Welcome!

Agile Computing Authors: William Schmarzo, Liz McMillan, Gopala Krishna Behara, Sridhar Chalasani, Tirumala Khandrika

Related Topics: Agile Computing, Machine Learning

Agile Computing: Article

JavaScript Hijacking: Only 1 Out 12 Popular AJAX Frameworks Prevents It

The first class of vulnerability specific to rich Web apps

JavaScript Hijacking
Web browsers enforce the Same Origin Policy to protect users from malicious Web sites. The Same Origin Policy requires that for JavaScript to access the contents of a Web page, both the JavaScript and the Web page must originate from the same domain. Without the Same Origin Policy, a malicious Web site could serve up JavaScript that loads sensitive information from other Web sites using a client's credentials, culls through it, and communicates it back to the attacker.

JavaScript Hijacking allows an attacker to bypass the Same Origin Policy in the case where a Web application uses JavaScript to communicate confidential information. The loophole in the Same Origin Policy is that it allows JavaScript from any Web site to be included and executed in the context of any other Web site. Even though a malicious site cannot directly examine any data loaded from a vulnerable site on the client, it can still take advantage of this loophole by setting up an environment that allows it to witness the execution of the JavaScript and any relevant side effects it may have. Since many Web 2.0 applications use JavaScript as a data transport mechanism, they are often vulnerable, while traditional Web applications are not.

The most popular format for communicating information in JavaScript is JavaScript Object Notation (JSON). The JSON RFC defines JSON syntax to be a subset of JavaScript object literal syntax. JSON is based on two types of data structures: arrays and objects. Any data transport format where messages can be interpreted as one or more valid JavaScript statements is vulnerable to JavaScript Hijacking. JSON makes JavaScript Hijacking easier by the fact that a JSON array stands on its own as a valid JavaScript statement. Since arrays are a natural form for communicating lists, they are commonly used wherever an application needs to communicate multiple values. Put another way, a JSON array is directly vulnerable to JavaScript Hijacking. A JSON object is only vulnerable if it is wrapped in some other JavaScript construct that stands on its own as a valid JavaScript statement.

The following example begins by showing a legitimate JSON interaction between the client and server components of a Web application that is used to manage sales leads. It goes on to show how an attacker can mimic the client and gain access to the confidential data the server returns. Note that this example, along with the rest of the examples in the article, is written for Mozilla-based browsers. Other mainstream browsers do not allow native constructors to be overridden when an object is created without the use of the new operator.

The client requests data from a server and evaluates the result as JSON with the following code:

var object;|
var req = new XMLHttpRequest();
req.open("GET", "/object.json",true);
req.onreadystatechange = function () {
if (req.readyState == 4) {
var txt = req.responseText;
object = eval("(" + txt + ")");
req = null;
}
};
req.send(null);

When the code runs, it generates an HTTP request that looks like this:

GET /object.json HTTP/1.1
...
Host: www.example.com
Cookie: JSESSIONID=F2rN6HopNzsfXFjHX1c5Ozxi0J5SQZTr4a5YJaSbAiTnRR

(In this HTTP response and the one that follows we have elided HTTP headers that are not directly relevant to this explanation.)

The server responds with an array in JSON format:

HTTP/1.1 200 OK
Cache-control: private
Content-Type: text/javascript; charset=utf-8
...
[{"fname":"Brian", "lname":"Chess", "phone":"6502135600",
"purchases":60000.00, "email":"[email protected]" },
{"fname":"Katrina", "lname":"O'Neil", "phone":"6502135600",
"purchases":120000.00, "email":"[email protected]" },
{"fname":"Jacob", "lname":"West", "phone":"6502135600",
"purchases":45000.00, "email":"[email protected]" }]

In this case, the JSON contains confidential information associated with the current user (a list of sales leads). Other users cannot access this information without knowing the user's session identifier. (In most modern Web applications, the session identifier is stored as a cookie.) However, if a victim visits a malicious Web site, the malicious site can retrieve the information using JavaScript Hijacking.

If a victim can be tricked into visiting a Web page that contains the following malicious code, the victim's lead information will be sent to the attacker's Web site (see Listing 1).

