# Tor Browser - User Agent Spoofing Changes (Still secure?)

**URL:** https://discuss.privacyguides.net/t/tor-browser-user-agent-spoofing-changes-still-secure/22110
**Category:** General
**Tags:** software
**Created:** 2024-11-05T05:55:57Z
**Posts:** 4

## Post 1 by @lnmouseQ9 — 2024-11-05T05:55:57Z

> Historically, Tor Browser has spoofed the browser user agent found in HTTP headers, while not spoofing the user agent returned by the `Navigator.userAgent` property in JavaScript. The logic behind the HTTP header spoofing was to prevent passive tracking of users’ operating system by websites […] So, _why_ are we considering making this change? Basically, asymetrically spoofing the user agent causes website breakage seemingly due to bot-detection scripts. And (in our analysis) it also provides only a negligible amount of benefit to the user in terms of additional linkability (i.e. cross-site tracking, fingerprinting) protections, and only then when JavaScript is disabled. Tor Browser’s default HTTPS-Only mode (and much of the web having moved to HTTPS) has also significantly reduced the utility of passively sniffing HTTP traffic for user agents as well.

[Source](https://blog.torproject.org/new-alpha-release-tor-browser-140a4/)

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## Post 2 by @dumpster — 2024-11-05T06:55:32Z

strange that user agent spoofing triggers bot detection scripts. how do they know when we’re spoofing?

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## Post 3 by @ruihildt — 2024-11-05T07:24:40Z

They know, because user agent is not the only way to determine the OS with JavaScript.

So if you look at the user agent and JavaScript, and see a mismatch OS, you can infer the user is lying and use those parameters to block them.

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## Post 4 by @anonfox — 2024-11-05T11:21:01Z

It’s probably not too different unless you block javascript, anti fingerprinting wise.

Tor devs previously said they didn’t do it because of usability concerns on macOS. [Browser Fingerprinting: An Introduction and the Challenges Ahead | The Tor Project](https://blog.torproject.org/browser-fingerprinting-introduction-and-challenges-ahead/#comment-283726)

I think that the total number of tor network users are 2 million. This includes people using tor browser and orbot, onion browser, etc. The number of Tor users on each desktop platform is probably in the few hundreds of thousands or less. I hope this is enough of a crowd