Users' data security in iOS applications

* Why should we think about security at all.

* How to protect the users' data. Why shouldn't we store passwords. Encrypt database: it is necessary or too lazy to do that?

* How to transfer data to the server in a safe way. What is MitM attack?

* What is password protection? Why snapshots and pasteboard are dangerous?

Talk at Odessa Innovation Week, WebCamp 2015.

Transcript

1. U S E R S ’ D ATA S E C U R I T Y I N I O S A P P L I C A T I O N S Odessa Innovation Week, WebCamp 2015
2. W H AT I S U S E R D ATA Odessa Innovation Week, WebCamp 2015 User data is being generated during interactions with user
3. I T I S A D E V E L O P E R ’ S R E S P O N S I B I L I T Y T O P R O T E C T S E N S I T I V E D ATA Odessa Innovation Week, WebCamp 2015
4. U S E R D ATA S TAT E S Odessa Innovation Week, WebCamp 2015 • Runtime data • Stored data • Transmitted data
5. W H AT C O U L D P O S S I B LY G O W R O N G ? Odessa Innovation Week, WebCamp 2015 • Runtime data • Stored data • Transmitted data C O U L D B E S T O L E N , M O D I F I E D O R D E L E T E D
6. W H AT S H O U L D W E D O ? Odessa Innovation Week, WebCamp 2015 • Runtime data • Stored data • Transmitted data encrypt storage encrypt transport use secure design
7. R U N T I M E D ATA Odessa Innovation Week, WebCamp 2015
8. U I PA S T E B O A R D • general Pasteboard is open for everyone Odessa Innovation Week, WebCamp 2015 [[UIPasteboard generalPasteboard] setValue:@"1234 5689 3455 6604" forPasteboardType:@"card"]; • custom Pasteboards are open for current app and apps with same team ID UIPasteboard * pasteboard = [UIPasteboard pasteboardWithName:@"my.app" create:YES];
 pasteboard.persistent = YES; 
 [pasteboard setValue:@"1234 5689 3455 6604”forPasteboardType:@"card"];
9. U I PA S T E B O A R D • prevent copying sensitive data Odessa Innovation Week, WebCamp 2015 @implementation UITextView (DisableCopyPaste)
 
 
 - (BOOL)canPerformAction:(SEL)action withSender:(id)sender { 
 [UIMenuController sharedMenuController].menuVisible = NO;
 return NO;
 }
 
 @end
10. S N A P S H O T T I N G & S C R E E N S H O T T I N G Odessa Innovation Week, WebCamp 2015 - (void)applicationWillResignActive:(UIApplication *)application { 
 UIImageView * imageView = [[UIImageView alloc]initWithFrame: [self.window frame]];
 [imageView setImage:[UIImage imageNamed:@"mySplash"]];
 [self.window addSubview:imageView]; 
 } • hide any sensitive data before snapshotting • or set your picture as snapshot - (void)applicationWillResignActive:(UIApplication *)application { 
 self.window.rootViewController.view.cardLabel.hidden = YES;
 }
11. PA S S W O R D - P R O T E C T I O N Odessa Innovation Week, WebCamp 2015 • ask password on app launching (if it’s really needed) • ask password on entering ‘sensitive’ areas • ask password to confirm some actions • ask password on configuration screen
12. T O U C H I D iOS8+ LocalAuthentication Framework use as alternative to your application’s password Odessa Innovation Week, WebCamp 2015
13. T O U C H I D #import <LocalAuthentication/LocalAuthentication.h> LAContext * myContext = [LAContext new];
 NSError * authError = nil;
 NSString * myLocalizedReasonString = @"Authenticate using your finger";
 
 
 if ([myContext canEvaluatePolicy:LAPolicyDevice OwnerAuthenticationWithBiometrics error:&authError]) {
 
