OWASP ZHYTOMYR. 29 JUNE 2019. JULIA POTAPENKO TOUCH ID AND FACE ID IS IT SECURE?

OWASP ZHYTOMYR. 29 JUNE 2019. JULIA POTAPENKO TOUCH ID AND FACE ID IS IT SECURE? Cats Edition

JULIA POTAPENKO • iOS Software Engineer at Stuzo • Mobile Dev Lead at WWCode Kyiv • Co-organizer of OWASP Zhytomyr • Speaker at OWASP, CocoaHeads, WWCode and WTM events

WE WILL TALK ABOUT ★ Touch ID and Face ID ★ Secure Enclave ★ Keychain

WE WILL TALK ABOUT ★ Touch ID and Face ID ★ Secure Enclave ★ Keychain How to do it? What can go wrong?

TOUCH ID AND FACE ID LOCAL AUTHENTICATION

TOUCH ID AND FACE ID LOCAL AUTHENTICATION USER PROTECTED RESOURCES PROTECTED ACTIONS

LOCAL AUTHENTICATION https://support.apple.com/en-us/HT204587 https://developer.apple.com/documentation/localauthentication

SECURE ENCLAVE CREATE AN EXTRA LAYER OF SECURITY FOR YOUR PRIVATE KEYS. https://developer.apple.com/documentation/security/certificate_key_and_trust_services/keys/ storing_keys_in_the_secure_enclave

SECURE ENCLAVE • A part of A7 and newer chips • Secure Enclave Processor (SEP) is separate from Application Processor (AP) • Shares the RAM with AP but encrypted (TZ0) • SEP has its own OS

SECURE ENCLAVE • Stores only 256-bit elliptic curve private keys • Can’t import preexisting keys You can create private key, store it and perform operations on it.

• Biometry is stored on device as mathematical representation • It is encrypted with a private key stored in Secure Enclave • Biometry data is used by Secure Enclave only • It can’t be accessed by OS or any application

LocalAuthentication • Specify a particular policy and user message • The framework coordinates with Secure Enclave • Validation returns boolean value

LocalAuthentication • Specify a particular policy and user message • The framework coordinates with Secure Enclave • Validation returns boolean value WARNING

LAContext *myContext = [[LAContext alloc] init]; NSError *authError = nil; NSString *myLocalizedReasonString = @"For Securing App with TouchID"; if ([myContext canEvaluatePolicy:LAPolicyDeviceOwnerAuthenticationWithBiometrics error:&authError]) { [myContext evaluatePolicy:LAPolicyDeviceOwnerAuthenticationWithBiometrics localizedReason:myLocalizedReasonString reply:^(BOOL) success, NSError *error) { if (success) { // User authenticated successfully } else { // User failed to authenticate successfully } }]; } else { // Could not evaluate policy https://nvisium.com/blog/2016/06/22/dont-touch-me-that-way.html LocalAuthentication

LAContext *myContext = [[LAContext alloc] init]; NSError *authError = nil; NSString *myLocalizedReasonString = @"For Securing App with TouchID"; if ([myContext canEvaluatePolicy:LAPolicyDeviceOwnerAuthenticationWithBiometrics error:&authError]) { [myContext evaluatePolicy:LAPolicyDeviceOwnerAuthenticationWithBiometrics localizedReason:myLocalizedReasonString reply:^(BOOL) success, NSError *error) { if (success) { // User authenticated successfully } else { // User failed to authenticate successfully } }]; } else { // Could not evaluate policy https://nvisium.com/blog/2016/06/22/dont-touch-me-that-way.html LocalAuthentication

LAContext *myContext = [[LAContext alloc] init]; NSError *authError = nil; NSString *myLocalizedReasonString = @"For Securing App with TouchID"; if ([myContext canEvaluatePolicy:LAPolicyDeviceOwnerAuthenticationWithBiometrics error:&authError]) { [myContext evaluatePolicy:LAPolicyDeviceOwnerAuthenticationWithBiometrics localizedReason:myLocalizedReasonString reply:^(BOOL) success, NSError *error) { if (success) { // User authenticated successfully } else { // User failed to authenticate successfully } }]; } else { // Could not evaluate policy https://nvisium.com/blog/2016/06/22/dont-touch-me-that-way.html VULNERABLE AGAINST REVERSE ENGINEERS LocalAuthentication

