I just hacked your app - AppBuilders Switzerland 2017

Android security is nowhere near where it should be. I have been able to hack and get sensitive information from a few different apps and I’m just an amateur hacker at best.

In this session we will explore a number of ways an Android app can be exploited and most importantly methods that we can use to avoid these attacks.

Transcript

1. I just hacked your app
2. Watch this
4. PWNED
5. Marcos Placona @marcos_placona marcos@twilio.com github.com/mplacona androidsecurity.info
6. NOT
8. Lorem ipsum dolor sit amet, consectetur adipiscing elit. Vestibulum euismod ipsum et semper vestibulum. In congue, risus ac lobortis commodo, arcu elit congue nisi, e ullamcorper diam quam in est. Quisque nec lectus eget metus pharetra placerat. Quisque nisi lorem, convallis eget lobortis quis, suscipit eu sem. Sed ligula purus, lacinia quis ultrices at, sollicitudin at lacus. Duis porta hendrerit semper. Sed vitae mauris fringilla, porta turpis facilisis, facilisis risus. Integer quis lobortis velit. Vivamu ut placerat ex. Nunc est purus, pretium vitae hendrerit fringilla, molestie at tortor. Vestibulum vel purus et urna hendrerit pretium et quis nunc. Fusce sit amet neque in justo elementum rutrum ut nec metus. Fusce sollicitudin, dui vel molestie aliquam, ligula leo fringilla augue, a luctus quam sem sed tortor. Vivamus mattis nisi purus, si amet efficitur lectus mollis nec. Etiam consectetur, nisl eu euismod posuere, justo neque vehicula ex, nec lobortis augue neque id mi. Ut aliquam odio ac turpis condimentum porttitor. Mauris ut est eu sapien tempor congue. Proin ipsum sem, cursus quis magna eu, finibus fringilla nulla. Vestibulum viverra felis ac arcu iaculis condimentum. Aenean mattis magna non ipsum viverra accumsan. Suspendisse potenti. Nam quis dapibus ipsum. Integer at tortor ac neque semper consectetur. Donec vitae mattis felis, quis
9. elementum dolor fringilla eu. Nulla luctus arcu et egestas ultrices. Quisque dignissim lacinia vehicula. Suspendisse vitae nisl dapibus, dapibus elit quis, efficitur ex. Done interdum est purus, nec tempor risus sollicitudin tincidunt. Vestibulum accumsan sed libero ut tincidunt. Interdum et malesuada fames ac ante ipsum primis in faucibus. Vestibulum vitae consectetur ex, vitae viverra felis. Sed vitae imperdiet turpis. Donec eget velit sagittis, hendrerit ante id, aliquet libero. Proin pulvinar ornare consectetur. Vestibulum ante ipsum primis in faucibus orci luctus et ultrices posuere cubilia Curae; Proin consequat tincidunt risus et aliquam. Donec vel vulputate sem, sed ornare lorem. Curabitur a maximus urna, ut blandit tellus. Suspendisse I haven’t nisl a ultricies semper. Cras really purus mollis vestibulum rhoncus. Sed hacked your orci, imperdiet vitae pharetra app, tincidunt laoreet lacus Vivamus posuere nisl diam, ut efficitur mauris facilisis vehicula. Vestibulum risus veli tincidunt a libero a, vestibulum tincidunt orci. Pellentesque in finibus est. Praesent tempus tortor ac magna iaculis, sed cursus quam venenatis. Quisque pharetra euismod auctor.
