Problem with a Wallet—Outgoing Transaction Appeared

Question

Yesterday I thought it would be good if I send my Iotas to a wallet. I had previously generated seed which worked fine and I did some transfers from and to exchange.

Yesterday I did a transfer from Bitfinex to my wallet, but in the history there were only shown a pending transactions for 0 Iota, I tried reattaching them and rebroadcasting them but it didn't help so I changed to a different node and this is what i got.

So it looks like my transfer was received successfully but after some time it was send somewhere? Was my wallet hacked or I did something wrong? That 17 minute difference is probably the time after I tried rebroadcasting.

I generated my seed using bash:

cat /dev/urandom |LC_ALL=C tr -dc 'A-Z9' | fold -w 81 | head -n 1

Here are transaction and bundle details TXID from exchange to wallet FFKNEBK9UIATPVWDNFTCTY9DKXQNNHVKETTYK9QVANGMFJQKUSQJEDEMSYESLBMXAX9TKMVYQGDOZ9999

Bundle that has -699.5 Mi BJTDKE9JWIBQQELUFBCAKJVPVUMPAFQSRRZPY9KTGBNIFNWNWRXXBFSVYOLPBIJJZYJWLESUHHEPA9999

Bundle that has 699.5 Mi HONDFGSENCAIRDSAJLWFYYLIZHOPYGLXWOVFNDALEHHBHEWTCDWWNORPNJMRQCMELSPVQSVJEWRN99999

Answer 1

You did not post your address, which is VVF9HAQEFNSVTWZBWTDQJSERIXMZHMOYVCBZJAPMDMEPJRHVFYSIFJCYKT9TNVHYWRRREANC9FCMTDFCZ.

My questions: When did you generate that seed? Was it new or did you already do some experiments with it (like transferring 1.8 GIOTA from it) in October?

Regardless whether it was you or not, that address has already been used (and spent from) in October, and possibly (as thetangle.org does not contain the whole tangle history) even before. So at least half of your private key is already leaked.

(this is speculation: We are still waiting for a blog post what exactly makes bundle hashes with a M in the first half more insecure - as the new wallet avoids signing bundles with this hash. I assume that it causes everything in your private key starting from that point to be leaked, i.e. is an attack against how the key material is generated deterministically from the seed. And your first spending transaction's bundle hash has the M at third place)

Regardless that speculation: When you have an old used seed where you removed all funds from it earlier, either generate a new one or make sure not to use the first already used addresses again.