Tor Browser 4.5 introduces security slider and improvements

Martin Brinkmann
Apr 28, 2015

The Tor Browser Team has released Tor version 4.5 for all supported operating systems. The update is considered significant which is why automatic updates have been delayed for a week.

Tor users running an older version of the browser can download the most recent build from the official project page.

Here is a short introduction to Tor in case you have never come into contact with it. Tor Browser is a hardened customized version of Firefox that uses the Tor network to protect your privacy on the Internet.

The browser ships with Tor integrated (and security add-ons such as NoScript and HTTPS Everywhere) which means that you only need to download and run it to stay anonymous in the Internet and improve security and privacy in the process.

tor browser 4.5

A new feature of Tor Browser 4.5 is the security slider which you access with a click on the Tor icon and the selection of privacy and security settings from the menu that opens up.

There you find a slider to adjust the general security level of the browser. The default level is set to low which ensures compatibility with most sites and technology.

tor security slider

If you switch it to medium-low instead, changes are made to the browser. Here is a list of what each level changes:

  • High - JavaScript is disabled on all sites by default, some types of images are disabled.
  • Medium-High - All JavaScript performance optimizations are disabled, some font rendering features are disabled, JavaScript is disabled on all non-HTTPS sites by default.
  • Medium-Low - HTML5 video and audio are click-to-play, some JavaScript performance optimizations are disabled, remote JAR files are blocked and some methods to display math equations are disabled.
  • Low (default) - All browser features are enabled.

Compatibility drops and security rises with each security level. The settings display privacy related options as well which are all enabled by default.

Browsing history and data is not recorded which means Tor Browser runs private browsing mode permanently unless the feature is disabled. Furthermore, plugins are disabled and third-party cookies restricted.

The Tor menu itself has been improved as well. It displays information about the active Tor circuit and an option to change the circuit with a single click.

The circuit refers to the servers your traffic is routed through on its way to the website or application you open in the Tor Browser.

tor circuit

Overall circuit handling was improved in this release. Was it previously sometimes the case that circuit information changed suddenly, and with it information about your location and language among other things, it is now the case that the same circuit will be used while a site is active in the browser.

Additional security and privacy improvements are introduced in Tor Browser 4.5. Here is a short list:

  1. SharedWorker API has been disabled to prevent cross-site and third-party communication.
  2. Device sensor and video statistics APIs have been disabled.
  3. Rewrite of obfs2, obfs3 and ScrambleSuit transports and introduction of obfs4 transport which comes with additional DPI and probing resistance features.
  4. Windows packages are signed by DigiCert.
  5. Automatic updates are signed with an offline signing key now.
  6. Default search provider changed to Disconnect.

Now You: Are you using the Tor browser? What's your take on the update and the browser in general?

Tor Browser 4.5 introduces security slider and improvements
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Tor Browser 4.5 introduces security slider and improvements
The Tor Browser Team has released a new version of Tor Browser which introduces a security slider and other improvements.

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  1. ilev said on August 4, 2012 at 7:53 pm

    Doesn’t Windows 8 know that www. or http:// are passe ?

    1. Martin Brinkmann said on August 4, 2012 at 7:57 pm

      Well it is a bit difficulty to distinguish between domains and files for instance.

    2. Leonidas Burton said on September 4, 2023 at 4:51 am

      I know a service made by google that is similar to Google bookmarks.

  2. VioletMoon said on August 16, 2023 at 5:26 pm

    @Ashwin–Thankful you delighted my comment; who knows how many “gamers” would have disagreed!

  3. Karl said on August 17, 2023 at 10:36 pm


    The comments section under this very article (3 comments) is identical to the comments section found under the following article:

    Not sure what the issue is, but have seen this issue under some other articles recently but did not report it back then.

  4. Anonymous said on August 25, 2023 at 11:44 am

    Omg a badge!!!
    Some tangible reward lmao.

    It sucks that redditors are going to love the fuck out of it too.

  5. Scroogled said on August 25, 2023 at 10:57 pm

    With the cloud, there is no such thing as unlimited storage or privacy. Stop relying on these tech scums. Purchase your own hardware and develop your own solutions.

    1. lollmaoeven said on August 27, 2023 at 6:24 am

      This is a certified reddit cringe moment. Hilarious how the article’s author tries to dress it up like it’s anything more than a png for doing the reddit corporation’s moderation work for free (or for bribes from companies and political groups)

  6. El Duderino said on August 25, 2023 at 11:14 pm

    Almost al unlmited services have a real limit.

    And this comment is written on the dropbox article from August 25, 2023.

  7. John G. said on August 26, 2023 at 1:29 am

    First comment > @ilev said on August 4, 2012 at 7:53 pm

    For the God’s sake, fix the comments soon please! :[

  8. Kalmly said on August 26, 2023 at 4:42 pm

    Yes. Please. Fix the comments.

  9. Kim Schmidt said on September 3, 2023 at 3:42 pm

    With Google Chrome, it’s only been 1,500 for some time now.

    Anyone who wants to force me in such a way into buying something that I can get elsewhere for free will certainly never see a single dime from my side. I don’t even know how stupid their marketing department is to impose these limits on users instead of offering a valuable product to the paying faction. But they don’t. Even if you pay, you get something that is also available for free elsewhere.

    The algorithm has also become less and less savvy in terms of e.g. English/German translations. It used to be that the bot could sort of sense what you were trying to say and put it into different colloquialisms, which was even fun because it was like, “I know what you’re trying to say here, how about…” Now it’s in parts too stupid to translate the simplest sentences correctly, and the suggestions it makes are at times as moronic as those made by Google Translations.

    If this is a deep-learning AI that learns from users’ translations and the phrases they choose most often – which, by the way, is a valuable, moneys worthwhile contribution of every free user to this project: They invest their time and texts, thereby providing the necessary data for the AI to do the thing as nicely as they brag about it in the first place – alas, the more unprofessional users discovered the translator, the worse the language of this deep-learning bot has become, the greater the aggregate of linguistically illiterate users has become, and the worse the language of this deep-learning bot has become, as it now learns the drivel of every Tom, Dick and Harry out there, which is why I now get their Mickey Mouse language as suggestions: the inane language of people who can barely spell the alphabet, it seems.

    And as a thank you for our time and effort in helping them and their AI learn, they’ve lowered the limit from what was once 5,000 to now 1,500…? A big “fuck off” from here for that! Not a brass farthing from me for this attitude and behaviour, not in a hundred years.

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