10. Sue-y /s(j)uːi/ 1. To become annoyed with someone who broke your toy without permission and want to sue them for that. “Company X got all ‘sue-y’ on me when I hacked their app and showed the world"
14. Kuba Gretzki http://bit.ly/hack4beer
15. loyalty \ˈlȯi(-ə)l-tē\
16. loyalty + =
17. loyalty HTTP Proxy
18. POST /users/461845f5d03e6c052a43afbc/points Accept: application/json Accept-Language: en-gb X-App-Version: 1.28.0 User-Agent: Dalvik/2.1.0 (Linux; U; Android 6.0.1;) ... Content-Type: application/json; charset=UTF-8 Content-Length: 375 Host: api.eatapp.com Connection: Keep-Alive Accept-Encoding: gzip { "authentication_token":"boKUp9vBHNAJp7XbWZCK", "latitude":..., "longitude":..., "point":{ "isDoneByGesture":false, "main_beacon":{ "major":38995, "minor":12702, "uuid":"2C75E74B-41B7-49E3-BD26-CE86B2F569F8" }, "place_id":"450", "promoted_products_ids":[ {"id":"647035946536601578040000"}, {"id":"647035946536601578040000"}, {"id":"647035946536601578050000"} ] } }
19. POST /users/461845f5d03e6c052a43afbc/points Accept: application/json Accept-Language: en-gb X-App-Version: 1.28.0 User-Agent: Dalvik/2.1.0 (Linux; U; Android 6.0.1;) ... Content-Type: application/json; charset=UTF-8 Content-Length: 375 Host: api.eatapp.com Connection: Keep-Alive Accept-Encoding: gzip { "authentication_token":"boKUp9vBHNAJp7XbWZCK", "latitude":..., "longitude":..., "point":{ "isDoneByGesture":false, "main_beacon":{ "major":38995, "minor":12702, "uuid":"2C75E74B-41B7-49E3-BD26-CE86B2F569F8" }, "place_id":"450", "promoted_products_ids":[ {"id":"647035946536601578040000"}, {"id":"647035946536601578040000"}, {"id":"647035946536601578050000"} ] } }
20. POST /users/461845f5d03e6c052a43afbc/points Accept: application/json Accept-Language: en-gb X-App-Version: 1.28.0 User-Agent: Dalvik/2.1.0 (Linux; U; Android 6.0.1;) ... Content-Type: application/json; charset=UTF-8 Content-Length: 375 Host: api.eatapp.com Connection: Keep-Alive Accept-Encoding: gzip { "authentication_token":"boKUp9vBHNAJp7XbWZCK", "latitude":..., "longitude":..., "point":{ "isDoneByGesture":false, "main_beacon":{ "major":38995, "minor":12702, "uuid":"2C75E74B-41B7-49E3-BD26-CE86B2F569F8" }, "place_id":"450", "promoted_products_ids":[ {"id":"647035946536601578040000"}, {"id":"647035946536601578040000"}, {"id":"647035946536601578050000"} ] } }
24. stop!
25. • Encrypt all the values • Utilise security features when they exist • Certificate pinning • DO NOT TRUST THE DEVICE
26. Encrypt all the values dependencies { compile 'com.scottyab:aescrypt:0.0.1' } String password = "password"; String message = "hello world"; try { String encryptedMsg = AESCrypt.encrypt(password, message); }catch (GeneralSecurityException e){ //handle error } String password = "password"; String encryptedMsg = "2B22cS3UC5s35WBihLBo8w=="; try { String messageAfterDecrypt = AESCrypt.decrypt(password, encryptedMsg); }catch (GeneralSecurityException e){ //handle error - could be due to incorrect password or tampered encryptedMsg }
27. • Encrypt all the values • Utilise security features when they exist • Certificate pinning • DO NOT TRUST THE DEVICE
28. Utilise security features when they exist
29. • Encrypt all the values • Utilise security features when they exist • Certificate pinning • DO NOT TRUST THE DEVICE
30. Certificate pinning String hostname = "publicobject.com"; CertificatePinner certificatePinner = new CertificatePinner.Builder() .add(hostname, "sha256/AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA=") .build(); OkHttpClient client = OkHttpClient.Builder() .certificatePinner(certificatePinner) .build(); Request request = new Request.Builder() .url("https://" + hostname) .build(); client.newCall(request).execute(); http://bit.ly/android-certificate-pinning
31. Certificate pinning String hostname = "publicobject.com"; CertificatePinner certificatePinner = new CertificatePinner.Builder() .add(hostname, "sha256/AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA=") .build(); OkHttpClient client = OkHttpClient.Builder() .certificatePinner(certificatePinner) .build(); Request request = new Request.Builder() .url("https://" + hostname) .build(); client.newCall(request).execute(); http://bit.ly/android-certificate-pinning
32. Certificate pinning String hostname = "publicobject.com"; CertificatePinner certificatePinner = new CertificatePinner.Builder() .add(hostname, "sha256/AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA=") .build(); OkHttpClient client = OkHttpClient.Builder() .certificatePinner(certificatePinner) .build(); Request request = new Request.Builder() .url("https://" + hostname) .build(); client.newCall(request).execute(); http://bit.ly/android-certificate-pinning
33. • Encrypt all the values • Utilise security features when they exist • Certificate pinning • DO NOT TRUST THE DEVICE
34. Someone will decompile your app
35. And when they do…
36. –Every Developer “But I need magic strings”
37. Options http://bit.ly/SafeKey Encrypt Make sure you encrypt or at least encode them Server Get your keys of a server you own
38. Store in the NDK http://bit.ly/NDKStorage
39. start!
