1 00:00:00,020 --> 00:00:00,930 In this lesson, 2 00:00:00,930 --> 00:00:04,110 we're going to cover the Basics of Increasing Hash Security. 3 00:00:04,110 --> 00:00:06,600 Now, before we talk about how to increase hash security, 4 00:00:06,600 --> 00:00:08,880 we probably should focus first on two common types 5 00:00:08,880 --> 00:00:11,310 of hashing attacks that are used by threat actors. 6 00:00:11,310 --> 00:00:14,370 These are the Pass-the-Hash-Attack and the birthday attack. 7 00:00:14,370 --> 00:00:16,890 Now, first we have the Pass-the-Hash-Attack. 8 00:00:16,890 --> 00:00:19,560 Hashing is a commonly used method of storing passwords 9 00:00:19,560 --> 00:00:22,410 inside of our systems, and therefore, if the hash digest 10 00:00:22,410 --> 00:00:24,480 or hash value of that password can be obtained 11 00:00:24,480 --> 00:00:25,410 by an attacker, 12 00:00:25,410 --> 00:00:26,790 they can try to break into your network 13 00:00:26,790 --> 00:00:28,740 using those hash credentials. 14 00:00:28,740 --> 00:00:31,350 Now, the Pass-the-Hash-Attack is a hacking technique 15 00:00:31,350 --> 00:00:33,750 that allows you an attacker to authenticate to remote server 16 00:00:33,750 --> 00:00:35,970 or service by using the underlying hash 17 00:00:35,970 --> 00:00:37,080 of a user's password 18 00:00:37,080 --> 00:00:39,600 instead of actually associating the plain text password 19 00:00:39,600 --> 00:00:41,640 that you normally have to log in with. 20 00:00:41,640 --> 00:00:43,620 Now, if an attacker is able to sniff that hash 21 00:00:43,620 --> 00:00:44,880 or steal it some other way, 22 00:00:44,880 --> 00:00:46,710 they don't actually need to brute force the hash 23 00:00:46,710 --> 00:00:48,600 to try and get that clear text password 24 00:00:48,600 --> 00:00:50,310 of your giving user account. 25 00:00:50,310 --> 00:00:52,770 Instead, the attacker can simply reuse the hash 26 00:00:52,770 --> 00:00:54,330 of that arbitrary user account 27 00:00:54,330 --> 00:00:56,820 as they go and authenticate against the remote system 28 00:00:56,820 --> 00:00:59,400 and they can then impersonate the user that way. 29 00:00:59,400 --> 00:01:01,650 In other words, from an attacker's perspective, 30 00:01:01,650 --> 00:01:04,140 hashes are functioning equivalent to the original password 31 00:01:04,140 --> 00:01:05,099 that they generated, 32 00:01:05,099 --> 00:01:05,933 and this means they don't 33 00:01:05,933 --> 00:01:07,620 actually need to get the actual password 34 00:01:07,620 --> 00:01:10,320 for your account to log in as if they were you. 35 00:01:10,320 --> 00:01:12,900 The pass the hash attack is really difficult to defend 36 00:01:12,900 --> 00:01:15,030 against because there are so many possible exploits 37 00:01:15,030 --> 00:01:16,890 inside of the Windows operating system 38 00:01:16,890 --> 00:01:19,440 as well as the applications that run on top of it. 39 00:01:19,440 --> 00:01:20,340 Any of these can be used 40 00:01:20,340 --> 00:01:22,200 by an attacker to elevate their permissions 41 00:01:22,200 --> 00:01:24,240 and then be able to pull off the credential harvesting 42 00:01:24,240 --> 00:01:26,460 or hash harvesting that they can then use 43 00:01:26,460 --> 00:01:29,700 in a further attack using pass the hash technique. 44 00:01:29,700 --> 00:01:31,260 Also, only one machine 45 00:01:31,260 --> 00:01:33,240 in a Windows domain needs to be misconfigured 46 00:01:33,240 --> 00:01:34,890 or missing a critical security patch 47 00:01:34,890 --> 00:01:36,870 for that hacker to be able to find their way in 48 00:01:36,870 --> 00:01:39,870 and be able to execute this pass the hash technique. 49 00:01:39,870 --> 00:01:41,760 Now, there are many penetration tools out there 50 00:01:41,760 --> 00:01:43,800 like Mimikatz that will give you the ability 51 00:01:43,800 --> 00:01:46,410 to automate this process of harvesting the hashes 52 00:01:46,410 --> 00:01:48,660 and conducting the patch the pass the hash technique. 