Redacted Statement
Apologies are needed in my haste to report i had mistaken some key details,
The active side in this is Coinbase
The passive sides are Huobi Bittrex Polo
Im told by Twitter that Coinbase is where the transactions came from and are going to Bittrex Huobi Poloniex.
Here is what Coinbase said on the matter via : collapzcursed
Sorry again if my incorrect information inconvenience anyone.
I have struck out the incorrect information and removed some screens/images from this post.
There has been a recent replay attack occurring with Poloniex and Coinbase,
It is advised to move coins from Poloniex and Coinbase as soon as possible.
A replay attack (also known as playback attack) is a form of network attack in which a valid data transmission is maliciously or fraudulently repeated or delayed. This is carried out either by the originator or by an adversary who intercepts the data and re-transmits it, possibly as part of a masquerade attack by IP packet substitution.
Another way of describing such an attack is: "an attack on a security protocol using replay of messages from a different context into the intended (or original and expected) context, thereby fooling the honest participant(s) into thinking they have successfully completed the protocol run.
What is a Bitcoin Replay Attack: The Merkle
Tx ids Showing some transactions relating to.
A TXID (Transaction ID) is basically an identification number for a bitcoin transaction.
4.44110abfd91e9276bbb43ca7fe5edc4c1ab494caeeee17e3585737a915359a27
5.c8c7eef7ad324a5938d3b2d2f1f16dfc8ecfdbed2379808bc2e6f779cbdf92aa
6.d7f879377e71e6fb7e0565ab8f303ac6417d005d3142ed279fa5649efa901132
7.77a9d5b61bc4e5b965b4ce99ee43e11f5a1c428ac6786a6117d4de0f725d984b
What this means for funds on poloniex
Someone managed to use an exploit on Poloniex's ability with broadcasting of Bitcoin transactions to new wallets from Coinbase generating multiples of the same stealing funds.
The transactions originated from Coinbase wallets.
At this time is unknown how much was taken or how many users were effected.
It is advised to move funds to another wallet or exchange.
its always safest to use your own personal wallet and to keep your private keys safe and backed up.
If you are using an exchange to trade i would suggest:
I would also like to warn against depositing to Kraken at this time due to withdrawals being delayed and support is under heavy backlog.
Update
It seems both Coinbase and Poloniex could be comprised,
with funds coming out of multiple wallets Poloniex to a wallet owned by Hacker group The Shadow Brokers,
This is a hot wallet used by Poloniex for unspent transactions
12cgpFdJViXbwHbhrA3TuW1EGnL25Zqc3P
Also it seems Coinbase stopped responding to support emails.
Mention of coinbase stopping accepting emails on support
Discovery of Hacker wallet.
The offending users wallet 12cgpFdJViXbwHbhrA3TuW1EGnL25Zqc3P
This wallet belongs to the Shadow Broker Hacker Group
Is a Hot Wallet owned by Poloniex for unspent transactions.
There isn't any confirmation from either Coinbase or Poloniex on the matter at this time will update post as soon as more information is available.