40. • Add tampering detection • Check your app’s signature • Check for rooted device • Check for emulator • Check if the app is debuggable
41. Tampering detection // myPackageName should decode at runtime to "com.yourpackagename" // google should decode at runtime to "com.android.vending"; // amazon should decode at runtime to "com.amazon.venezia"; public boolean isHacked(Context context, String myPackageName, String google, String amazon) { //Crooks renamed your app? if (context.getPackageName().compareTo(myPackageName != 0) return true; // BOOM! //Rogues relocated your app? String installer = context.getPackageManager().getInstallerPackageName(myPackageName); if (installer == null) return true; // BOOM! if (installer.compareTo(google) != 0 && installer.compareTo(amazon) != 0) return true; // BOOM! return false; } http://bit.ly/android-tampering-detection
42. Tampering detection // myPackageName should decode at runtime to "com.yourpackagename" // google should decode at runtime to "com.android.vending"; // amazon should decode at runtime to "com.amazon.venezia"; public boolean isHacked(Context context, String myPackageName, String google, String amazon) { //Crooks renamed your app? if (context.getPackageName().compareTo(myPackageName != 0) return true; // BOOM! //Rogues relocated your app? String installer = context.getPackageManager().getInstallerPackageName(myPackageName); if (installer == null) return true; // BOOM! if (installer.compareTo(google) != 0 && installer.compareTo(amazon) != 0) return true; // BOOM! return false; } http://bit.ly/android-tampering-detection
43. • Add tampering detection • Check your app’s signature • Check for rooted device • Check for emulator • Check if the app is debuggable
44. private static final int VALID = 0; private static final int INVALID = 1; private static final String APP_SIGNATURE = "1038C0E34658923C4192E61B16846"; public static int checkAppSignature(Context context) { try { PackageInfo packageInfo = context.getPackageManager() .getPackageInfo(context.getPackageName(), PackageManager.GET_SIGNATURES); for (Signature signature : packageInfo.signatures) { byte[] signatureBytes = signature.toByteArray(); MessageDigest md = MessageDigest.getInstance("SHA"); md.update(signature.toByteArray()); //compare signatures if (SIGNATURE.equals(APP_SIGNATURE)){ return VALID; }; } } catch (Exception e) { //assumes an issue in checking signature., but we let the caller decide on what to do. } return INVALID; } Check your app’s signature http://bit.ly/AndroidTampering
45. • Add tampering detection • Check your app’s signature • Check for rooted device • Check for emulator • Check if the app is debuggable
46. private static boolean canExecuteCommand(String command) { try { int exitValue = Runtime.getRuntime().exec(command).waitFor(); if (exitValue != 0) return false; else return true; } catch (Exception e) { return false; } } Check for rooted device
47. • Add tampering detection • Check your app’s signature • Check for rooted device • Check for emulator • Check if the app is debuggable
48. Build.FINGERPRINT.startsWith("generic") Check for emulator
49. • Add tampering detection • Check your app’s signature • Check for rooted device • Check for emulator • Check if the app is debuggable
50. public static boolean isDebuggable(Context context){ return (context.getApplicationInfo().flags & ApplicationInfo.FLAG_DEBUGGABLE) != 0; } Check if the app is debuggable
51. Debuggable app
53. Things to look at • Protect your apps with tools like ProGuard and DexGuard. • Look at the SafetyNet API by Google • Implement Network Security Configuration http://bit.ly/SafeKey
54. ProGuard DexGuard • Installed by default • Name Obfuscation • Code Optimisation • Removal of Redundant Code • FREE • Class Encryption • Call Hiding through Reflection • String Encryption • Certificate Checks • Debug Detection • Emulator Detection • Root Detection • Tamper Detection • Costs $$$
55. Things to look at • Protect your apps with tools like ProGuard and DexGuard. • Look at the SafetyNet API by Google • Implement Network Security Configuration http://bit.ly/SafeKey
56. SafetyNet API by Google
57. Things to look at • Protect your apps with tools like ProGuard and DexGuard. • Look at the SafetyNet API by Google • Implement Network Security Configuration http://bit.ly/SafeKey
58. Network Security Configuration
61. Marcos Placona @marcos_placona marcos@twilio.com Thanks github.com/mplacona androidsecurity.info