A Look Into Emerging Security Issues Within Cryptocurrency Ecosystems
- 1. A Look Into Emerging Security Issues Within Cryptocurrency Ecosystems Beau Bullock Mike Felch
- 2. Overview • Brief background on what cryptocurrencies are • Various elements of the cryptocurrency ecosystem • A history of some major hacks • Some general vulnerabilities • Some blockchain-specific vulnerabilities
- 3. About Us • Mike Felch - @ustayready • Pentest / Red team at BHIS • Involved w/ OWASP Orlando and BSides Orlando • Beau Bullock - @dafthack • Pentest / Red team at BHIS • Podcaster, blogger, and guitarist • Tradecraft Security Weekly hosts • CoinSec Podcast hosts
- 4. What Are Cryptocurrencies? • Digital currencies that typically utilize a blockchain to regulate the generation of the currency, and verify the transfer of funds, usually in a decentralized manner. • There are over 1500 coins/tokens listed on coinmarketcap.com • Some of these have unique blockchains • Others are tokens built on top of blockchains using smart contracts.
- 6. Ecosystem: Blockchain • A digitized, decentralized, public ledger of all transactions • A combination of: • Private key cryptography • Peer-To-Peer (P2P) Network • Protocol governing incentivization • Records cannot be retroactively altered • Every node has a copy of the blockchain
- 7. Ecosystem: Blockchain Image source: https://dzone.com/articles/adopting-blockchain-how-a-devops-approach-can-help
- 8. Ecosystem: Nodes & Miners • Full Nodes • Download every block and transaction and check them against the protocol’s consensus rules • Maintain the decentralized “backup” • Miners • Verify transactions into a block • Solve a Proof-of-Work problem • Add block to the blockchain • Get rewarded
- 9. Ecosystem: Wallets • Wallets hold your private keys • Anyone that has your private keys can control your wallet • If you lose your private keys your coins are gone • Web/Mobile Wallets • Third-party hosted wallet using a web- based application for a user interface • Might be convenient but you don’t control your private keys
- 10. Ecosystem: Wallets • Desktop Wallets • Wallets are local to your computer • Full nodes require the full blockchain to be downloaded • At risk of hackers compromising your system • Hardware Wallets • Private keys are encrypted on a hardware device usually protected by a PIN • The software for interacting with the device can be prone to MiTM attacks • Paper Wallets • Private keys are printed and never stored digitally • If destroyed coins are lost
- 11. Ecosystem: Exchanges • Websites that facilitate the ability to exchange fiat currency for cryptocurrency • $, €, £, ¥, etc. BTC, ETH, LTC, etc. • …or cryptocurrency for other cryptocurrency • BTC, ETH, LTC, etc. BTC, ETH, LTC, etc. • Extremely high targets for attackers
- 12. Ecosystem: Smart Contracts • Code that sits on the blockchain • Can be self-executing and self-enforcing • Exchange of currency, data, shares, etc • Polls/elections (commit-reveal) • Removes the third-party from deals • Anyone can see (and execute) unless secured • Can’t be reversed • Not for EVERYTHING!
- 13. Ecosystem: ICOs • Initial Coin Offering (ICO) • A fundraising mechanism in which projects sell their underlying tokens • Ethereum raised $19 million in 2014 • The DAO raised over $150 million in 2016 • Most of the ICO world is ridden with scams • Some Ponzi schemes, some have no working platform, some take the money then disappear • Participants are highly targeted by phishers
- 14. Ecosystem: ICOs
- 15. Ecosystem: Malware • Ransomware • Generally requests payment in Bitcoin to decrypt files held ransom • WannaCry – Estimated to have infected more than 200,000 systems • Mining Malware • Coinhive – A JavaScript-based miner embedded in websites • WannaMine – Similar to WannaCry – Uses EternalBlue to infect, then mines
- 16. Some Major Cryptocurrency Security Events
- 17. Some Major Events • Mt. Gox - Feb. 2014 - 850,000 bitcoins went “missing” ($450 million at the time) • The DAO Hack - June 2016 - 3.6 million Ethereum stolen ($50 million at the time) • Parity Hack - Nov 2017 - $155 million of Ethereum “locked” forever • Coincheck - 2 weeks ago - $533 million of NEM stolen from a hot wallet • …Oh and $1.5 million is stolen from ICO’s every month
- 19. General AppSec Vulns • Overstock.com Payment Vulnerability • They accept Bitcoin for payments but users could pay with Bitcoin Cash instead (which is valued way lower) • Buy a $78 item for $12 • Refunds were in Bitcoin • EtherDelta Cross-Site Scripting • XSS injected into custom contract • Tricked user into adding the malicious token • Stole private keys Image source: https://krebsonsecurity.com/2018/01/website-glitch-let-me-overstock-my-coinbase/