53 00:01:48,660 --> 00:01:50,430 To prevent the Pass-the-Hash-Attack, 54 00:01:50,430 --> 00:01:51,784 you should ensure 55 00:01:51,784 --> 00:01:52,890 that only trusted operating systems are allowed 56 00:01:52,890 --> 00:01:54,120 to connect to your servers 57 00:01:54,120 --> 00:01:56,640 that your Windows domains have their trust set up properly 58 00:01:56,640 --> 00:01:59,520 and that workstations are all going to be patched and updated 59 00:01:59,520 --> 00:02:01,590 as well as making sure your multifactor authentication 60 00:02:01,590 --> 00:02:03,060 is being used properly in your network 61 00:02:03,060 --> 00:02:05,190 and that all user accounts have been set up 62 00:02:05,190 --> 00:02:07,560 to use the concept of lease privilege. 63 00:02:07,560 --> 00:02:09,509 Now, the second type of attack I want to cover 64 00:02:09,509 --> 00:02:11,430 is what's known as a birthday attack. 65 00:02:11,430 --> 00:02:12,660 And the birthday attack occurs 66 00:02:12,660 --> 00:02:15,000 when the attacker's able to send two different messages 67 00:02:15,000 --> 00:02:16,320 through a hash algorithm 68 00:02:16,320 --> 00:02:19,110 and then get the same identical hash digest. 69 00:02:19,110 --> 00:02:20,970 This is what we call a collision. 70 00:02:20,970 --> 00:02:22,530 And in the case of a birthday attack, 71 00:02:22,530 --> 00:02:24,900 we actually are trying to create collisions. 72 00:02:24,900 --> 00:02:26,910 Now, this attack gets its name from something known 73 00:02:26,910 --> 00:02:28,350 as the Birthday paradox, 74 00:02:28,350 --> 00:02:30,630 which says that if you have a random group of people, 75 00:02:30,630 --> 00:02:32,760 the chances that you're going to have two people in that group 76 00:02:32,760 --> 00:02:35,520 with the same birthday is pretty high. 77 00:02:35,520 --> 00:02:37,760 Now, when I teach this course in person to a group 78 00:02:37,760 --> 00:02:40,380 of 30 people, most of the time two people 79 00:02:40,380 --> 00:02:42,570 in the class are going to have the same birthday 80 00:02:42,570 --> 00:02:44,280 based on the same month and day 81 00:02:44,280 --> 00:02:47,070 because there are only 365 days in a year. 82 00:02:47,070 --> 00:02:49,200 So if you actually do the math on this, 83 00:02:49,200 --> 00:02:53,100 you only need 57 people in a room to get a 99% chance 84 00:02:53,100 --> 00:02:55,230 of having two identical birthdays. 85 00:02:55,230 --> 00:02:56,910 Now, with 23 people in the room, 86 00:02:56,910 --> 00:02:58,800 your odds are about 50/50, 87 00:02:58,800 --> 00:03:00,900 and that's why in a class with about 30 students, 88 00:03:00,900 --> 00:03:03,630 more often than not we have identical birthdays 89 00:03:03,630 --> 00:03:07,020 because that puts us somewhere in the 70 to 80% range 90 00:03:07,020 --> 00:03:08,880 based on the underlying math. 91 00:03:08,880 --> 00:03:10,230 Now, in the world of hashes 92 00:03:10,230 --> 00:03:12,960 two identical hash digests are called a collision 93 00:03:12,960 --> 00:03:15,180 and if an attacker can find two identical messages 94 00:03:15,180 --> 00:03:16,380 with the same hash, 95 00:03:16,380 --> 00:03:18,960 they can use this as an attack against your system. 96 00:03:18,960 --> 00:03:21,150 For example, let's say that I found a match 97 00:03:21,150 --> 00:03:22,560 to your password's hash, 98 00:03:22,560 --> 00:03:23,520 that I can then use that 99 00:03:23,520 --> 00:03:25,380 to bypass your authentication system, 100 00:03:25,380 --> 00:03:27,390 even if I'm entering in the wrong password 101 00:03:27,390 --> 00:03:30,390 as long as that password has the same hash value. 102 00:03:30,390 --> 00:03:32,790 For this reason, we want to make sure we're using hashes 103 00:03:32,790 --> 00:03:35,310 with long output digest, so we start using things 104 00:03:35,310 --> 00:03:37,830 like SHA-256 over MD5 105 00:03:37,830 --> 00:03:39,180 because this will significantly reduce 106 00:03:39,180 --> 00:03:40,050 the amount of collisions 107 00:03:40,050 --> 00:03:42,810 and the effectiveness of a birthday attack. 108 00:03:42,810 --> 00:03:45,480 So how else can we increase the strength of our hashes, 109 00:03:45,480 --> 00:03:48,150 especially when using them as part of our password security? 110 00:03:48,150 --> 00:03:49,860 Well, one of the first things we can do 111 00:03:49,860 --> 00:03:52,140 is use something known as key stretching. 