Such as?

I know there are may ways one could gain access to attempt a brute force attack, especially since I had not enabled 2 factor authentication. I've ruled out access to my wallet backup as well as spyware on my phone.  There are only so many ways one can gain access to initiate a transaction, and some point to blockchain's site and phone app. I have shared everything I have dug up with them.

But the bottom line is that my blockchain wallet has been uses on and off for almost a year, no problems - and no use for the last several months. But just hours after installing their Android app, this happens.

Since I have a new account and can only post here, here goes.

I have wallet on blockchain.info.

Last night I switched to an Android phone, and installed the Blockchain.info client.  I have not used any cell phone bitcoin clients in the past.  

This morning, my phone beeped with a notification for a transaction of -0.0005 bitcoins.  I hadn't authorized any payments, and thought this was odd.  Soon the transaction was confirmed - my account was drained!  The transaction is here:

https://blockchain.info/tx/ad688e21be30e00e01a9417a9ad0201f7e54e496f4d85896991064895ab21971

I find it beyond coincidental that this transaction occurred just hours after installing their client on my phone - it is my only related activity to this wallet in months.   Even if it was, it may call into question the security of their system. Sure there are other possibilities (maybe someone hacked my home network) but this sure seems the most likely.

I realize that tracing this down is next to impossible, but I am posting this as a warning to other blockchain.info users. Their system or components of it may be compromised.

And no, I did not have 2 factor authentication enabled.  Lesson learned.  It would have stopped this from happening.