Simon Willison’s Weblog

Entries tagged quora, security, javascript

Filters: Type: entry × quora × security × javascript ×


Why would someone browse the web with JavaScript disabled?

Security conscious users (who understand the implications of XSS and CSRF attacks) sometimes disable JavaScript completely, or use a tool like the NoScript extension to disable it for all sites and only re-enable it on a small whitelist of sites that they trust.

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What are the JSON security concerns in web development?

Be very careful when implementing JSON-P for authenticated actions—evil third party sites could assemble URLs to your user’s private data and steal it. This attack has worked against Gmail in the past.

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Why do browsers allow cross-domain JavaScript to execute but not XMLHttpRequests?

It’s called the Same Origin Policy, and it’s principally about intranets. Imagine you have a URL http://intranet.corp/top-secret-...—and you then visit http://evil.example.com/ . If cross domain XHR was allowed the evil site could suck that secret document off your intranet without you realising.

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Why do some websites implement their logout link as a form post via JavaScript versus a plain old GET request?

Probably because if you implement logout as a GET action, I can force you to log out of a site by tricking you in to visiting a page with an <img src="http://yoursite.com/logout/" width="1" height="1"> element on it.

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Why are XSS attacks spreading like fire these days?

XSS attacks are common and easy, and crop up all the time. What’s new is that the number of people who are aware of the potential for XSS worms has increased hugely, so when an XSS does crop up in something popular there’s a much higher chance of someone turning it in to a worm (as happened with Twitter the other day).

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Why do some people disable JavaScript in their browser?

For security reasons.

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