Crypto wallets security: for developers

by Julia Mezher

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Crypto Wallets Security for developers Julia Potapenko

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Security Software Engineer Julia Potapenko @julepka We help companies to protect their sensitive and valuable data. OWASP Zhytomyr Leader. Contributor to OWASP security standards and guides. Women Who Code Kyiv Director

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OWASP Open Web Application Security Project A nonpro f it foundation that works to improve the security of software OWASP Top 10 OWASP ASVS OWASP WSTG OWASP MASVS/MSTG https://owasp.org/www-project-mobile-security-testing-guide/ https://owasp.org/www-project-application-security-veri f ication-standard/ https://owasp.org/www-project-web-security-testing-guide/ https://owasp.org/www-project-top-ten/

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Today we will talks about #cryptocurrency_wallets #sensitive_assets #authentication #local_storage #platform #cryptography #dependencies_management

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How does it work? Your account = your seed / private key Loosing seed / private key = loosing the account Wallet gives access to several accounts The main challenge is to secure seed / private keys

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Cryptocurrency wallet types Custodial third-party storage Non-custodial user-controled

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Cryptocurrency wallet types Custodial third-party storage Non-custodial user-controled Hot online Cold of f line

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https://www.wired.com/story/hack-binance-cryptocurrency-exchange/ Why should devs care?

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https://www.wired.com/story/hack-binance-cryptocurrency-exchange/ https://www.bbc.com/news/technology-59549606 Why should devs care?

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https://www.theverge.com/2022/1/24/22898712/crypto- hardware-wallet-hacking-lost-bitcoin-ethereum-nft https://www.wired.com/story/hack-binance-cryptocurrency-exchange/ https://www.bbc.com/news/technology-59549606 https://www.theverge.com/2021/11/4/22763015/cryptocurrency- fake-wallet-phishing-scam-google-ads-phantom-metamask Why should devs care?

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Cryptocurrency wallet types Custodial third-party storage Non-custodial user-controled Hot online Cold of f line

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Coinbase wallet example

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Similar to banking apps, cryptocurrency wallets operate user funds, meaning security baseline should be nearly the same.

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Similar to banking apps, cryptocurrency wallets operate user funds, meaning security baseline should be nearly the same. Threat vectors considerations • Authentication • Local storage • Platform trust • Cryptography • Communication • User education • Supply chain

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User Authentication LOCAL VS REMOTE If the app provides users access to a remote service, some form of authentication, such as username/password authentication, is performed at the remote endpoint. No sensitive data should be stored locally on the mobile device. Instead, data should be retrieved from a remote endpoint when needed and only be kept in memory. If sensitive data is still required to be stored locally, it should be encrypted using a key derived from hardware backed storage which requires authentication. – OWASP MASVS 4.1, 2.11, 2.12

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Password policy Password rotation when leaked Defences against brute-force attacks Step-up authentication Biometry veri f ication User Authentication

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Know your platform What kind of storage should be used to deliver the best security guarantees?

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Know your platform What kind of storage should be used to deliver the best security guarantees? Is it a f ile? Can you steal it? Can other apps access it? What about integrity? And Encryption?

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Know your platform What kind of storage should be used to deliver the best security guarantees? Is it a f ile? Can you steal it? Can other apps access it? What about integrity? And Encryption? It is a developer’s responsibility to know how the storage works on the platform you use.

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000003.log is a storage f ile of web-extension. You can copy it from one browser and paste into another. Know your platform

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Objection tool that allows to access Keychain of the device, no jailbreak required Know your platform

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Cryptography How to encrypt the data with a password?

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Cryptography How to encrypt the data with a password? You decided to pick AES. You need a key length of 256 bits but the password is shorter. You use a hash function SHA256.

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Cryptography How to encrypt the data with a password? You decided to pick AES. You need a key length of 256 bits but the password is shorter. You use a hash function SHA256. KDF (Key Derivation Function) Your pick PBKDF2. You need to specify number of rounds for it. Similar to some example in the Internet you pick 2 000.

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Cryptography Comes from mvayngrib/react-native-crypto library… that uses react-native-randombytes library… that uses Stanford Javascript Crypto Library (SJCL) for synchronous random values generation. React Native mobile app example

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Supply chain

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Supply chain

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Supply chain

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Supply chain

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Supply chain

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How to identify a good library Looks alive Built for required platform Easy to use, hard to misuse Covered with tests Documentation Secure Performance Licence

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https://snyk.io/advisor/npm-package/ react-native-sensitive-info How to identify a good library

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Useful tools Automate and add to PRs SonarQube Snyk Dependabot

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Useful tools Automate and add to PRs SonarQube Snyk Dependabot SAST (Static Application Security Testing): https://owasp.org/www-community/ Source_Code_Analysis_Tools DAST (Dynamic Application Security Testing): https://owasp.org/www-community/ Vulnerability_Scanning_Tools

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User is a single point of failure Non-custodial wallets security is the user responsibility.

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Useful links [Article] Crypto wallets security as seen by security engineers: https://www.cossacklabs.com/blog/crypto-wallets-security/ [Article] Security of React Native libraries: the bad, the worse and the ugly: https://www.cossacklabs.com/blog/react-native-libraries-security/ [Article] React Native security: things to keep in mind: https://www.cossacklabs.com/blog/react-native-app-security/ [Slides] Why can’t developers make it secure: https://speakerdeck.com/julep/why-cant-developers-make-it-secure

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Thank you! Follow me on Twitter @julepka