Client-side JavaScript Vulnerabilities

Client-side JavaScript
Security vulnerabilities
The Twilight Zone of Web Application Security
Ory Segal
Security Products Architect, Rational

ORY SEGAL
Security products architect, Rational
AppScan product manager
Web Application Security Consortium officer
Contributor (WASC, MITRE, NIST, OWASP)
Renowned application security expert
AppScan

From server to client side – The migration story of web application logic

1990
<HTML>
Capable of presenting only text and hyperlinks
1993
<IMG>
Embedded images in web pages (3rd. Party allowed)
1995
<SCRIPT>
JavaScript enables programmatic modifications to HTML
1996
<IFRAME>
Embeds a page within a page (3rd party contents)
<EMBED>
Embed an Adobe Flash file for animation
1999
Client-side API (e.g. JS). Send & receive HTTP traffic programmatically, without refreshing the entire page
XHR
Fetch data asynchronously using XHR reducing the time spent waiting on page loads. Desktop app look & feel
AJAX
2005
Canvas, Media, Offline storage, D&D, Geolocation, Local SQL, …
HTML5 &
APIs
2011

Logic is Migrating from Server to Client…
We counted server-side vs. client-side LoC in popular web applications in 2005 and in 2010

Client-side JavaScript Security Issues

DOM-Based Cross-site Scripting
A type of XSS (the third type after “Reflected” & “Stored”)
Application doesn’t need to echo back user input like in Type I & Type II
We poison a DOM element, which is used in JavaScript code
Example
http://www.vuln.site/welcome.html?name=Ory
1:<HTML>2: <TITLE>Welcome!</TITLE>3: Hi4: <SCRIPT>5: var pos = document.URL.indexOf("name=") + 5;
6: document.write(document.URL.substring(pos,document.URL.length));
7: </SCRIPT> <BR/>8: Welcome to our system
9:</HTML>
Source : document.URL
Sink : document.write()
Results : document.write("Ory")

DOM-Based Cross-site Scripting
Attack Example
http://www.vuln.site/welcome.html#?name=<script>alert('hacked')</script>
1: <HTML>2: <TITLE>Welcome!</TITLE>3: Hi4: <SCRIPT>5: var pos = document.URL.indexOf("name=") + 5;
6: document.write(document.URL.substring(pos,document.URL.length));
7: </SCRIPT> <BR/>8: Welcome to our system
9: </HTML>
Sink : document.write()
Results : document.write("<script>alert('hacked')</script>")
The attack took place entirely on the client-side (# fragment identifier)
Hacker controlled DOM elements may include: document.URL, document.location, document.referrer, window.location, etc.

Client-side Open Redirect
JavaScript code automatically redirects the browser to a new location
New location is taken from a DOM element (URL, Query, Referrer, etc.)
Example
http://www.vuln.site/redirect.html?a=5&url=http://www.some.site
...
12: varsData = document.location.search.substring(1);
13: varsPos = sData.indexOf("url=") + 4;
14: varePos = sData.indexOf("&", sPos);
15: varnewURL;
16: if (ePos< 0) { newURL = sData.substring(sPos);}
17: else { newURL = sData.substring(sPos, ePos);}
18:window.location.href = newURL;
Source : document.location
Sink : window.location.href
Results : window.location.href = "http://www.some.site";

Stored DOM-Based Cross-Site Scripting
Exploiting HTML5 localStorage API
...
17: var pos = document.URL.indexOf("name=") + 5;
18: varyourName = document.URL.substring(pos,document.URL.length)
19: decodeURI(yourName);
20: window.localStorage.name = yourName;
21: }
...
welcome
register
...
3: <div id="header"></div>
4: <script>
5: varelem = document.getElementById("header");
6: varname = window.localStorage.name;
7: elem.innerHTML = "Hello, " + name;
8: </script>
...
Storage : window.localStorage.name
Sink : elem.innerHTML
Results : elem.innerHTML = <value_of_name_parameter>

So, how common are client-side JavaScript issues?

