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arccosine.com has taken control of firefox


I use firefox and internet explorer. Both have been taken control by arccosine.com

Chosen solution

Your Anti-Virus Software may be blocking this , or further your 'hosts' may have been hijacked, as this should be viewed with a dose of skepticism.

Read this answer in context 5

Additional System Details

This happened

Every time Firefox opened

This started when...


Installed Plug-ins

  • The Hulu Desktop Plugin allows Hulu.com to integrate with the Hulu Desktop application.
  • Shockwave Flash 10.0 r45
  • Adobe Shockwave for Director Netscape plug-in, version 11.5
  • Next Generation Java Plug-in 1.6.0_26 for Mozilla browsers
  • NPRuntime Script Plug-in Library for Java(TM) Deploy
  • 4.0.60531.0
  • Motive Plugin for Mozilla Browsers
  • Adobe PDF Plug-In For Firefox and Netscape "9.4.5"


  • User Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:5.0.1) Gecko/20100101 Firefox/5.0.1

More Information

I ininstalled firefox and reinstalled.
Arccosine.com is not in the registry or as a file on disk.
They put their name on internet explorer screen.

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3193 solutions 24379 answers

Please explain what you mean by "control".

That website is used for searches, instead of using Google?
If so, which of the three sections of Firefox is that search engine being used?
Or all three sections?

  • Location Bar - where you type web addresses
  • Search Bar - to the right of the Location Bar
  • Search Container on the default Firefox 4+ homepage - about:home

Question owner

Changed the look of the browsers, including tool bars and the task bar. No task bar in firefox

palimadra 0 solutions 1 answers

I deleted the home icon from the navigation bar and changed my default search engine from arccosine. It seems arccosine is part of the search engines that are there as choices in the default searchbar. Why arccosine was chosen is anyone's guess but Firefox should have informed the users about this.

waverley1786 0 solutions 1 answers

Please explain how you changed the default search engine. I cannot find any way of doing it despite spending too much time in the help section.

Is the ARCCOSINE software safe to use for searches?

shrimants 0 solutions 6 answers

I cant vouch for the validity of Arccosine.com but from what I can tell it is just some random website that tries to imitate google.com's homepage. It hijacked my entire browser including the Homepage, search engine, and keyword.URL entry. I dont know to what extent this damage is, but I got rid of most of it by immediately going into my firefox sync settings and replacing all current data with server data.

I got this by searching for a way to download books from Google Books. Likely culprits are Google Book Downloader or GooReader. I think Gooreader is the most likely suspect because after installation there was no option anywhere to uninstall it. By chance I attempted reinstalling it and that allowed me to uninstall. Furthermore, the GooReader software claims to be free but every feature is locked down unless you buy it.

lioz 0 solutions 1 answers

Helpful Reply

i guess the problem kenb posted here is about the change of default search engine, i changed back to google, and here is how it could be done 1. open a new address bar and type in about:config 2. type in keyword.URL 3. change the search engine url to http://www.google.com/search?ie=UTF-8&oe=UTF-8&sourceid=navclient&gfns=1&q= done

Hotseflotse 0 solutions 1 answers

The culprit is Google Books Downloader. I just installed it and started having the arccosine problem immediately after that. I then scanned my pc with Antimalware but nothing came up, so it looks like i have to change my browsersettings back manually. Also Chrome seems to be unaffected, just Firefox an IE.

drtimofey 0 solutions 1 answers

Helpful Reply

  • type in about:config and search for: arccosine.com
  • replace all instances of arccosine.com with your preferred domain, i.e. browser.startup.homepage = http://google.com, keyword.URL = http://www.google.com/search?q=
  • change the default search engine, by clicking on a field icon, on the right side of the toolbar, and selecting another search engine (see attached image). You can remove arccosine.com completely by clicking on the field icon, Manage Search Engines and removing it from the list.
jeanfgr 0 solutions 1 answers

type about:config change keyword.URL=http://www.google.co.ve/search?q works with me!!! regards!!!

itsa.brandon 0 solutions 2 answers

It is not just googlebooks. I had this happen as well, and I have not downloaded that application. I downloaded an application. I noticed that my home pages and stuff changed too. So I extracted the exe file that I installed onto my computer. Inside the "CODE" file I could see it searching for a plugin, and making arccosine.com the home page and the primary search.

If you go out and do a "whois" on this site...it is getting an increasing volume of traffic here lately (wonder why).

