-: Asset Disposal. 2 2
In this lesson, we're going to talk about asset disposal, 3 3
which is critical to the physical security of your devices 4 4
and the data they process. 5 5
Asset disposal occurs whenever a system is no longer needed 6 6
by an organization. 7 7
Now, once you're done using a device like a router, 8 8
or a switch, or a firewall, 9 9
and you replace it with a newer version, 10 10
what are you going to do with that old device? 11 11
Are you simply going to take it out of the rack 12 12
and throw it in the corner? 13 13
Are you going to give it to another organization 14 14
like a charity, 15 15
or are you going to throw it away? 16 16
Well, this is really a question you have to think about 17 17
in terms of risk tolerance 18 18
and how your organization views it's security posture. 19 19
Which method you decide is going to be documented 20 20
inside your organization's disposal policy 21 21
and it's something you need to think through. 22 22
Now, regardless of which method you choose to use, 23 23
you should first make sure that you're following 24 24
your organization's policies for proper asset disposal, 25 25
because these devices may still contain valuable information 26 26
in the hands of an attacker. 27 27
For example, if you're disposing of a switch, 28 28
router or a firewall, 29 29
your old configurations may still be located 30 30
in the storage of that device. 31 31
If you throw it in the dumpster 32 32
and an attacker grabs it as part of dumpster diving, 33 33
then they're going to see every single access control rule 34 34
you have in that device 35 35
and essentially, they can map out their attacks 36 36
around your protections. 37 37
So, when it comes time to dispose of an asset, 38 38
it's important that we perform a factory reset, 39 39
wipe the configuration, or sanitize the device for disposal. 40 40
Now, many of our other network appliances 41 41
are essentially just going to be Linux servers 42 42
running specialized software. 43 43
So even our old intrusion detection systems 44 44
or intrusion protection systems, 45 45
data loss prevention systems, 46 46
and unified threat management systems 47 47
will still need to properly be disposed of 48 48
to ensure we don't let critical information 49 49
fall into the wrong hands. 50 50
For the rest of this lesson, I am going to talk specifically 51 51
about proper disposal of networking equipment 52 52
like routers and switches, 53 53
but similar processes and procedures are available 54 54
for all devices, appliances, and servers on your network. 55 55
Now, the quickest and easiest way 56 56
to prepare your devices for retirement 57 57
is to perform a factory reset. 58 58
A factory reset is a procedure 59 59
that will remove all the customer-specific data 60 60
that's been added to that network device 61 61
since the time it was shipped from the manufacturer. 62 62
This includes your IOS images, your boot images, 63 63
configurations, log files, boot variables, core files, 64 64
FIPS-related security keys, and credentials. 65 65
To perform a factory reset on a Cisco device, for example, 66 66
you simply need to enter the enable command 67 67
from the command line interface 68 68
to enter the privilege execution mode, 69 69
then enter the command factory_reset all. 70 70
Within a few minutes, you'll have a freshly-formatted 71 71
and ready to retire Cisco router or switch. 72 72
Now, on the other hand, 73 73
if you only need to perform a wipe of your configurations, 74 74
you can do this on a Cisco device 75 75
using the write erase command. 76 76
This will raise the NVRAM file system, 77 77
and will remove both the running 78 78
and startup configuration files. 79 79
But when you use either of these two options, 80 80
you're essentially just running a format command 81 81
on the storage of these switches. 82 82
If you're a bit more paranoid 83 83
or you're dealing with a high security environment, 84 84
you should take the extra step 85 85
of sanitizing your devices for disposal. 86 86
Now, the challenge is that sensitization procedures 87 87
usually involve conducting a format 88 88
and overwriting the non-volatile memory or storage 89 89
with a series of randomized ones or zeros multiple times 90 90
in order to prevent any reconstruction of the data remnants 91 91
from the storage devices. 92 92
So if you're using a network appliance 93 93
that's essentially a Linux workstation, 94 94
you can follow the standard overwrite procedures 95 95
for sanitization of hard drives and solid state drives 96 96
that you learned back in A+. 97 97
But unfortunately, if you're using a router or a switch, 98 98
this may not be possible. 99 99
In those cases, you have to resort to the removal 100 100
and physical destruction of the NVRAM and the flash modules 101 101
from these devices. 102 102
The NVRAM module stores your configuration files 103 103
and the flash module stores the Cisco IOS, 104 104
both of these are removable 105 105
on most Cisco routers and switches. 106 106
So you can take them out and destroy them. 107 107
If you happen to work for the government or the military 108 108
on a classified system, 109 109