LAContext *myContext = [[LAContext alloc] init]; NSError *authError = nil; NSString *myLocalizedReasonString = @"For Securing App with TouchID"; if ([myContext canEvaluatePolicy:LAPolicyDeviceOwnerAuthenticationWithBiometrics error:&authError]) { [myContext evaluatePolicy:LAPolicyDeviceOwnerAuthenticationWithBiometrics localizedReason:myLocalizedReasonString reply:^(BOOL) success, NSError *error) { if (success) { // User authenticated successfully } else { // User failed to authenticate successfully } }]; } else { // Could not evaluate policy https://nvisium.com/blog/2016/06/22/dont-touch-me-that-way.html VULNERABLE AGAINST REVERSE ENGINEERS LocalAuthentication USABLE PAYLOAD

KEYCHAIN

KEYCHAIN • A database storing encrypted items • Good for storing passwords, tokens, not for files • Each item is protected by passcode/biometry and device secret • Keychain items are available when user authenticates to the device

No content

THE CORRECT FLOW EXAMPLE • The user secret is stored in Keychain. • When the protected action is triggered, Keychain should be unlocked with Touch ID to get the secret. • BE should enforce the client to include that secret when the protected action is performed.

THE CORRECT FLOW EXAMPLE • The user secret is stored in Keychain. • When the protected action is triggered, Keychain should be unlocked with Touch ID to get the secret. • BE should enforce the client to include that secret when the protected action is performed. WHAT ELSE CAN GO WRONG?

KEYCHAIN • Accessibility and authentication rules

KEYCHAIN • Accessibility and authentication rules SecAccessControlRef • kSecAccessControlTouchIDAny – Use any of the registered fingerprints • kSecAccessControlTouchIDCurrentSet – Use the current set of fingerprints when data saved to keychain. If current set changes, the TouchID evaluation fails.

No content

ANY VULNERABILITIES IN SECURE ENCLAVE?

https://twitter.com/xerub/status/897896081874329600 HACKER CLAIMS TO HAVE DECRYPTED SECURE ENCLAVE

https://twitter.com/xerub/status/897896081874329600 HACKER CLAIMS TO HAVE DECRYPTED SECURE ENCLAVE

https://youtu.be/ei6NWGfRs2o Apple Secure Enclave Processor Hack Explained • Firmware decryption key for iPhone 5s only

IS IT SECURE? ★ Chance that someone else fingerprint will unlock you device is 1 in 50 000 ★ For Face ID it is 1 in 1 000 000 https://images.apple.com/business/docs/FaceID_Security_Guide.pdf

IS IT SECURE? ★ Chance that someone else fingerprint will unlock you device is 1 in 50 000 ★ For Face ID it is 1 in 1 000 000 ★ To compare: 4 digit passcode has 1 in 10 000 chance while 6 digit passcode has 1 in 1 000 000 https://images.apple.com/business/docs/FaceID_Security_Guide.pdf

TOUCH ID AND FACE ID ARE VULNERABLE AGAINST TARGETED ATTACKS https://youtu.be/2u4ZLGsw1zo

No content

WHERE TO GO NEXT OWASP MSTG – Testing Local Authentication https://github.com/OWASP/owasp-mstg/blob/master/Document/0x06f-Testing-Local- Authentication.md iOS Security Guide https://www.apple.com/business/site/docs/iOS_Security_Guide.pdf WWDC 14 – Keychain and Authentication with Touch ID https://devstreaming-cdn.apple.com/videos/wwdc/ 2014/711xx6j5wzufu78/711/711_keychain_and_authentication_with_touch_id.pdf David Lindner – Don’t Touch Me That Way https://nvisium.com/blog/2016/06/22/dont-touch-me-that-way.html

https://speakerdeck.com/julep/ owasp-mstg-in-real-life https://speakerdeck.com/julep/owasp- mstg-when-authentication-goes-wrong OTHER TALKS https://www.facebook.com/julia.potapenko.16 https://t.me/OWASP_ZHYTOMYR_CHAT

THANK YOU!