112 00:03:52,140 --> 00:03:53,610 Now, key stretching is a technique 113 00:03:53,610 --> 00:03:55,380 that's used to mitigate a weaker key 114 00:03:55,380 --> 00:03:56,700 by increasing its effectiveness 115 00:03:56,700 --> 00:03:59,730 and thereby increasing the time needed to crack that key. 116 00:03:59,730 --> 00:04:01,950 When you stretch a weaker key, the weaker key is run 117 00:04:01,950 --> 00:04:02,790 through an algorithm 118 00:04:02,790 --> 00:04:04,770 to create a longer more secure key, 119 00:04:04,770 --> 00:04:06,480 than what would normally be used. 120 00:04:06,480 --> 00:04:08,520 Many systems are going to utilize key stretching 121 00:04:08,520 --> 00:04:10,200 to increase the security they provide, 122 00:04:10,200 --> 00:04:12,630 including systems like Wifi Protected Access, 123 00:04:12,630 --> 00:04:15,600 Wifi Protected Access 2, Pretty Good Privacy 124 00:04:15,600 --> 00:04:18,180 Decrypt and others, which all use key stretching 125 00:04:18,180 --> 00:04:21,000 to mitigate a shorter keys inherent weakness. 126 00:04:21,000 --> 00:04:22,770 Second, we have salting. 127 00:04:22,770 --> 00:04:25,050 Now, salting involves the addition of random data, 128 00:04:25,050 --> 00:04:27,030 which we call a salt to the password 129 00:04:27,030 --> 00:04:30,390 before it undergoes a one-way cryptographic hash function. 130 00:04:30,390 --> 00:04:31,650 This process ensures that 131 00:04:31,650 --> 00:04:34,050 even if two users have the same password, 132 00:04:34,050 --> 00:04:36,210 their hashed outputs will be different 133 00:04:36,210 --> 00:04:38,100 because they're using different salts. 134 00:04:38,100 --> 00:04:41,310 Now, by doing so, salting amplifies password security 135 00:04:41,310 --> 00:04:43,290 and thwarts various password cracking strategies 136 00:04:43,290 --> 00:04:46,140 and techniques like dictionary attacks, brute force attacks 137 00:04:46,140 --> 00:04:47,910 and rainbow table attacks. 138 00:04:47,910 --> 00:04:50,670 Dictionary attacks happen when an attacker tries every word 139 00:04:50,670 --> 00:04:51,960 from a predefined list 140 00:04:51,960 --> 00:04:53,520 and this becomes much more challenging 141 00:04:53,520 --> 00:04:55,740 because the salt is going to alter the hash outcome 142 00:04:55,740 --> 00:04:57,930 for those commonly used passwords. 143 00:04:57,930 --> 00:05:00,480 Similarly, brute force attacks where every possible 144 00:05:00,480 --> 00:05:02,233 password combination is tested becomes 145 00:05:02,233 --> 00:05:04,290 a much more time consuming process 146 00:05:04,290 --> 00:05:06,180 because of the salting process. 147 00:05:06,180 --> 00:05:08,130 And finally, we have rainbow tables 148 00:05:08,130 --> 00:05:09,300 which are pre-computer tables 149 00:05:09,300 --> 00:05:11,370 for reversing cryptographic hash functions 150 00:05:11,370 --> 00:05:14,220 and these are rendered ineffective against salted hashes 151 00:05:14,220 --> 00:05:16,410 because the added salt forces the attackers 152 00:05:16,410 --> 00:05:17,970 to compute a new table 153 00:05:17,970 --> 00:05:20,520 for each and every salt value making this type 154 00:05:20,520 --> 00:05:22,800 of attack much more impractical. 155 00:05:22,800 --> 00:05:25,890 The third thing we have to use is what's known as nonce. 156 00:05:25,890 --> 00:05:27,960 Now, utilizing a nonce is a strategic way 157 00:05:27,960 --> 00:05:30,990 to enhance the security of potentially vulnerable passwords. 158 00:05:30,990 --> 00:05:33,450 Nonce, which stands for number used once, 159 00:05:33,450 --> 00:05:35,310 is a unique often random number 160 00:05:35,310 --> 00:05:36,143 that's going to be added 161 00:05:36,143 --> 00:05:38,340 to the password based authentication process. 162 00:05:38,340 --> 00:05:40,140 The primary function of a nonce is to ensure 163 00:05:40,140 --> 00:05:42,420 that even if the attacker is able to get your password 164 00:05:42,420 --> 00:05:44,490 or its corresponding authentication data, 165 00:05:44,490 --> 00:05:47,430 they simply can't reuse it for unauthorized access. 