Help! iPhone data usage out of control?

I think there's something very wrong with my iPhone. In the past few days (9/7 to 9/10, as listed on the AT&T web site), I have apparently used 3522.59 MB of data, with 1187147KB being used on the 8th at 12:20 AM, and 2373726KB used on the 10th at 11:57 PM. Not sure what I was doing on the 8th, but I was DEFINITELY sleeping at the time on the 10th. Besides, I've have my iPhone for almost a year, I know what I can and can't do on it, and all I did was email, Talkatone, and a little Facebook this entire week. Nothing beyond my regular usage.

I have an iPhone 4 on iOS 4.2, and it is jailbroken. I haven't downloaded any new apps in the past month (App Store, Cydia, or otherwise), but I did update some App Store ones somewhat recently (over wifi, and not in the past week, so that wouldn't account for this ridiculous data usage). I have however run some App Store apps that I haven't run before.

I honestly think I might have some sort of virus -- looking at my phone, I apparently installed SSH and completely forgot about it (I vaguely remember doing so now), meaning I never changed the default password. Or maybe one of those apps that I installed and never ran before might be doing something, but they were from the App Store.

Anyone, help? I can wipe my phone as soon as I get home, but would it stop this if it is a virus? How deep does the reset through iTunes go? And should I do this -- in case this actually is a virus, is there a way to make an image of my phone in case someone wants to look at it?

 

Yeah, I got that message. I'm using overage data now. P.S. My billing cycle started on the 7th.

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I can accept that, but I have NOT done anything that would use 2 GB of data in one day and 1 GB a different day. Email, Talkatone, and a little Facebook is seriously all I did. I don't stream music. I don't stream videos. I didn't even update my apps. I noticed the weird amount of data usage on Friday morning, and I tried to use my phone as little as possible (only work-related things like email and my calendar that I had to use) to make sure nothing weird was going on. My average data usage per month is about 300 MB. I also live alone, nobody was playing with my phone either.

I'm not one to call virus/malware/etc unless something really, REALLY screwy is going on.

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As a side note, how do I view the iPhone side of the data usage? I've been looking at AT&T's web site and the myAT&T app. The internet says go to Settings > General > Usage, but Usage is not on that menu at all. Is it different in iOS 4, or is this yet ANOTHER stupid thing going on with my phone? *headdesk*

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Also feel I should clarify that I only use Talkatone to receive/send text messages, not for calling. I'm not sure if it calls using VoIP or regular calls, but in any case, I haven't and never have used it for calls.

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Aaaaaaand another edit. One of my friends pointed out a botnet would be more likely. I agree with that. But if it IS a botnet, will changing the SSH password stop the data usage, or will the attempts to SSH into it also cause data to be used?