffer_as.data):
for buffer_offset, name, value in match.strings:
hit_offset = buffer_offset + buffer_as.base_offset
yield match.rule, hit_offset
def collect(self):
"""Render output."""
count = 0
for run in self.generate_memory_ranges():
for rule, address in self.generate_hits(run):
count += 1
if count >= self.plugin_args.hits:
break
# Result hit the physical memory - Get some context on this hit.
if run.data.get("type") == "PhysicalAS":
symbol = pfn.PhysicalAddressContext(self.session, address)
else:
symbol = utils.FormattedAddress(
self.session.address_resolver, address,
max_distance=2**64)
yield dict(
Owner=run.data.get("task") or run.data.get("type"),
Rule=rule,
Offset=address,
hexdump=utils.HexDumpedString(
run.address_space.read(
address - self.plugin_args.pre_context,
self.plugin_args.context +
self.plugin_args.pre_context)),
Context=symbol,
# Provide the address space where the hit is reported.
address_space=run.address_space,
run=run)
class SimpleYaraScan(YaraScanMixin, plugin.TypedProfileCommand,
plugin.PhysicalASMixin, plugin.ProfileCommand):
"""A Simple plugin which only yarascans the physical Address Space.
This plugin should not trigger profile autodetection and therefore should be
usable on any file at all.
"""
name = "simple_yarascan"
__args = [
plugin.CommandOption("start", default=0, type="IntParser",
help="Start searching from this offset."),
plugin.CommandOption("limit", default=2**64, type="IntParser",
help="The length of data to search."),
]
table_header = [
dict(name="Rule", width=10),
dict(name="Offset", style="address"),
dict(name="hexdump", hex_width=16, width=67),
]
PROFILE_REQUIRED = False
def collect(self):
"""Render output."""
count = 0
address_space = self.session.physical_address_space
for buffer_as in scan.BufferASGenerator(
self.session, address_space,
self.plugin_args.start,
self.plugin_args.start + self.plugin_args.limit):
self.session.report_progress(
"Scanning buffer %#x->%#x (%#x)",
buffer_as.base_offset, buffer_as.end(),
buffer_as.end() - buffer_as.base_offset)
for match in self.rules.match(data=buffer_as.data):
for buffer_offset, _, _ in match.strings:
hit_offset = buffer_offset + buffer_as.base_offset
count += 1
if count >= self.plugin_args.hits:
break
yield dict(
Rule=match.rule,
Offset=hit_offset,
hexdump=utils.HexDumpedString(
self.session.physical_address_space.read(
hit_offset - self.plugin_args.pre_context,
self.plugin_args.context +
self.plugin_args.pre_context)))
class TestYara(testlib.SimpleTestCase):
"""Test the yarascan module."""
PARAMETERS = dict(commandline="yarascan --string %(string)s --hits 10")
|