 ...
 } else {
 NSLog(@"Authentication error %@", authError); } Odessa Innovation Week, WebCamp 2015
14. T O U C H I D [myContext evaluatePolicy: LAPolicyDeviceOwnerAuthenticationWithBiometrics
 localizedReason:myLocalizedReasonString
 reply:^(BOOL success, NSError * error) { 
 if (success) {
 NSLog(@"User is authenticated successfully”);
 } else {
 NSLog(@"Authentication failed with error %@", error); }
 }];
 Odessa Innovation Week, WebCamp 2015
15. T O U C H I D switch (error.code) { 
 case LAErrorAuthenticationFailed:
 NSLog(@"Authentication Failed");
 break;
 
 case LAErrorUserCancel:
 NSLog(@"User pressed Cancel button");
 break;
 
 case LAErrorUserFallback:
 NSLog(@"User pressed \"Enter Password\"");
 [self showPassword];
 break;
 
 default:
 NSLog(@"Touch ID is not configured");
 [self showPassword];
 break;
 } Odessa Innovation Week, WebCamp 2015
16. S T O R E D D ATA Odessa Innovation Week, WebCamp 2015
17. D O N O T S T O R E • passwords • keys • any financial data • logs! Odessa Innovation Week, WebCamp 2015
18. P L A I N T E X T K E Y S A R E B A D Odessa Innovation Week, WebCamp 2015 [Parse setApplicationId:@"GpvoqI7Ut29H...2JL1dyceOv0hV1" 
 clientKey:@“sv8wcfIf0neo...y2m9YIwu0OxQr”]; static NSString *kMyAPIKey = @"mySecretApiKey";
19. P L A I N T E X T K E Y S A R E B A D Odessa Innovation Week, WebCamp 2015 strings MyApp.app/MyApp > myapp.txt
20. P L A I N T E X T K E Y S A R E B A D Odessa Innovation Week, WebCamp 2015 GpvoqI7Ut29...2JL1dyceOv0hV1 sv8wcfIf0neo...y2m9YIwu0OxQr application did finish launching window T@"UIWindow",&,N T@"UIWindow",&,N,V_window [Parse setApplicationId:@"GpvoqI7Ut29H...2JL1dyceOv0hV1" 
 clientKey:@“sv8wcfIf0neo...y2m9YIwu0OxQr”]; static NSString *kMyAPIKey = @"mySecretApiKey";
21. AV O I D P L A I N T E X T K E Y S • store like hex strings Odessa Innovation Week, WebCamp 2015 unsigned char myApiKey[] = { 0xAB, 0xAA, 0xBE, 0xDE, 0xEF }; • obfuscate 
 NSString * key = [NSString stringWithFormat:@"%@%@%@%@", @"my", @"secret", @"Api", @“Key"]; 
 NSString * key = [NSString stringWithFormat:@"%3$@%2$@%1$@%4$@", @"Api", @"secret", @"my", @"Key"]; NSString * format = [[[@"x3$yx2$z%1$yx4$@"
 stringByReplacingOccurrencesOfString:@"x" withString:@"%"]
 stringByReplacingOccurrencesOfString:@"y" withString:@"@"]
 stringByReplacingOccurrencesOfString:@"z" withString:@"@"];
 NSString * key = [NSString stringWithFormat:format, @"Api", @"secret", @"my", @"Key"]; "mySecretApiKey"
22. U S E E N C RY P T E D K E Y S 1. take key in plain text Odessa Innovation Week, WebCamp 2015 static NSString *kMyAPIKey = @"mySecretApiKey"; NSData * encryptedData = [RNEncryptor encryptData:kMyAPIKey
 withSettings:kRNCryptorAES256Settings
 password:[self calculatePassword]
 error:&error]; 
 NSString * resultString = [[NSString alloc] initWithData:encryptedData encoding:NSUTF8StringEncoding]; 2. encrypt it
23. U S E E N C RY P T E D K E Y S 3. hardcode encrypted key Odessa Innovation Week, WebCamp 2015 static NSString *kMyAPIKeyEncrypted = @“789fae43c3e66113e48cebfafeef6806542c0c9062b78b686f515acb0 9b2c0a6"; NSData *decryptedData = [RNDecryptor decryptData:encryptedData
 withPassword:[self calculatePassword]
 error:&error]; NSString * resultString = [[NSString alloc] initWithData:encryptedData encoding:NSUTF8StringEncoding]; 4. decrypt it before using
24. U S E E N C RY P T E D K E Y S 5. use generated password, not static string Odessa Innovation Week, WebCamp 2015 - (NSString * )calculatePassword {
 CGFloat result = (CGFloat) (1.0/23.0);
 return [NSString stringWithFormat:@"%.10f", result];
 } @“0.0434782609” this password is calculated each time; is not stored as string
25. W H E R E T O S T O R E S E N S I T I V E D ATA ? • NSUserDefaults • plist • files • database • keychain Odessa Innovation Week, WebCamp 2015
26. W H E R E T O S T O R E S E N S I T I V E D ATA ? • NSUserDefaults • plist • files • database • keychain Odessa Innovation Week, WebCamp 2015 U S E K E Y C H A I N
27. W H E R E T O S T O R E S E N S I T I V E D ATA ? • NSUserDefaults • plist • files • database • keychain Odessa Innovation Week, WebCamp 2015 O R U S E E N C RY P T I O N !
28. E N C RY P T A L L D ATA C O M M O N C RY P T O F R A M E W O R K Odessa Innovation Week, WebCamp 2015
29. E N C RY P T A L L D ATA #import <CommonCrypto/CommonCryptor.h> - (NSData *)AES256EncryptWithKey:(NSString*)key {
 char keyPtr[kCCKeySizeAES256 + 1]; // room for terminator (unused)
 bzero(keyPtr, sizeof(keyPtr)); // fill with zeroes (for padding)
 
