1 1 00:00:00,600 --> 00:00:01,530 REST. 2 2 00:00:01,530 --> 00:00:04,230 In this lesson we're going to talk about REST, 3 3 00:00:04,230 --> 00:00:06,870 the Representational State Transfer. 4 4 00:00:06,870 --> 00:00:09,450 Now, REST is a software architectural style 5 5 00:00:09,450 --> 00:00:10,830 that defines a set of constraints 6 6 00:00:10,830 --> 00:00:14,040 to be used for creating web application services. 7 7 00:00:14,040 --> 00:00:15,270 When we talk about REST 8 8 00:00:15,270 --> 00:00:18,120 you also hear it referred to as RESTful APIs 9 9 00:00:18,120 --> 00:00:20,340 and these are a looser architectural framework 10 10 00:00:20,340 --> 00:00:22,920 than SOAP's tightly specified protocol. 11 11 00:00:22,920 --> 00:00:23,753 Now, if you remember 12 12 00:00:23,753 --> 00:00:26,160 we talked about SOAP used XML based messages. 13 13 00:00:26,160 --> 00:00:28,500 Well, REST has a lot more options. 14 14 00:00:28,500 --> 00:00:32,550 REST is going to support HTTP, XML, CSV 15 15 00:00:32,550 --> 00:00:34,440 which is comma separated value format 16 16 00:00:34,440 --> 00:00:36,570 or even JSON messages. 17 17 00:00:36,570 --> 00:00:37,620 All of these are messages 18 18 00:00:37,620 --> 00:00:40,200 that can be accepted and passed over REST 19 19 00:00:40,200 --> 00:00:42,930 instead of just relying on a properly formatted XML document 20 20 00:00:42,930 --> 00:00:44,460 like SOAP does. 21 21 00:00:44,460 --> 00:00:46,980 Now, let me give you an example of how this all works. 22 22 00:00:46,980 --> 00:00:49,380 If you wanted to go to my website and log into your account 23 23 00:00:49,380 --> 00:00:51,960 you would go to the domain name of diontraining.com 24 24 00:00:51,960 --> 00:00:54,090 and then go to the resource myaccount. 25 25 00:00:54,090 --> 00:00:57,060 It would look like diontraining.com/myaccount. 26 26 00:00:57,060 --> 00:01:00,660 Now, when you do this it performs an HTTP get request 27 27 00:01:00,660 --> 00:01:03,570 to receive a list of all of the courses you're enrolled in. 28 28 00:01:03,570 --> 00:01:05,610 It's also going to give you your progress or percent complete 29 29 00:01:05,610 --> 00:01:06,750 in the courses you're enrolled in 30 30 00:01:06,750 --> 00:01:09,090 and some other basic profile information. 31 31 00:01:09,090 --> 00:01:09,923 Now, on the other hand, 32 32 00:01:09,923 --> 00:01:11,310 when you start taking a quiz on my site 33 33 00:01:11,310 --> 00:01:13,230 and you click the submit button at the end, 34 34 00:01:13,230 --> 00:01:14,580 it's going to take that information 35 35 00:01:14,580 --> 00:01:16,560 as part of a RESTful API command 36 36 00:01:16,560 --> 00:01:20,790 and use the HTTP post command to send that to my server. 37 37 00:01:20,790 --> 00:01:22,350 Now, as we go through this lesson 38 38 00:01:22,350 --> 00:01:23,670 we're going to talk a little bit more 39 39 00:01:23,670 --> 00:01:25,677 about REST and RESTful APIs, 40 40 00:01:25,677 --> 00:01:26,880 and we're specifically going to talk 41 41 00:01:26,880 --> 00:01:28,860 about three major concepts. 42 42 00:01:28,860 --> 00:01:30,300 We're going to talk about OAuth, 43 43 00:01:30,300 --> 00:01:33,180 we're going to talk about OpenID Connect, or OIDC 44 44 00:01:33,180 --> 00:01:36,540 and we're going to talk about JSON Web Tokens or JWT. 45 45 00:01:36,540 --> 00:01:38,130 Now, when we talk about OAuth, 46 46 00:01:38,130 --> 00:01:40,290 this is a delegated authorization framework 47 47 00:01:40,290 --> 00:01:43,050 for RESTful APIs that enables applications 48 48 00:01:43,050 --> 00:01:46,080 to obtain limited access, also known as scopes 49 49 00:01:46,080 --> 00:01:49,920 to a user's data without giving away a user's password. 