they will usually go to this level of effort 110 110
to sanitize and destroy the NVRAM and flash modules 111 111
prior to disposal, recycling or destruction 112 112
of their secret and top secret routers and switches. 113 113
That said, most businesses and organizations 114 114
are instead going to rely on a factory reset 115 115
or simply wiping the configurations 116 116
prior to disposing of the devices. 117 117
Now, when it comes to disposing of the information 118 118
from our systems, 119 119
we have some other methods that we can use as well. 120 120
For example, if you have a bunch of backup tapes 121 121
that need to be disposed of, 122 122
you can actually shred those tapes 123 123
by pulling the magnetic ribbons out of the casing, 124 124
and then you can put them through the shredder, 125 125
or you can even burn them 126 126
as a method of physical destruction. 127 127
If your organization is using hard drives for storage, 128 128
these can be destroyed using a degaussing process. 129 129
Degaussing is going to expose the hard disk 130 130
to a powerful magnetic field 131 131
and this causes the previously written data 132 132
to be wiped from the drive 133 133
and the drive becomes a blank slate once again. 134 134
Now, I've also seen organizations 135 135
that take this a step further 136 136
and they physically destroy those hard drives 137 137
to prevent the data from being exposed. 138 138
And they do this by hitting them with axes, 139 139
smashing them with hammers, 140 140
or even using industrial shredders 141 141
to turn that hard disk into tiny little pieces. 142 142
Now, if all that sounds a little too violent for you, 143 143
that's okay, 144 144
there's electronic mechanisms to do this as well. 145 145
This is known as purging or sanitizing. 146 146
Now purging or sanitizing is the act of removing data 147 147
in such a way that it can not be reconstructed 148 148
using any known forensic techniques. 149 149
This includes using special bit by bit erasing software 150 150
that can allow you to rewrite the hard drive many times over 151 151
with a series of ones and zeros. 152 152
If you do this seven times or 35 times 153 153
for really high security applications, 154 154
you can actually erase that drive and reuse it again. 155 155
Another technique you can use is to encrypt the drive. 156 156
And if you destroy the encryption key, 157 157
this again makes the data on that drive impossible to read, 158 158
that's another way to basically sanitize your drive. 159 159
Now, if you want to reuse that old hard drive 160 160
more easily, though, 161 161
you would instead use a clearing technique. 162 162
Now, a clearing technique is the removal of data 163 163
with a certain amount of assurance 164 164
that it can't be reconstructed. 165 165
For example, 166 166
if you delete a file or folder from your hard disk, 167 167
and then you replace that area that it was stored on 168 168
with a series of zeros, this would constitute clearing. 169 169
This is also used to do a secure erase function 170 170
inside of some operating systems. 171 171
Now, unfortunately, clearing is not foolproof 172 172
and with special forensic techniques and procedures, 173 173
you can actually recover that data, 174 174
but again, it's a very low likelihood. 175 175
Also, if you want to conduct something 176 176
like a low level format of a hard disk, 177 177
this could be considered clearing as well. 178 178
The bottom line is, 179 179
if you're working in a high security environment, 180 180
you really shouldn't be using clearing. 181 181
Instead, you should opt for purging or physical destruction. 182 182
Now, when it comes down to it, 183 183
the major security concern here that we're dealing with 184 184
is data remnants. 185 185
These are the leftover pieces of the data 186 186
that may exist on the hard drive that we no longer needed. 187 187
For example, let's say I took an old network appliance 188 188
that runs on a Linux server, 189 189
and I want to sell it to another person, 190 190
I would want to ensure that they can't access any of the data 191 191
that was previously stored on there, right? 192 192
Well, to do that, I can remove the hard drive, 193 193
but this would make that network appliance 194 194
essentially unusable or unsellable. 195 195
So instead, I can purge it or sanitize it 196 196
by going through and using the overwrite procedures 197 197
and then re-install the operating system 198 198
for this appliance and all of the software 199 199
as if I just received it from the factory again. 200 200
As long as I overwrote every single sector 201 201
of that hard drive multiple times, 202 202
the fear of the data being recovered would be mitigated. 203 203
Now, there is no right or wrong answer 204 204
when it comes to deciding 205 205
if an asset should be physically destroyed or reused. 206 206
This is a decision you have to make 207 207
as a cybersecurity professional based on the cost, 208 208
the business case and the security issues 209 209
that are involved in your organization 210 210
and based on its asset disposal policies. 211 211
(gentle electronic music)