HITB ezine issue 6 2011 - Tài liệu text

incorrect fashion.

AV 7 - Sandbox attacks and
ClickJacking
ClickJacking or UI regressing is an interesting vector
emerging on the net. After the introduction of social
networking sites, it seems to have become a popular attack
vector to cause malicious events from legitimate sessions.
HTML 5 allows various ways of enhancing the GUI inside
a browser. HTML 5 has brought along the introduction
of new tags like canvas. CSS enhancement ability allows
ClickJacking attack vectors to be formed relatively easily.
Also browsers have introduced the sandboxing ability
which allows reverse ClickJacking where an attacker can
load his domain on the frame, being on the same domain,

by leveraging vulnerabilities like XSS. It allows the attacker
to stay persistently on the site and monitor all moves
made by the end user as well as retrieve information from
his session.

It is possible to transfer malicious code at the point of the
event.

AV 9 - Botnet/Spynet gets persistent
life using WebWorkers
WebWorkers are a new introduction in the specification.
This functionality allows the browser to run scripts in the
background along with the main page. This effectively
makes the browser similar to a multithreaded application
and one can leverage this method.

In many applications one can inject a Widget or a Gadget.
This little HTML code along with JavaScript runs on the
If the application is using JavaScript driven frame-bursting DOM and performs several operations. In some cases
solution to protect against ClickJacking then the above these Widgets share the same DOM or a part of the DOM.
tag can help in abusing the functionality in some cases – This may also allow one Widget to access the important
say for example ”allow-top-navigation” parameter.
tags and variables of another Widget. In these cases, an
attacker can force a malicious widget on the DOM and
AV 8 - Abusing new features like drag- monitor other widgets.

and-drop

HTML 5 has some interesting innovative methods, events For example, consider a Widget which takes the username
and tags to make the browser application very rich in and password credentials. Here is a simple way in which

look and feel. This includes functionalities like drag and another Widget can set a trap on it.
22 HITB Magazine I JUNE 2011

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<script>
var w = new Worker('worker.js');
w.onmessage = function (event) {
document.getElementById('myresults').
textContent = event.data;
};
</script>

AV 10 - Threats to widgets and
mashups

Conclusion

The scenario of the web and the upcoming technology
stacks bears strong resemblance to the thief police
scenario. As the web world progresses, the demands of
users are matched by stronger and richer functionalities
growing by the day. The flipside of this coin is that
as such enhancements come about, loopholes and
vulnerabilities increase with the extended attack
surface. HTML 5, DOM L3 and XHR L2 are a combination
of this same kind. With the enormous enhancement
in the look and feel of the web applications that they
have brought, the attackers are also not likely to remain
Hence, a malicious widget is listening to the mouse event inactive. Thus along with bearing the advantages of

and as soon as the credentials are entered it can force these technologies it is of prime importance that we
GetU and GetP function calls to be made. These functions tread carefully and become aware to the new threat
can go ahead and steal the content and send it across the model and work on countermeasures. This can be
network to a place where the attacker may be listening. the only way to bear the advantages and yet not be
Evidently, It is important to analyze the DOM architecture bogged down by the attacks i.e. without loss of privacy
and security.
and usage when it comes to Widget platforms.

For example here is a simple worker.js script which we are
running in the background. It can use postMessage to
report back as well.

Iframe has been another potential place for abuse
within the browser stack all these years. It is a feature
to host cross domain content within the current page. It
allows cross domain calls and can be abused by forcing
Clickjacking.
This can be leveraged by spinet and botnet as well. They
usually load their script through the iFrame or script tag
New specifications have come up with a mechanism to but here is a different way to load the code. They can
provide a sandbox across the browser’s iframe. Some of load it using webworker and stay on the page in a hidden
these browsers have implemented these as well but those fashion. This makes their detection difficult for monitoring
instances can also be abused in a scenario as under:
tools as well.