50 50 00:01:49,920 --> 00:01:51,570 Now, when you're dealing with OAuth, 51 51 00:01:51,570 --> 00:01:54,690 this is a form of authentication and authorization 52 52 00:01:54,690 --> 00:01:56,880 using this RESTful API. 53 53 00:01:56,880 --> 00:01:58,800 Now, when we talk about OAuth, 54 54 00:01:58,800 --> 00:02:01,830 this stands for the open authorization 2 protocol. 55 55 00:02:01,830 --> 00:02:03,240 It's version 2. 56 56 00:02:03,240 --> 00:02:04,860 Now, OAuth comes in two versions. 57 57 00:02:04,860 --> 00:02:05,850 There's version 1 58 58 00:02:05,850 --> 00:02:07,650 which is not commonly implemented anymore, 59 59 00:02:07,650 --> 00:02:09,510 and there's version 2. 60 60 00:02:09,510 --> 00:02:10,620 Now, notice what I said there. 61 61 00:02:10,620 --> 00:02:11,640 It's called OAuth 62 62 00:02:11,640 --> 00:02:14,580 because it's the open authorization protocol. 63 63 00:02:14,580 --> 00:02:16,590 That means this is all about authorization, 64 64 00:02:16,590 --> 00:02:18,003 not authentication. 65 65 00:02:18,870 --> 00:02:20,250 Now, when you're using OAuth 66 66 00:02:20,250 --> 00:02:22,710 it's going to serve four types of parties. 67 67 00:02:22,710 --> 00:02:25,350 You have clients, you have resource owners, 68 68 00:02:25,350 --> 00:02:26,580 you have resource servers, 69 69 00:02:26,580 --> 00:02:28,140 and you have authorization servers. 70 70 00:02:28,140 --> 00:02:31,950 Again, OAuth is for authorization. 71 71 00:02:31,950 --> 00:02:33,180 When we talk about a client, 72 72 00:02:33,180 --> 00:02:36,750 these are applications that the user wants to access or use. 73 73 00:02:36,750 --> 00:02:38,220 When we talk about the resource owners, 74 74 00:02:38,220 --> 00:02:40,950 these are the end users who are being serviced. 75 75 00:02:40,950 --> 00:02:42,570 When we talk about the resource servers, 76 76 00:02:42,570 --> 00:02:44,850 these are the servers provided by a service 77 77 00:02:44,850 --> 00:02:46,740 that the user wants to access. 78 78 00:02:46,740 --> 00:02:48,387 And then we have the authorization server. 79 79 00:02:48,387 --> 00:02:51,030 When we talk about the authorization server, 80 80 00:02:51,030 --> 00:02:53,490 we're talking about servers owned by the identity provider 81 81 00:02:53,490 --> 00:02:55,080 or the IdP. 82 82 00:02:55,080 --> 00:02:57,420 Now, how does this all work in the real world? 83 83 00:02:57,420 --> 00:02:59,460 Well, let me give you an example here. 84 84 00:02:59,460 --> 00:03:01,620 Here on the screen you'll see three columns. 85 85 00:03:01,620 --> 00:03:03,840 We have the client, the authorization servers 86 86 00:03:03,840 --> 00:03:05,370 and the resource owners. 87 87 00:03:05,370 --> 00:03:06,900 Now, this example comes from Flickr, 88 88 00:03:06,900 --> 00:03:08,340 and this is assuming you're going to be using 89 89 00:03:08,340 --> 00:03:10,350 the Flickr OAuth service. 90 90 00:03:10,350 --> 00:03:12,630 This is their version of single sign on. 91 91 00:03:12,630 --> 00:03:14,400 Now, when I talk about a client here 92 92 00:03:14,400 --> 00:03:17,160 I'm not talking about a client as in an end user. 93 93 00:03:17,160 --> 00:03:19,470 Remember my definition I just used in OAuth. 