The Pentester’s View on Blockchain Projects Pertsev Alexey @_p4lex

Agenda DApp? How does it work? Examples of vulnerable contracts The Pentester’s View on Blockchain Projects Agenda DApp? How does it work? Examples of vulnerable contracts Client-side vulnerabilities Digital Security ICO case Common attack vectors at ICO address changing Latest security incidents overview

DApp and DAO Browser Ethereum HTTP Requests Gateway Smart Contact The Pentester’s View on Blockchain Projects DApp and DAO Browser Ethereum HTTP Requests Gateway Smart Contact address = “0xdeadbeef…” Transaction Transaction ABI = [{“name”: “crowdsale”…}] Geth Parity cpp-Ethereum web3 object Call results, events…

Smart Contract’s Vulns/Attacks/Features The Pentester’s View on Blockchain Projects Smart Contract’s Vulns/Attacks/Features Blockchain specifics: Front-running attack Timestamp dependency Generating randomness Unpredictable state Keeping secrets Solidity specifics: Evolution of money sending: Reentrancy Gasless send DOS (due to exception disorders) Self-destruction Inheritance EVM specifics: Integer overflow (no exceptions) ABI encoding/decoding (no args checks) Short Address Attack Type confusion Uninitialized storage pointer Logical (project specifics): Name it yourself :)

Logical vulnerabilities The Pentester’s View on Blockchain Projects Logical vulnerabilities Forgotten access modifiers Misspelled identifications (variables, functions) Huge variety of race conditions Subject area specifics etc…

Logical vulnerabilities – DSec ICO The Pentester’s View on Blockchain Projects Logical vulnerabilities – DSec ICO

Logical – commit-reveal The Pentester’s View on Blockchain Projects Logical – commit-reveal Commision fee is up to a user, never from smart contract.

Then attacker can withdraw ether from Coinbase and repeat! The Pentester’s View on Blockchain Projects Ethereum account balance manipulation (Coinbase) 1 ETH + 1 ETH Wallet1 1 ETH + 1 ETH Attacker Smart Contract Coinbase Wallet2 1 ETH + 1 ETH Wallet3 4 ETH (Ethereum view) 1 ETH (Coinbase view) Then attacker can withdraw ether from Coinbase and repeat! Broken Smart Contract + 1 ETH Coinbase $10k bounty 0 ETH (Ethereum and Coinbase* view)

Client-side vulnerabilities and vectors The Pentester’s View on Blockchain Projects Client-side vulnerabilities and vectors Leaving blockchain aside, can I hack ICO without blockchain knowledge? XSS Phishing Site defacement + clipboard manipulation Social Engineering etc… And other vectors: Weak passwords for Social Network accounts (twitter, slack, FB, etc.) Hacking related infrastructure and pivoting

Blockchain-stored XSS The Pentester’s View on Blockchain Projects Blockchain-stored XSS Protection: Don’t trust user data! Always cast, validate, sanitize and escape (order is meaning!)

Phishing kickico $50k Hack Tree steps to phishing: Mitigations: The Pentester’s View on Blockchain Projects Phishing Tree steps to phishing: Register a domain name similar to a victim’s one: kickico.com -> kickico.co Copy a victim’s website and replace ICO smart contact address Spam spam spam! kickico $50k Hack Mitigations: Be offensive! Monitor similar domains and inform users (URLCrazy) Metamask EtherAddressLookup blacklist Register phishing site at local DNS and resolve them to alert page (for team only)

Site defacement and Clipboard manipulation The Pentester’s View on Blockchain Projects Site defacement and Clipboard manipulation Easy to understand: Hack website -> full control information on it Change ICO address to your own CoinDash.io $7 Million Hack Or a more tricky one… Clipboard manipulation:

$500k HACK Weak passwords There is nothing new here, same old story. The Pentester’s View on Blockchain Projects Weak passwords There is nothing new here, same old story. $500k HACK Protection? You already know: 2FA Password managers OAuth etc.

Social Engineering + Phishing The Pentester’s View on Blockchain Projects Social Engineering + Phishing

Pivoting Numerous attack vectors! Attack surface: Interfaces (web) The Pentester’s View on Blockchain Projects Pivoting Attack surface: Interfaces (web) Social network and email accounts Third-party Lib/Apps/Chats/API Oracles (shapeshift and similar) Mail/VPN/WEB/Mobile/… server Totally ALL host you control (laptops too) Numerous attack vectors!

Recommendations Smart Contract security: Infrastructure: The Pentester’s View on Blockchain Projects Recommendations Smart Contract security: Best practices Code auditing Bug Bounty (almost free for you!) Infrastructure: Best practices Auditing / Security assessment / Penetration testing Close/hide all optional services

Let’s talk Pertsev Alexey @_p4lex a.pertsev@dsec.ru The Pentester’s View on Blockchain Projects Let’s talk Pertsev Alexey @_p4lex a.pertsev@dsec.ru