Why is safari redirecting to Yahoo Guesthouse

Question

I have a iPhone 5. When I go to Safari to search something it automatically redirects my phone to Yahoo Guesthouse. I have never used Yahoo Guesthouse and have no clue what it is. How do I get my phone to stop doing this!
Thank you

Answer 1

Open Terminal and type
pico /etc/hosts
and press enter, if you see something like this your fine
Use the arrow keys to mouse down and if there is anything below what you see on the image above (below the last two "localhost" lines) you have been compromised. Delete those lines and Exit, it will ask to save which you will need to enter the admin password.
If that doesnt' work use
sudo pico /etc/hosts
and perform the same operation, if your in standard user, switch to admin user first as sudo won't work in standard user by default.
Once you've done that use Software Update, it fixes a fake certificate issue.
You should backup your user file folders (Music, Library, Documents etc) to a external drive (not TimeMachine) and hold Command R and boot into the Lion Recovery Partition and install Lion on top of your installed version then Software Update.
Reinstalling Lion without erasing the OS x partition just replaces Lion and Apple's bundled programs, not your third party programs or files (but you backup anyway just in case you have too)
If one of your third party programs is a trojan, you really should replace all with fresh copies.
Also use Firefox with NoScript, Ad Block Plus and Web of Trust (WOT) as these will help protect yur machine and you from being compromised.