94 94 00:03:19,470 --> 00:03:20,910 A client is an application 95 95 00:03:20,910 --> 00:03:23,130 that the user wants to access or use. 96 96 00:03:23,130 --> 00:03:25,500 So, let's assume that my website 97 97 00:03:25,500 --> 00:03:27,780 was going to use Flickr single sign on 98 98 00:03:27,780 --> 00:03:29,730 as a way for you to log into it. 99 99 00:03:29,730 --> 00:03:31,170 If you wanted to get into my website 100 100 00:03:31,170 --> 00:03:33,540 you would go to my website, the application, 101 101 00:03:33,540 --> 00:03:34,980 in this case, the client, 102 102 00:03:34,980 --> 00:03:36,180 you would click on the login button 103 103 00:03:36,180 --> 00:03:38,400 and select the logon with Flickr. 104 104 00:03:38,400 --> 00:03:41,460 If you do that, you are now requesting a token. 105 105 00:03:41,460 --> 00:03:42,450 At this point, 106 106 00:03:42,450 --> 00:03:45,390 my server is going to communicate to the authorization server, 107 107 00:03:45,390 --> 00:03:47,880 going from the client to the authorization server 108 108 00:03:47,880 --> 00:03:50,460 and we are going to request that token. 109 109 00:03:50,460 --> 00:03:51,293 At that point 110 110 00:03:51,293 --> 00:03:53,340 the authorization server should give us back that token. 111 111 00:03:53,340 --> 00:03:55,140 They're going to return it to us. 112 112 00:03:55,140 --> 00:03:56,700 Now that that's happened, 113 113 00:03:56,700 --> 00:03:58,320 we're going to direct the user 114 114 00:03:58,320 --> 00:04:00,570 to go to Flickr for authorization. 115 115 00:04:00,570 --> 00:04:02,700 So you're going to get sent over to Flickr 116 116 00:04:02,700 --> 00:04:04,260 and you're going to put in your username and password 117 117 00:04:04,260 --> 00:04:05,700 on the Flickr site. 118 118 00:04:05,700 --> 00:04:07,440 At that point, Flickr server, 119 119 00:04:07,440 --> 00:04:09,180 which again is the authorization server here 120 120 00:04:09,180 --> 00:04:12,090 is going to prompt the user to provide their authorization, 121 121 00:04:12,090 --> 00:04:13,740 their username and password. 122 122 00:04:13,740 --> 00:04:16,890 Now, if you have put in the right username and password 123 123 00:04:16,890 --> 00:04:18,750 the resource owners in this case, 124 124 00:04:18,750 --> 00:04:20,490 which is the end user wanting to be serviced, 125 125 00:04:20,490 --> 00:04:21,900 in this case, you, 126 126 00:04:21,900 --> 00:04:24,570 is going to authorize applications to have access. 127 127 00:04:24,570 --> 00:04:27,420 So, you're going to get a button that says from Flickr says, 128 128 00:04:27,420 --> 00:04:29,340 diontraining.com would like to allow you 129 129 00:04:29,340 --> 00:04:31,680 to log into their site using your Flickr account 130 130 00:04:31,680 --> 00:04:33,510 and you'll say yes or no. 131 131 00:04:33,510 --> 00:04:34,343 At that point 132 132 00:04:34,343 --> 00:04:36,600 you're going to be redirected back from Flickr server, 133 133 00:04:36,600 --> 00:04:38,970 the authorization servers, to the application, 134 134 00:04:38,970 --> 00:04:42,240 that game or website, in my case, my website 135 135 00:04:42,240 --> 00:04:45,300 and that way you're going to get this OAuth verifier sent over. 136 136 00:04:45,300 --> 00:04:48,450 Now, the client, again, my application 137 137 00:04:48,450 --> 00:04:51,120 which could be a game or my website or something like that 138 138 00:04:51,120 --> 00:04:54,840 is going to exchange the required token for an access token. 139 139 00:04:54,840 --> 00:04:56,610 Once we have that access token, 140 140 00:04:56,610 --> 00:04:59,160 we're going to grant that access token over to Flickr 141 141 00:04:59,160 --> 00:05:00,780 to their authorization servers 142 142 00:05:00,780 --> 00:05:02,490 and they're going to associate that with your account. 