Notes from Zaif Attack

The following is primarily a translation of this blog post.

On September 20, 2018, Tech Bureau sent out a notice that they suspended deposits and withdrawals for three currencies (BTC, MONA, BCH) on the Zaif cryptocurrency exchange due to unauthorized access to its systems. This post is an aggregation of the details of that event.

Press Releases

Tech Bureau

Incident Timeline

TimeEvent
2018.09.14 between 17:00-19:00Approximately 6.7 billion JPY worth of assets were withdrawn without authorization.
2018.09.17Tech Bureau detected an anomaly within the environment.
- eveningTech Bureau suspended withdrawals/deposits for 3 currencies on Zaif.
2018.09.18Tech Bureau identified they had suffered a hacking incident.
- same dayTech Bureau reported the incident to the local finance bureau and started filing papers with the authorities.
- same dayThe official Zaif Twitter account tweeted that customer financial assets are safe.
- same dayIn accordance with the Payment Services Act, the FSA issued a Request for Report to Tech Bureau.
Post-identificationTech Bureau enters into a contract with Fisco for financial support.
Post-identificationTech Bureau enters into a contract with CAICA for assistance in improving security.
2018.09.20 ~2amTech Bureau issues a press release declaring that deposits/withdrawals were suspended due to a hacking operation.
- same dayThe Japan Cryptocurrency Business Association appealed for a member to perform an emergency inspection.
- same dayThe FSA sent an on-site inspection crew to Tech Bureau.
2018.09.21ETA for the FSA to issue a report on its investigation about the status of customer assets to the cryptocurrency exchange's traders.

Damage

  • Approximately 6.7 billion JPY worth of 3 different currencies were withdrawn externally without authorization.
  • Withdrawals and deposits for the 3 affected currencies have been suspended since the evening of 17 September.

Itemization of damages

Tech Bureau's own assets~2.2 billion JPY
Customer assets~4.5 billion JPY
  • Tech Bureau has shown that they can cover the 4.5b loss of customer assets through financial assistance from the FDAG subsidiary.

Information around the Zaif hack itself

  • Funds were withdrawn from the server managing the Zaif hot wallet.
  • Tech Bureau is still investigating the exact method of intrusion, but it doesn't look like they'll publicly announce it as a protective measure.

Details on the unauthorized transactions

Total (estimated) damages on the 3 currencies

CurrencyAmount transferredJPY conversionUSD conversion
Bitcoin5966 BTC4.295 billion JPY38.207 million USD
MonacoinUnder investigation, but sources estimate 6,236,810 MONA650 million JPY5.782 million USD
Bitcoin CashUnder investigation, but sources estimate 42,327 BCH2.019 billion JPY17.954 million USD

Assumed recipient addresses of the hack

CurrencyAddressTime of transaction
Bitcoin1FmwHh6pgkf4meCMoqo8fHH3GNRF571f9w2018.09.14, between 17:33:27 and 18:42:30
Bitcoin Cashqrn0jwaq3at5hhxsne8gmg5uemudl57r05pdzu2nyd2018.09.14, between 17:33:15 and 17:51:24
MonacoinMBEYH8JuAHynTA7unLjon7p7im2U9JbitV2018.09.14, between 17:39:01 and 18:54:10

work in progress



Disclaimer: I make no guarantees of the accuracy of the above article.
Please see the official press releases and/or PR department at Zaif. I am also not affiliated with Zaif or any of the companies mentioned in this article.