The malicious code uses a script tag to include the JSON object in the current page. The Web browser will send up the appropriate session cookie with the request. In other words, this request will be handled as though it had originated from the legitimate application.

When the JSON array arrives on the client, it will be evaluated in the context of the malicious page. To witness the evaluation of the JSON, the malicious page has redefined the JavaScript function used to create new objects. In this way, the malicious code has inserted a hook that allows it to get access to the creation of each object and transmit the object's contents back to the malicious site. Other attacks might override the default constructor for arrays instead (Grossman's Gmail exploit took this approach).

Applications that are built to be used in a mashup sometimes invoke a callback function at the end of each JavaScript message. The callback function is meant to be defined by another application in the mashup. A callback function makes a JavaScript Hijacking attack a trivial affair - all the attacker has to do is define the function. An application can be mashup-friendly or it can be secure, but it cannot be both.

If the user is not logged into the vulnerable site, the attacker can compensate by asking the user to log in and then displaying the legitimate login page for the application. This is not a phishing attack - the attacker does not gain access to the user's credentials - so anti-phishing countermeasures won't be able to defeat the attack.

More complex attacks could make a series of requests to the application by using JavaScript to dynamically generate script tags. This same technique is sometimes used to create application mashups. The only difference is that, in this mashup scenario, one of the applications involved is malicious.

Defending Against JavaScript Hijacking
First-generation Web applications are not vulnerable to JavaScript Hijacking, because they typically transmit data as part of HTML documents, not as pure JavaScript. Applications that have no secrets to keep from attackers are also trivially safe from JavaScript Hijacking attacks.

If a Web application contains an exploitable cross-site scripting vulnerability, it cannot defeat data stealing attacks such as JavaScript Hijacking, because cross-site scripting allows an attacker to run JavaScript as though it originated from the application's domain. The contra-positive does not hold - if a Web application does not contain any cross-site scripting vulnerabilities, it is not necessarily safe from JavaScript Hijacking.

For Web 2.0 applications that handle confidential data, there are two fundamental ways to defend against JavaScript Hijacking:

  1. Decline malicious requests
  2. Prevent direct execution of the JavaScript response

The best way to defend against JavaScript Hijacking is to adopt both defensive tactics.

More Stories By Yekaterina Tsipenyuk O'Neil

Yekaterina Tsipenyuk O'Neil is the founding member of the Security Research Group at Fortify Software. She is responsible for performing code audits, identifying and analyzing insecure coding patterns, providing security content for Fortify's software security products, and researching ways to improve the quality of the tools. Yekaterina has a B.S. and an M.S. in computer science from the University of California, San Diego. Her thesis work focused on mobile agent security.

More Stories By Brian Chess

Brian Chess is a founder of Fortify Software and serves as Fortify's chief scientist, where his work focuses on practical methods for creating secure systems. His book, Secure Programming with Static Analysis, shows how static source code analysis is an indispensable tool for getting security right. Brian holds a Ph.D. in computer engineering from the University of California at Santa Cruz. Before settling on security, Brian spent a decade in Silicon Valley working at huge companies and small startups. He has done research on a broad set of topics, ranging from integrated circuit design all the way to delivering software as a service.

More Stories By Jacob West

Jacob West manages Fortify Software’s Security Research Group, which is responsible for building security knowledge into Fortify's products. He brings expertise in numerous programming languages, frameworks and styles together with knowledge about how real-world systems can fail. In addition, he recently co-authored a book, "Secure Programming with Static Analysis," which was published in June 2007. Before joining Fortify, Jacob worked with Professor David Wagner, at the University of California at Berkeley, to develop MOPS (MOdel Checking Programs for Security properties), a static analysis tool used to discover security vulnerabilities in C programs. When he is away from the keyboard, Jacob spends time speaking at conferences and working with customers to advance their understanding of software security.

Comments (0)

Share your thoughts on this story.

Add your comment
You must be signed in to add a comment. Sign-in | Register

In accordance with our Comment Policy, we encourage comments that are on topic, relevant and to-the-point. We will remove comments that include profanity, personal attacks, racial slurs, threats of violence, or other inappropriate material that violates our Terms and Conditions, and will block users who make repeated violations. We ask all readers to expect diversity of opinion and to treat one another with dignity and respect.