143 143 00:05:02,490 --> 00:05:04,050 Now, anytime you log in 144 144 00:05:04,050 --> 00:05:06,510 and try to log into my service or my application 145 145 00:05:06,510 --> 00:05:07,350 using Flickr, 146 146 00:05:07,350 --> 00:05:10,020 it's going to know what rights you have on my system. 147 147 00:05:10,020 --> 00:05:12,570 And at that point, you're going to have this OAuth token 148 148 00:05:12,570 --> 00:05:14,760 that's now going to allow you to have protected access 149 149 00:05:14,760 --> 00:05:15,720 to different resources, 150 150 00:05:15,720 --> 00:05:18,600 maybe videos or quizzes or lessons or whatever it is, 151 151 00:05:18,600 --> 00:05:20,760 and then I can send those over to you, 152 152 00:05:20,760 --> 00:05:23,250 the resource owner, being the end user. 153 153 00:05:23,250 --> 00:05:24,900 That's how this works. 154 154 00:05:24,900 --> 00:05:26,220 Now, this is a little bit different 155 155 00:05:26,220 --> 00:05:28,170 than what we talked about with SOAP and SAML, 156 156 00:05:28,170 --> 00:05:29,970 but it kind of uses the same concept 157 157 00:05:29,970 --> 00:05:32,730 because OAuth was based on those things. 158 158 00:05:32,730 --> 00:05:34,380 Now, when we talk about OAuth2 159 159 00:05:34,380 --> 00:05:36,510 it is vulnerable to some attacks. 160 160 00:05:36,510 --> 00:05:37,950 For instance, it is vulnerable 161 161 00:05:37,950 --> 00:05:40,290 to a cross-site request forgery attack, 162 162 00:05:40,290 --> 00:05:42,330 and also to open redirects. 163 163 00:05:42,330 --> 00:05:43,650 This is where the attacker is going to attempt 164 164 00:05:43,650 --> 00:05:46,050 to get you as the user to click on a link 165 165 00:05:46,050 --> 00:05:49,170 so your browser will perform the actions as that user 166 166 00:05:49,170 --> 00:05:50,400 using your credentials. 167 167 00:05:50,400 --> 00:05:52,170 And so you have to be careful of these things 168 168 00:05:52,170 --> 00:05:55,560 and we've talked before about cross-site request forgeries. 169 169 00:05:55,560 --> 00:05:59,340 Now, OAuth2 is explicitly designed to authorize claims 170 170 00:05:59,340 --> 00:06:02,250 and it is not used to authenticate users. 171 171 00:06:02,250 --> 00:06:05,340 Notice, this is an authorization protocol 172 172 00:06:05,340 --> 00:06:08,700 open authorization 2, that's what it stands for, 173 173 00:06:08,700 --> 00:06:09,600 so keep that in mind. 174 174 00:06:09,600 --> 00:06:14,190 OAuth is an authorization, not an authentication platform. 175 175 00:06:14,190 --> 00:06:15,930 Now, that means if you wanted to use it 176 176 00:06:15,930 --> 00:06:18,570 you have to have some way to authenticate users too. 177 177 00:06:18,570 --> 00:06:19,770 So how are you going to do that? 178 178 00:06:19,770 --> 00:06:22,770 Well, one of the most common ways is to use OIDC 179 179 00:06:22,770 --> 00:06:24,660 which is Open ID Connect. 180 180 00:06:24,660 --> 00:06:26,790 This is an authentication protocol 181 181 00:06:26,790 --> 00:06:29,730 and it can be implemented as special types of OAuth flows 182 182 00:06:29,730 --> 00:06:32,190 with precisely defined token fields. 183 183 00:06:32,190 --> 00:06:34,560 This will allow OAuth to be used for the authorization 184 184 00:06:34,560 --> 00:06:35,790 which is what it's good for 185 185 00:06:35,790 --> 00:06:38,250 and Open ID Connect can be used for authentication 186 186 00:06:38,250 --> 00:06:39,663 which is what it's best for. 187 187 00:06:40,500 --> 00:06:42,150 Now, I know I've been throwing around the words 188 188 00:06:42,150 --> 00:06:45,000 authorization and authentication over and over again 189 189 00:06:45,000 --> 00:06:47,220 in this lesson and some previous lessons, 190 190 00:06:47,220 --> 00:06:49,290 and if it's been a while since you've done security plus 191 191 00:06:49,290 --> 00:06:50,190 you may not remember 192 192 00:06:50,190 --> 00:06:51,750 what the difference is between these two. 193 193 00:06:51,750 --> 00:06:53,970 So let me just go and take a pause here 194 194 00:06:53,970 --> 00:06:56,220 and tell you exactly what that means. 