BlockThreat - Week 32, 2020

Another serious 51% attack against ETC with $1.68M double spent, two vulnerable DeFi apps, and an exchange in Spain compromised. On the brighter side, I had a blast presenting during the Blockchain Security Village last weekend, links to both of the talks below! Finally, Zoom hearing for the Florida teen involved in the Twitter hack was zoombombed to play some explicit videos.

Hacks

• Second 51% attack against Ethereum Classic resulted in a massive 4236 block reorg and 238,306 ETC ($1.68M) double spent on Bitfinex and another crypto service. Just like in the previous attack, the malicious miner used Nicehash to rent mining capacity. Nicehash has responded that it is essentially powerless to prevent its services from being used for 51% attacks; however, miners have previously voluntarily reported these to asset issuers in the past.
• Opyn ETH Put contracts have been exploited to steal 371k USDC. Another 572k USDC were recovered after the developers were made aware of the exploit and got help from the community.
• On July 31st, 2020 2gether exchange has suffered a breach where 114 BTC, 276 ETH, and user data were stolen. No details about the hack were disclosed.

Vulnerabilities

• yVault was found to have a vulnerability which could have resulted in attackers completely draining pool’s assets. The vulnerability was quickly patched after responsibly disclosed by samczsun.

Events

• Blockchain Village at Defcon was an absolute blast with dozens of talks on various blockchain security topics such as smart contract, nodes, wallet security and insecurity. I had a great time presenting the keynote talk on The State of Blockchain Security and results of a research on Attacking and Defending Blockchain Nodes. Many other talk recordings are currently available on Blockchain Village’s Twitch channel and on Defcon’s media server. Kudos to Ajit and all of the speakers for organizing this event.

Research

• An interesting analysis of NetWalker BTC transactions from folks at CipherTrace. The Ransomware-as-a-Service, Netwalker, shows sophistication with the use of cold storage, dividing up profits between operators and affiliates, and SegWit to reduce transaction fees.
• Cryptocurrency Money Laundering Explained.

Stay informed, stay healthy, and head over to /r/blocksec subreddit for blockchain security news throughout the week.

-Peter