166 00:05:47,430 --> 00:05:48,690 By adding this transient number 167 00:05:48,690 --> 00:05:50,310 to the authentication sequence, 168 00:05:50,310 --> 00:05:52,440 your resulted hash data is going to change 169 00:05:52,440 --> 00:05:54,600 every single time and make it significantly 170 00:05:54,600 --> 00:05:58,140 harder for a cyber adversary to exploit stolen credentials. 171 00:05:58,140 --> 00:05:59,730 This ephemeral approach is going to 172 00:05:59,730 --> 00:06:01,350 add an additional layer of security, 173 00:06:01,350 --> 00:06:02,790 especially in systems that are vulnerable 174 00:06:02,790 --> 00:06:04,770 to replay attacks where the attacker attempts 175 00:06:04,770 --> 00:06:07,800 to resubmit capture data for unauthorized access. 176 00:06:07,800 --> 00:06:09,840 Finally, your systems need to be configured 177 00:06:09,840 --> 00:06:11,910 to limit the number of failed login attempts 178 00:06:11,910 --> 00:06:13,530 allowed for a giving user. 179 00:06:13,530 --> 00:06:15,480 This will help to prevent password cracking attacks 180 00:06:15,480 --> 00:06:16,950 against your accounts. 181 00:06:16,950 --> 00:06:18,150 Normally, you want the number 182 00:06:18,150 --> 00:06:19,320 of incorrect passwords entered 183 00:06:19,320 --> 00:06:20,610 before locking out the account 184 00:06:20,610 --> 00:06:23,610 to be set somewhere pretty low like three, that way, 185 00:06:23,610 --> 00:06:26,220 if somebody enters the password incorrectly three times, 186 00:06:26,220 --> 00:06:28,320 that account will automatically be locked. 187 00:06:28,320 --> 00:06:30,630 Yes, this can become painful for your users 188 00:06:30,630 --> 00:06:33,270 if they accidentally enter the wrong password to many times, 189 00:06:33,270 --> 00:06:35,324 but it does increase the security drastically 190 00:06:35,324 --> 00:06:37,740 and it does help to slow down an attacker 191 00:06:37,740 --> 00:06:39,270 who's trying to guess the user's password 192 00:06:39,270 --> 00:06:40,950 and break into your systems. 193 00:06:40,950 --> 00:06:42,840 So remember, hashing can be attacked 194 00:06:42,840 --> 00:06:44,610 through the use of pass the hash techniques 195 00:06:44,610 --> 00:06:47,220 to reuse a password without cracking its hash first 196 00:06:47,220 --> 00:06:48,930 or by using the birthday paradox 197 00:06:48,930 --> 00:06:51,750 or birthday attack to create known collisions. 198 00:06:51,750 --> 00:06:53,640 To prevent these types of hashing attacks 199 00:06:53,640 --> 00:06:54,960 you should increase your security 200 00:06:54,960 --> 00:06:57,870 of your hashing system by using key stretching, nonce 201 00:06:57,870 --> 00:07:00,330 and limiting the number of incorrect login attempts. 202 00:07:00,330 --> 00:07:02,010 Key stretching is a technique that's used 203 00:07:02,010 --> 00:07:03,870 to enhance the security of stored passwords 204 00:07:03,870 --> 00:07:06,000 by applying a hash function multiple times 205 00:07:06,000 --> 00:07:08,160 and therefore making brute force attacks 206 00:07:08,160 --> 00:07:09,420 much more time consuming 207 00:07:09,420 --> 00:07:12,180 and computationally expensive for an attacker. 208 00:07:12,180 --> 00:07:14,850 Nonces are unique values, often random numbers. 209 00:07:14,850 --> 00:07:16,290 They're going to be used once inside 210 00:07:16,290 --> 00:07:18,990 of a cryptographic operation to prevent replay attacks 211 00:07:18,990 --> 00:07:20,550 by ensuring the repeated transactions 212 00:07:20,550 --> 00:07:22,170 produce different outputs. 213 00:07:22,170 --> 00:07:23,880 And limiting the failed login attempts 214 00:07:23,880 --> 00:07:25,680 is a security measure that restricts the number 215 00:07:25,680 --> 00:07:27,000 of incorrect login attempts 216 00:07:27,000 --> 00:07:29,070 that a user can make within a given timeframe 217 00:07:29,070 --> 00:07:31,020 and the goal here is to deter attackers 218 00:07:31,020 --> 00:07:33,570 from continually guessing a user's credentials. 219 00:07:33,570 --> 00:07:35,970 By implementing these techniques, our hash digest 220 00:07:35,970 --> 00:07:38,220 and their associated data can be better protected 221 00:07:38,220 --> 00:07:39,053 from threat actors 222 00:07:39,053 --> 00:07:41,300 who may be targeting your enterprise networks.