195 195 00:06:56,220 --> 00:06:57,960 When we talk about authorization, 196 196 00:06:57,960 --> 00:07:00,420 this is the function of specifying access rights 197 197 00:07:00,420 --> 00:07:02,940 and privileges to certain resources. 198 198 00:07:02,940 --> 00:07:06,180 So if you wanted to access this video lesson in the course 199 199 00:07:06,180 --> 00:07:09,240 you need to have authorization to do that. 200 200 00:07:09,240 --> 00:07:11,550 For instance, if you wanted to take this Friday off of work 201 201 00:07:11,550 --> 00:07:14,550 you need authorization from your boss to not show up. 202 202 00:07:14,550 --> 00:07:16,410 They have to give you permission. 203 203 00:07:16,410 --> 00:07:18,810 Now, if we look at authentication, 204 204 00:07:18,810 --> 00:07:20,820 this is the process of verifying the identity 205 205 00:07:20,820 --> 00:07:22,200 of a person or device. 206 206 00:07:22,200 --> 00:07:23,850 So when you go to my website 207 207 00:07:23,850 --> 00:07:25,830 and you put in your username and password, 208 208 00:07:25,830 --> 00:07:27,660 that is authentication. 209 209 00:07:27,660 --> 00:07:30,270 Once you do that, and we know who you are 210 210 00:07:30,270 --> 00:07:32,460 we then check what courses you're in 211 211 00:07:32,460 --> 00:07:33,690 and based on those courses 212 212 00:07:33,690 --> 00:07:36,930 you have the authorization to access those videos. 213 213 00:07:36,930 --> 00:07:38,520 If you signed up for this course 214 214 00:07:38,520 --> 00:07:41,760 you have the authorization to watch the CySA videos 215 215 00:07:41,760 --> 00:07:43,680 but if you didn't sign up for the pen test plus course, 216 216 00:07:43,680 --> 00:07:46,260 you can't watch those, you're not authorized. 217 217 00:07:46,260 --> 00:07:47,730 But you use the same authentication 218 218 00:07:47,730 --> 00:07:49,470 to get into the system for both, right? 219 219 00:07:49,470 --> 00:07:51,030 And so that's the difference here. 220 220 00:07:51,030 --> 00:07:52,770 Now, when we talk about OAuth, 221 221 00:07:52,770 --> 00:07:54,330 this must be paired with another tool 222 222 00:07:54,330 --> 00:07:56,100 to perform that authentication 223 223 00:07:56,100 --> 00:07:58,920 because you have to have a way to verify that identity. 224 224 00:07:58,920 --> 00:08:01,740 And again, the best way to do that is with Open ID Connect. 225 225 00:08:01,740 --> 00:08:04,230 It's one of the most popular ways of doing this. 226 226 00:08:04,230 --> 00:08:05,730 Now, the third thing we need to talk about 227 227 00:08:05,730 --> 00:08:07,470 is JSON Web Tokens. 228 228 00:08:07,470 --> 00:08:10,800 Now, when you see JWT, which stands for JSON Web Tokens 229 229 00:08:10,800 --> 00:08:14,190 this is actually pronounced as Jot like J O T 230 230 00:08:14,190 --> 00:08:16,650 but it is JSON Web Tokens. 231 231 00:08:16,650 --> 00:08:19,350 Now, this is a token format that contains a header, 232 232 00:08:19,350 --> 00:08:20,970 a payload, and a signature 233 233 00:08:20,970 --> 00:08:23,820 in the form of a JavaScript Object Notation message, 234 234 00:08:23,820 --> 00:08:25,770 which is a JSON message. 235 235 00:08:25,770 --> 00:08:28,350 Now, when you think about a JSON Web Token 236 236 00:08:28,350 --> 00:08:30,600 I want you to think about OAuth. 