These settings are coded inside a program that you installed intentionally or unintentionally. There does not appear to be any "harmful" issues with it. Basically any of us with this issue did give it permission when we ran the installer...My install file could have come form a better source honestly, I do not know if that is the case for everyone else.

itsa.brandon 0 solutions 2 answers

On a side note...if you are running 64-Bit windows you may find the location of the file here: "C:\Program Files (x86)\Mozilla Firefox\searchplugins" And probably "C:\Program Files\Mozilla Firefox\searchplugins" For 32-bit. Look for "arccosine.xml"

ravenheist 0 solutions 1 answers

why can't I open the site? arccosine.com

TerrificInTahoma 1 solutions 7 answers

Found the culprit. It was GoogleBooksReader that was downloaded from the net. the website 'arccosine.com' while looking nice, did not have a great User Interface, espescialyl with a vanilla(Generic) contact us page. Did a 'Whois' on arccosine.com, and it is hosted in the Russian Federation. Nice place to visit. Awfully cold in Moscow in winter. so I have disabled all references to arccosine.com. Check in the 'about:config' entries for 'keyword.URL'. Reset back to Default. 'Non-GoogleBooksReader' set it to 'arccosine.com,q=' without asking me.

Modified by TerrificInTahoma

TerrificInTahoma 1 solutions 7 answers

Chosen Solution

Your Anti-Virus Software may be blocking this , or further your 'hosts' may have been hijacked, as this should be viewed with a dose of skepticism.

TerrificInTahoma 1 solutions 7 answers

The Domain arccosine.com is hosted in [as of 2012-02-01] the Russian Federation, at IP It may be good, it may be bad. It is up to YOUR decision whether to use this search tool.

canuk2006 0 solutions 1 answers

The Arccosine was hidden inside the Google Reader add on that I downloaded from Mozilla. I did not check the exe file thinking it was safe but it highjacked Firefox and was redidirecting to fake Firefox site and would not let me use url locator for sites. It was some Russian highjacker, and when I reran the Google Reader exe I saw A checkmark box with a hook in it to install Arccosine . com as well. I did and uninstall of Google Reader and components, then I deleted all other files associated in folders that were not deleted. How could that highjacker have been inserted in a Goole File? My trust of Google and Mozilla products have diminished. My brand new computer already infected. *****See below:

Update: Thanks to Slartibartfarst who pointed out that the codelex.com was responsible for distributing Google Reader , it made me remember that Microsoft sends clients there via a link for desktop apps when looking for other apps on their site. Sorry Mozilla, I will report this to Microsoft. The strange part is that it did not affect my IE or Google browser, only the Firefox one which is my preferred one. What an Oops. This is from the Microsoft Downloads page -Gadgets:

"•Want to share a gadget that you’ve already created? CodePlex is a great option for hosting your gadgets." and the word CodePlex is a direct link from their page. The program is from Google so they say.


"Google has announced the launch of its new service; Google Books. Currently, you can purchase books (U.S. only) or download more than 3 million free books from anywhere in the world using this service. "

If you do a custom install on the exe file to install Google Book Downloader you will see Arccosine with an install check mark next to it.

I hope this helps.

Modified by canuk2006

Slartibartfarst 0 solutions 1 answers

Just a quick warning about this. (Jump to "Fix" at end of this post if you are in a hurry) I'm using Firefox 12.0 ß, but this problem may also occur with IE (according to a the Mozilla Support thread below).

Out of interest, I downloaded and installed Google Books Downloader, having seen a reference to it in a blog post (Codeplex daily summary - http://www.codeplex.com/) in my feed aggregator. The download site is/was: https://googlebookdownloa...x.com/releases/view/84266

The proggie did what it claimed to do - copied previews of books to .PDF - which unfortunately wasn't of much use as you are still frustrated by Google's removing pages from all previews.

Then I noticed that my home page and also my default Google search page had been hijacked by a search page which was imitating Google, with a pretty seascape background (see copy in spoiler): The ruddy thing wouldn't go away.

So, I de-installed Google Books Downloader and googled the problem, coming up with a useful Mozilla Support thread at https://support.mozilla.org/en-US/questions/850780

The hijack is persistent and comes from the website 'arccosine.com' and wants you to "sign up" for something. I did a 'Whois' on arccosine.com, and it is hosted in the Russian Federation. (That figures.)

Fix: I deleted all references to "arccosine" (i.e., 2x "C"s) and "arcosine" in history, just in case. I checked in the 'about:config' entry for 'keyword.URL' and reset that back to "Default" - it had been set to 'arccosine.com,q=' by the hijack proggie Google Books Downloader (in the discussion thread someone writes that if you examine the proggie's code, you can see where it does that).

Hope this helps someone to avoid/fix the thing.

TerrificInTahoma 1 solutions 7 answers

GoogleDownloader IS Not a Google.com application. It is not signed by google, it is Not verified by google. In the Source code website, Source code for developers an author, "Tubule" has the documentation, but, no source code for peer review.

There are warnings that the executable includes an optional(?) Link to add Arccosine as a search tool.

A windows install of a program is never 'safe', since it is not peer- reviewed, when it is in executable only format , and users should be forewarned.

fireman2 0 solutions 1 answers

guys i have found solution : type on address bar about:config and search in for " arccosine" must be in a key of name " Key Url " or similar , and this point modify the key with "https://www.google.it/search?q" if want search anything with google or any other search engine ( remember always "search?q after address of your preferite search engine)