- 20. Weak or No Encryption • BitPay/Copay apps wrote new wallet’s private keys to disk prior to encryption • Jaxx wallet – 12 word backup phrase stored with hardcoded encryption key • Coinomi wallet – Sent data in plaintext to Electrum servers leaking addresses • Blockfolio app – Unauthenticated and unencrypted retrieval of crypto holdings
- 21. DNS Hijacking • DNS Hijacking – An attacker compromises a site’s DNS server and redirects user traffic to a malicious site • Blackwallet Hack • Hijacked DNS and injected code to drain accounts with more than 20 Lumens • $400,000 worth of Stellar Lumens stolen • EtherDelta Hack • $250,000 worth of Ether stolen Image Source: http://resources.infosecinstitute.com/attacks-over-dns
- 22. Insecure JSON-RPC • Electrum Wallet • For over 2 years the JSON-RPC interface could be communicated with via JavaScript • Simply having the wallet open and surfing the web could allow for private keys to be stolen • Even with a password it still allows for potential brute force attacks • Reported on Github Nov. 2017, then again by Tavis Ormandy in Jan 2018
- 24. A Majority Attack • Also known as the 51% attack • Potentially allows the attacker to “double-spend” their own coins • Can prevent some transactions from gaining confirmations • Can prevent some or all of other miners from mining any valid blocks
- 25. Implementation Vulns • Short Addresses • In Lisk, addresses are 64-bit numbers, such as: 3040783849904107057L • Derived deterministically from a passphrase • SEED = SHA-256(passphrase) ED25519 KEYPAIR = SHA-512(seed) & scalar multiplication ADDRESS = Last 8 bytes of SHA-256(public key) • Preimage can be derived in approximately 264 evaluations • No Address-Key Binding • In Lisk, addresses aren’t bound to a keypair until it has sent tokens to another address • Attacker can derive preimage and hijack the account Source: https://research.kudelskisecurity.com/2018/01/16/blockchains-how-to-steal-millions-in-264-operations/
- 27. EVM: Virtual Machine • Run-time environment for smart contracts • Minimal instruction set (256 bit words) • Arithmetic, bit, logical, comparisons • Stack machine (not a register machine) • Contracts have storage, memory and stack • Isolated sandbox from network/fs/procs • Reusable code using delegate calls • Contracts can be made to self-destruct • Language, compilers and bytecode *oh my*
- 28. Ethereum Smart Contracts Source: http://www.gjermundbjaanes.com/understanding-ethereum-smart-contracts/
- 29. Exploiting Smart Contracts • Re-entrancy (The DAO Hack) • PRNG Predictability (Blockchain problem) • Delegated Fallback Calls (Parity Hack #1) • Schizophrenic Functions (Parity Hack #2) • Integer Underflows (The DAO Hack) • Unpredictable State (GovernMental DoS) • … more!
- 31. Securing Smart Contracts • Truffle: Develop, test, audit and deploy • Solium: Do code reviews • Mythril: Vulnerability scan contracts • OpenZeppelin: Use security libraries • Manticore: Fuzz, Crash and Taint analysis • Ethernaut: Hack contracts CTF style • Ropsten: Deploy to Ethereum test networks -Pentest all the things-
- 32. Conclusion • Don’t let the negative stigma around “blockchain” stifle your involvement • “Blockchain” has become a buzzword but some extremely innovative technologies have already, and will continue to be developed • Many companies are looking to integrate blockchain blindly • Vulnerabilities are surfacing in all aspects of the ecosystem including the wallets, exchanges, smart contracts, even blockchains themselves • New attack surfaces are forming • There’s much more research to be done around securing the cryptocurrency ecosystem
- 33. Resources • NIST – Guidance on Blockchain - https://csrc.nist.gov/CSRC/media/Publications/nistir/8202/draft/documents/nisti r8202-draft.pdf • DEF CON 25 – Hacking Smart Contracts by Konstantinos Karagiannis - https://www.youtube.com/watch?v=WIEessi3ntk • OpenZeppelin – https://openzeppelin.org/ • Ethernaut - https://ethernaut.zeppelin.solutions/ • Trail of Bits Blog - https://blog.trailofbits.com/ • Solidity - http://solidity.readthedocs.io/en/develop/ • Whitepaper on attacks https://eprint.iacr.org/2016/1007.pdf
- 34. Questions? • Black Hills Information Security • http://www.blackhillsinfosec.com/ • Beau - @dafthack • Mike - @ustayready • CoinSec Podcast - @coinsecpodcast • https://www.coinsecpodcast.com