237 237 00:08:30,600 --> 00:08:32,430 These are used to provide authorization 238 238 00:08:32,430 --> 00:08:35,160 and specify what access rights and privileges 239 239 00:08:35,160 --> 00:08:37,290 a user would have on a system. 240 240 00:08:37,290 --> 00:08:39,570 Again, these are a form of assertion 241 241 00:08:39,570 --> 00:08:41,670 that's being made about the person, 242 242 00:08:41,670 --> 00:08:44,370 and it assumes that person has already been authenticated. 243 243 00:08:44,370 --> 00:08:48,120 So if you're using a JSON token, you're making assertions. 244 244 00:08:48,120 --> 00:08:50,730 This, again, is the authorization piece 245 245 00:08:50,730 --> 00:08:53,250 not the authentication piece. 246 246 00:08:53,250 --> 00:08:55,620 Now, if you want to see what a JSON Web Token looks like, 247 247 00:08:55,620 --> 00:08:57,270 it looks something like this. 248 248 00:08:57,270 --> 00:08:59,100 Notice, you've got some curly brackets 249 249 00:08:59,100 --> 00:09:01,530 and we have these different key pairs together. 250 250 00:09:01,530 --> 00:09:04,590 alg, h256, what do you think that means? 251 251 00:09:04,590 --> 00:09:05,580 That's an algorithm. 252 252 00:09:05,580 --> 00:09:07,020 What algorithm we're going to use 253 253 00:09:07,020 --> 00:09:09,420 to hash this and make sure it has integrity? 254 254 00:09:09,420 --> 00:09:13,380 In this case, h256, which means SHA-256. 255 255 00:09:13,380 --> 00:09:14,213 It says what type it is? 256 256 00:09:14,213 --> 00:09:17,520 In this case, a JWT, a JSON Web Token. 257 257 00:09:17,520 --> 00:09:18,770 Then you see the next set, 258 258 00:09:18,770 --> 00:09:20,340 we have sub, which is the subject. 259 259 00:09:20,340 --> 00:09:21,240 Who are we talking about? 260 260 00:09:21,240 --> 00:09:22,800 What's the ID of that person? 261 261 00:09:22,800 --> 00:09:24,840 Then we have the name, in this case, Jason. 262 262 00:09:24,840 --> 00:09:27,870 We have the email, in this case, support@diontraining.com. 263 263 00:09:27,870 --> 00:09:29,100 Now, these are just two fields 264 264 00:09:29,100 --> 00:09:31,350 that are attributes of that subject 265 265 00:09:31,350 --> 00:09:32,970 whoever that ID string is, 266 266 00:09:32,970 --> 00:09:35,910 and in this case it's Jason with support@diontraining.com. 267 267 00:09:35,910 --> 00:09:38,040 We can have lots of different fields in this, 268 268 00:09:38,040 --> 00:09:39,810 but in this case I wanted to keep it simple 269 269 00:09:39,810 --> 00:09:41,190 and just show you the basics 270 270 00:09:41,190 --> 00:09:43,920 and this would be a very, very simple JWT. 271 271 00:09:43,920 --> 00:09:46,710 Now, if you want to send this JWT over to a web server, 272 272 00:09:46,710 --> 00:09:47,970 how can you send it? 273 273 00:09:47,970 --> 00:09:50,370 Well, just like we were using with SOAP and SAML, 274 274 00:09:50,370 --> 00:09:52,470 where we can put it in as part of the url, 275 275 00:09:52,470 --> 00:09:54,300 we can do the exact same thing. 276 276 00:09:54,300 --> 00:09:58,500 Here you'll see diontraining.com/authorize, question mark, 277 277 00:09:58,500 --> 00:09:59,910 and then all that stuff in white, 278 278 00:09:59,910 --> 00:10:02,490 which is essentially base 64 encoding. 279 279 00:10:02,490 --> 00:10:05,400 We take that JWT, we encode it using base 64 280 280 00:10:05,400 --> 00:10:07,380 and we pass it as part of the url. 281 281 00:10:07,380 --> 00:10:09,330 That's a great way to get information from one place 282 282 00:10:09,330 --> 00:10:11,733 to another using JSON Web Tokens.