(Lack of) Statistics on Client-Side JS Issues
Two options for gathering statistics
Automated discovery
Manual discovery
Automated tools
Dynamic analysis tools only uncover ~30%
Static analysis tools struggle with dynamic code (AJAX)
Manual code review is hell – have you seen JavaScript lately?
dojo._xdReset();if(dojo["_xdDebugQueue"]&&dojo._xdDebugQueue.length>0){dojo._xdDebugFileLoaded();}else{dojo._xdNotifyLoaded();}};dojo._xdNotifyLoaded=function(){for(var _99 in dojo._xdInFlight){if(typeofdojo._xdInFlight[_99]=="boolean"){return;}}
dojo._inFlightCount=0;if(dojo._initFired&&!dojo._loadNotifying){dojo._callLoaded();}};if(typeof window!="undefined"){dojo.isBrowser=true;dojo._name="browser";(function(){var d=dojo;if(document&&document.getElementsByTagName){var _9a=document.getElementsByTagName("script");var _9b=/dojo(.xd)?.js(W|$)/i;for(vari=0;i<_9a.length;i++){varsrc=_9a[i].getAttribute("src");if(!src){continue;}var m=src.match(_9b);if(m){if(!d.config.baseUrl)
{d.config.baseUrl=src.substring(0,m.index);}varcfg=_9a[i].getAttribute("djConfig");if(cfg){var _9c=eval("({ "+cfg+" })");for(var x in _9c){dojo.config[x]=_9c[x];}}break;}}}d.baseUrl=d.config.baseUrl;var n=navigator;vardua=n.userAgent,dav=n.appVersion,
tv=parseFloat(dav);if(dua.indexOf("Opera")>=0){d.isOpera=tv;}if(dua.indexOf("AdobeAIR")>=0){d.isAIR=1;}d.isKhtml=(dav.indexOf("Konqueror")>=0)?tv:0;d.isWebKit=parseFloat(dua.split("WebKit/")[1])||undefined;d.isChrome=parseFloat(dua.split("Chrome/")[1])||undefined;d.isMac=dav.indexOf("Macintosh")>=0;var _9d=Math.max(dav.indexOf("WebKit"),dav.indexOf("Safari"),0);if(_9d&&!dojo.isChrome)
{d.isSafari=parseFloat(dav.split("Version/")[1]);if(!d.isSafari||parseFloat(dav.substr(_9d+7))<=419.3){d.isSafari=2;}}if(dua.indexOf("Gecko")>=0&&!d.isKhtml&&!d.isWebKit){d.isMozilla=d.isMoz=tv;}if(d.isMoz){d.isFF=parseFloat(dua.split("Firefox/")[1]||dua.split("Minefield/")[1])||undefined;}if(document.all&&!d.isOpera){d.isIE=parseFloat(dav.split("MSIE ")[1])||undefined;var _9e=document.documentMode;if(_9e&&_9e!=5&&Math.floor(d.isIE)!=_9e){d.isIE=_9e;}}if(dojo.isIE&&window.location.protocol==="file:") {dojo.config.ieForceActiveXXhr=true;}d.isQuirks=document.compatMode=="BackCompat";d.locale=dojo.config.locale||(d.isIE?n.userLanguage:n.language).toLowerCase();

Introducing JavaScript Security Analyzer

What is JSA?
1st and only to auto-detect client-side issues such as:
DOM-based XSS
Phishing through Open Redirect
HTML5 Notification API Phishing
HTML5 Web Storage API Poisoning
HTML5 Client-side SQL Injection
HTML5 Client-side Stored XSS
HTML5 Web Worker Script URL Manipulation
Email Attribute Spoofing
x48x65x6Cx6Cx6Fx20x57x6Fx72x6Cx64x21x48x65x6Cx6Cx6Fx20x57x6Fx72x6Cx64x21x48x65x6Cx6Cx6Fx20x57x6Fx72x6Cx64x2x48x65x6Cx6Cx6Fx20x57x6Fx72x6Cx64x21x48x65x6Cx6Cx6Fx20x57x6Fx72x6Cx64x21x48x65x6Cx6Cx6Fx20x57x6Fx72x6Cx64x21x48x65x6Cx6Cx6Fx20x57x6Fx72x6Cx64x21asiudasdfiuashdofuiashdofuiashdfoiasuhdfoasuidfhoasdufhasodfuihasodfuihasodfiuhasdofiuahsdfouiashdfouashdfoasuidhfoasiudhfasoidf[‘epqwkrqpw9k45032452309450we09f9c90asdkf0q9wkerq2w34123aspasdfoiasdpfoiasjdfpoiasjdfpoaisjdfp;asoidfjas;dfoijasd;fioajsdf;ioasjdf;aosidfja;soidfjasd;fiajsdf;asijdf;asidfjas;dfiojasd;fijdsf;oaisjdf;asifdjas;difjas;dfioajsd;foiasjdf;iasojdf;asiodfjas;dfoijasoifjpas
DE-OBFUSCATION
STRING
/* analysis */
HTML5
Analysis
Hybrid

Using JavaScript Security Analyzer
Zero configuration required
Super-simple
Super-fast

16
Viewing JSA Results in AppScan Standard
AppScan Standard – Scan Results
Vulnerable URL and line of code
Tainted data flow information

Lets try again…How common are client-side JavaScript issues?

Using JSA we ran a research on real sites
Fortune 500
175 Most popular sites
Non-obtrusive automated review
Manually verified results
Scary outcome…

14.5% Vulnerable
169,443 Total Pages
90,929 Unique Pages
1659 Pages with Vulnerabilities
Likelihood for a web page to be vulnerable is 1 : 55

Who wrote these vulnerabilities?
62%
In house
38%
3rd Party
Marketing campaign JavaScript snippets
Flash embedding JavaScript snippets
Social networking JavaScript snippets
Deep linking JavaScript libraries for Flash and AJAX applications

Issue Distribution
DOM-based XSS
Open Redirect

JavaScript is becoming prominent
Modern applications HTML5 AJAX Web2.0
Application logic is shifting to client-side
More code == more vulnerabilities
Happens when code relies on parts of the DOM that are hacker-controlled
Detection requires tedious manual work
AppScan with JSA can automate client-side issues detection

Thank You
You can download the full whitepaper at:
http://tinyurl.com/5w6koqj

Client-side JavaScript Vulnerabilities

by orysegal on Jul 28, 2011

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Client-side JavaScript Vulnerabilities — Presentation Transcript

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