I rarely see folk that know how to really reset a router. Also you have ISP's that deliver adverts so it may not be any hack at all.
My bet is the router was not reset. Just rebooted.
From past one week, i was facing redirection issues in all my devices (android, ubuntu, win7). I thought they all got virus, however when i used to surf net in my office there was no such redirection. So i thought that my ISP is the culprit.
I had raised the issue to them and they will be visiting me tomorrow to check the issue.
But just now, i found i am not able to login to my router at all. Err connection refused. Tried everything i could (reset router, reset ip, reset dns, dns flush) but still i am not able to.
Now after reading what an hacker can do after hacking a router, it all seems like I got hacked.
These are redirection links that are happening too frequent:
http://ad-type.google.com/sh.aspx?f=popup-u&h=c8d5ad7d804ba49015d1b83443fbc54d
http://www.tradeadexchange.com/a/display.php?k=55eef8460ae915906627.11476236&h=252bd4311a99466d6e788508710ae0f5da21cc56&ban=5906627&r=425636&iid=14417244852057429412101631718767393&exp=prpd&ci=%3D%3DgSKdwBBQQDV4kVbJ1UVsxBHMQAP0QFORVWSJkRSVUUVshDO4gDO0QFONkXDllVCZUFM1QF1VxGKdQDV4kVbJ1UVsxBHMQAP0QFORVWSJkRSVUUVshDO4gDO0QFONkXDllVCZUFM1QF0VxGKdQDV4kVbJ1UVsxBHMQAP0QFORVWSJkRSVUUVshDO4gDO0QFONkXDllVCZUFM1QFtVBT&pm=VM0WCZVUSNVF&pabt=%3DUhAFkhBn1GaHcUF&id=5906627
http://www.snapdeal.com/?utm_source=aff_prog&utm_campaign=afts&offer_id=17&aff_id=12865&source=68327
http://www.shine.com/registration/?vendorid=4245&src=Email&adn=Pointific&acc=Pointific&cmp=Registration&adg=369&kw=&mt=&purl=cmm&utm_source=Pointific&utm_medium=Email&utm_campaign=Acquisition
Some engg from Airtel(ISP) will be visiting tomorrow to check this. But I am just too curious to know how did someone breached into my wifi which has very short signals and cannot be connected by other people.
Is it possible that it can be hacked from anywhere and a person can block the admin panel to my router sitting too far from me.
So far no suspicious activity / transactions have happened but i fear that something can happen now. Will be resetting each and every passwords now.

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