@ThingsExpo Stories
SYS-CON Events announced today that Evatronix will exhibit at SYS-CON's 21st International Cloud Expo®, which will take place on Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. Evatronix SA offers comprehensive solutions in the design and implementation of electronic systems, in CAD / CAM deployment, and also is a designer and manufacturer of advanced 3D scanners for professional applications.
To get the most out of their data, successful companies are not focusing on queries and data lakes, they are actively integrating analytics into their operations with a data-first application development approach. Real-time adjustments to improve revenues, reduce costs, or mitigate risk rely on applications that minimize latency on a variety of data sources. In his session at @BigDataExpo, Jack Norris, Senior Vice President, Data and Applications at MapR Technologies, reviewed best practices to ...
SYS-CON Events announced today that Synametrics Technologies will exhibit at SYS-CON's 22nd International Cloud Expo®, which will take place on June 5-7, 2018, at the Javits Center in New York, NY. Synametrics Technologies is a privately held company based in Plainsboro, New Jersey that has been providing solutions for the developer community since 1997. Based on the success of its initial product offerings such as WinSQL, Xeams, SynaMan and Syncrify, Synametrics continues to create and hone inn...
"Evatronix provides design services to companies that need to integrate the IoT technology in their products but they don't necessarily have the expertise, knowledge and design team to do so," explained Adam Morawiec, VP of Business Development at Evatronix, in this SYS-CON.tv interview at @ThingsExpo, held Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA.
Recently, REAN Cloud built a digital concierge for a North Carolina hospital that had observed that most patient call button questions were repetitive. In addition, the paper-based process used to measure patient health metrics was laborious, not in real-time and sometimes error-prone. In their session at 21st Cloud Expo, Sean Finnerty, Executive Director, Practice Lead, Health Care & Life Science at REAN Cloud, and Dr. S.P.T. Krishnan, Principal Architect at REAN Cloud, discussed how they built...
No hype cycles or predictions of a gazillion things here. IoT is here. You get it. You know your business and have great ideas for a business transformation strategy. What comes next? Time to make it happen. In his session at @ThingsExpo, Jay Mason, an Associate Partner of Analytics, IoT & Cybersecurity at M&S Consulting, presented a step-by-step plan to develop your technology implementation strategy. He also discussed the evaluation of communication standards and IoT messaging protocols, data...
With tough new regulations coming to Europe on data privacy in May 2018, Calligo will explain why in reality the effect is global and transforms how you consider critical data. EU GDPR fundamentally rewrites the rules for cloud, Big Data and IoT. In his session at 21st Cloud Expo, Adam Ryan, Vice President and General Manager EMEA at Calligo, examined the regulations and provided insight on how it affects technology, challenges the established rules and will usher in new levels of diligence arou...
Smart cities have the potential to change our lives at so many levels for citizens: less pollution, reduced parking obstacles, better health, education and more energy savings. Real-time data streaming and the Internet of Things (IoT) possess the power to turn this vision into a reality. However, most organizations today are building their data infrastructure to focus solely on addressing immediate business needs vs. a platform capable of quickly adapting emerging technologies to address future ...
In his Opening Keynote at 21st Cloud Expo, John Considine, General Manager of IBM Cloud Infrastructure, led attendees through the exciting evolution of the cloud. He looked at this major disruption from the perspective of technology, business models, and what this means for enterprises of all sizes. John Considine is General Manager of Cloud Infrastructure Services at IBM. In that role he is responsible for leading IBM’s public cloud infrastructure including strategy, development, and offering m...
In his session at 21st Cloud Expo, Raju Shreewastava, founder of Big Data Trunk, provided a fun and simple way to introduce Machine Leaning to anyone and everyone. He solved a machine learning problem and demonstrated an easy way to be able to do machine learning without even coding. Raju Shreewastava is the founder of Big Data Trunk (www.BigDataTrunk.com), a Big Data Training and consulting firm with offices in the United States. He previously led the data warehouse/business intelligence and B...
