Autopsy  4.19.3
Graphical digital forensics platform for The Sleuth Kit and other tools.
BitlockerDetection.java
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1 /*
2  * Autopsy Forensic Browser
3  *
4  * Copyright 2018 Basis Technology Corp.
5  * Contact: carrier <at> sleuthkit <dot> org
6  *
7  * Licensed under the Apache License, Version 2.0 (the "License");
8  * you may not use this file except in compliance with the License.
9  * You may obtain a copy of the License at
10  *
11  * http://www.apache.org/licenses/LICENSE-2.0
12  *
13  * Unless required by applicable law or agreed to in writing, software
14  * distributed under the License is distributed on an "AS IS" BASIS,
15  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
16  * See the License for the specific language governing permissions and
17  * limitations under the License.
18  */
19 package org.sleuthkit.autopsy.modules.encryptiondetection;
20 
21 import org.sleuthkit.datamodel.TskCoreException;
22 import org.sleuthkit.datamodel.Volume;
23 
28 final class BitlockerDetection {
29 
30  private static final int BITLOCKER_BIOS_PARAMETER_BLOCK_SIZE = 0x54;
31  private static final byte[] BITLOCKER_SIGNATURE_BYTES = {'-', 'F', 'V', 'E', '-', 'F', 'S', '-'};
32  private static final int BITLOCKER_ADDRESS_SIGNATURE = 0x3;
33  private static final int BITLOCKER_ADDRESS_SECTORS_PER_CLUSTER = 0xD;
34  private static final int BITLOCKER_ADDRESS_RESERVED_CLUSTERS = 0xE;
35  private static final int BITLOCKER_ADDRESS_FAT_COUNT = 0x10;
36  private static final int BITLOCKER_ADDRESS_ROOT_ENTRIES = 0x11;
37  private static final int BITLOCKER_ADDRESS_SECTORS = 0x13;
38  private static final int BITLOCKER_ADDRESS_SECTORS_PER_FAT = 0x16;
39  private static final int BITLOCKER_ADDRESS_LARGE_SECTORS = 0x20;
40 
44  private BitlockerDetection() {
45  }
46 
57  static boolean isBitlockerVolume(Volume volume) throws TskCoreException {
58  /*
59  * Logic in this method is based on
60  * https://blogs.msdn.microsoft.com/si_team/2006/10/26/detecting-bitlocker/
61  */
62 
63  boolean bitlockerVolume = false;
64 
65  byte[] bpbArray = new byte[BITLOCKER_BIOS_PARAMETER_BLOCK_SIZE];
66  volume.read(bpbArray, 0, BITLOCKER_BIOS_PARAMETER_BLOCK_SIZE);
67 
68  boolean signatureMatches = true;
69  for (int i = 0; i < BITLOCKER_SIGNATURE_BYTES.length; i++) {
70  if (bpbArray[BITLOCKER_ADDRESS_SIGNATURE + i] != BITLOCKER_SIGNATURE_BYTES[i]) {
71  signatureMatches = false;
72  break;
73  }
74  }
75 
76  if (signatureMatches) {
77  switch ((int) bpbArray[BITLOCKER_ADDRESS_SECTORS_PER_CLUSTER]) {
78  case 0x01:
79  case 0x02:
80  case 0x04:
81  case 0x08:
82  case 0x10:
83  case 0x20:
84  case 0x40:
85  case 0x80:
86  short reservedClusters
87  = (short) ((bpbArray[BITLOCKER_ADDRESS_RESERVED_CLUSTERS] << 8)
88  | (bpbArray[BITLOCKER_ADDRESS_RESERVED_CLUSTERS + 1] & 0xFF));
89  byte fatCount
90  = bpbArray[BITLOCKER_ADDRESS_FAT_COUNT];
91  short rootEntries
92  = (short) ((bpbArray[BITLOCKER_ADDRESS_ROOT_ENTRIES] << 8)
93  | (bpbArray[BITLOCKER_ADDRESS_ROOT_ENTRIES + 1] & 0xFF));
94  short sectors
95  = (short) ((bpbArray[BITLOCKER_ADDRESS_SECTORS] << 8)
96  | (bpbArray[BITLOCKER_ADDRESS_SECTORS + 1] & 0xFF));
97  short sectorsPerFat
98  = (short) ((bpbArray[BITLOCKER_ADDRESS_SECTORS_PER_FAT] << 8)
99  | (bpbArray[BITLOCKER_ADDRESS_SECTORS_PER_FAT + 1] & 0xFF));
100  int largeSectors
101  = ((bpbArray[BITLOCKER_ADDRESS_LARGE_SECTORS] << 24)
102  | ((bpbArray[BITLOCKER_ADDRESS_LARGE_SECTORS + 1] & 0xFF) << 16)
103  | ((bpbArray[BITLOCKER_ADDRESS_LARGE_SECTORS + 2] & 0xFF) << 8)
104  | (bpbArray[BITLOCKER_ADDRESS_LARGE_SECTORS + 3] & 0xFF));
105 
106  if (reservedClusters == 0 && fatCount == 0 && rootEntries == 0
107  && sectors == 0 && sectorsPerFat == 0 && largeSectors == 0) {
108  bitlockerVolume = true;
109  }
110 
111  break;
112 
113  default:
114  // Invalid value. This is not a Bitlocker volume.
115  }
116  }
117 
118  return bitlockerVolume;
119  }
120 }

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