The 22nd International Cloud Expo | 1st DXWorld Expo has announced that its Call for Papers is open. Cloud Expo | DXWorld Expo, to be held June 5-7, 2018, at the Javits Center in New York, NY, brings together Cloud Computing, Digital Transformation, Big Data, Internet of Things, DevOps, Machine Learning and WebRTC to one location. With cloud computing driving a higher percentage of enterprise IT budgets every year, it becomes increasingly important to plant your flag in this fast-expanding busin...
Nordstrom is transforming the way that they do business and the cloud is the key to enabling speed and hyper personalized customer experiences. In his session at 21st Cloud Expo, Ken Schow, VP of Engineering at Nordstrom, discussed some of the key learnings and common pitfalls of large enterprises moving to the cloud. This includes strategies around choosing a cloud provider(s), architecture, and lessons learned. In addition, he covered some of the best practices for structured team migration an...
22nd International Cloud Expo, taking place June 5-7, 2018, at the Javits Center in New York City, NY, and co-located with the 1st DXWorld Expo will feature technical sessions from a rock star conference faculty and the leading industry players in the world. Cloud computing is now being embraced by a majority of enterprises of all sizes. Yesterday's debate about public vs. private has transformed into the reality of hybrid cloud: a recent survey shows that 74% of enterprises have a hybrid cloud ...
22nd International Cloud Expo, taking place June 5-7, 2018, at the Javits Center in New York City, NY, and co-located with the 1st DXWorld Expo will feature technical sessions from a rock star conference faculty and the leading industry players in the world. Cloud computing is now being embraced by a majority of enterprises of all sizes. Yesterday's debate about public vs. private has transformed into the reality of hybrid cloud: a recent survey shows that 74% of enterprises have a hybrid cloud ...
DevOps at Cloud Expo – being held June 5-7, 2018, at the Javits Center in New York, NY – announces that its Call for Papers is open. Born out of proven success in agile development, cloud computing, and process automation, DevOps is a macro trend you cannot afford to miss. From showcase success stories from early adopters and web-scale businesses, DevOps is expanding to organizations of all sizes, including the world's largest enterprises – and delivering real results. Among the proven benefits,...
@DevOpsSummit at Cloud Expo, taking place June 5-7, 2018, at the Javits Center in New York City, NY, is co-located with 22nd Cloud Expo | 1st DXWorld Expo and will feature technical sessions from a rock star conference faculty and the leading industry players in the world. The widespread success of cloud computing is driving the DevOps revolution in enterprise IT. Now as never before, development teams must communicate and collaborate in a dynamic, 24/7/365 environment. There is no time to wait...
Cloud Expo | DXWorld Expo have announced the conference tracks for Cloud Expo 2018. Cloud Expo will be held June 5-7, 2018, at the Javits Center in New York City, and November 6-8, 2018, at the Santa Clara Convention Center, Santa Clara, CA. Digital Transformation (DX) is a major focus with the introduction of DX Expo within the program. Successful transformation requires a laser focus on being data-driven and on using all the tools available that enable transformation if they plan to survive ov...
SYS-CON Events announced today that T-Mobile exhibited at SYS-CON's 20th International Cloud Expo®, which will take place on June 6-8, 2017, at the Javits Center in New York City, NY. As America's Un-carrier, T-Mobile US, Inc., is redefining the way consumers and businesses buy wireless services through leading product and service innovation. The Company's advanced nationwide 4G LTE network delivers outstanding wireless experiences to 67.4 million customers who are unwilling to compromise on qua...
SYS-CON Events announced today that Cedexis will exhibit at SYS-CON's 21st International Cloud Expo®, which will take place on Oct 31 - Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. Cedexis is the leader in data-driven enterprise global traffic management. Whether optimizing traffic through datacenters, clouds, CDNs, or any combination, Cedexis solutions drive quality and cost-effectiveness. For more information, please visit https://www.cedexis.com.
SYS-CON Events announced today that Google Cloud has been named “Keynote Sponsor” of SYS-CON's 21st International Cloud Expo®, which will take place on Oct 31 – Nov 2, 2017, at the Santa Clara Convention Center in Santa Clara, CA. Companies come to Google Cloud to transform their businesses. Google Cloud’s comprehensive portfolio – from infrastructure to apps to devices – helps enterprises innovate faster, scale smarter, stay secure, and do more with data than ever before.