 [key getCString:keyPtr maxLength:sizeof(keyPtr) encoding:NSUTF8StringEncoding];
 
 NSUInteger dataLength = [self length];
 
 size_t bufferSize = dataLength + kCCBlockSizeAES128;
 void* buffer = malloc(bufferSize);
 
 size_t numBytesEncrypted = 0;
 CCCryptorStatus cryptStatus = CCCrypt(kCCEncrypt, kCCAlgorithmAES128, kCCOptionPKCS7Padding,
 keyPtr, kCCKeySizeAES256,
 NULL
 [self bytes], dataLength, /* input */
 buffer, bufferSize, /* output */
 &numBytesEncrypted);
 
 if (cryptStatus == kCCSuccess) {
 //the returned NSData takes ownership of the buffer and will free it on deallocation
 return [NSData dataWithBytesNoCopy:buffer length:numBytesEncrypted];
 }
 
 free(buffer);
 return nil;
 } Odessa Innovation Week, WebCamp 2015 C O M M O N C RY P T O
30. E N C RY P T A L L D ATA #import <CommonCrypto/CommonCryptor.h> - (NSData *)AES256EncryptWithKey:(NSString*)key {
 char keyPtr[kCCKeySizeAES256 + 1]; // room for terminator (unused)
 bzero(keyPtr, sizeof(keyPtr)); // fill with zeroes (for padding)
 
 [key getCString:keyPtr maxLength:sizeof(keyPtr) encoding:NSUTF8StringEncoding];
 
 NSUInteger dataLength = [self length];
 
 size_t bufferSize = dataLength + kCCBlockSizeAES128;
 void* buffer = malloc(bufferSize);
 
 size_t numBytesEncrypted = 0;
 CCCryptorStatus cryptStatus = CCCrypt(kCCEncrypt, kCCAlgorithmAES128, kCCOptionPKCS7Padding,
 keyPtr, kCCKeySizeAES256,
 NULL
 [self bytes], dataLength, /* input */
 buffer, bufferSize, /* output */
 &numBytesEncrypted);
 
 if (cryptStatus == kCCSuccess) {
 //the returned NSData takes ownership of the buffer and will free it on deallocation
 return [NSData dataWithBytesNoCopy:buffer length:numBytesEncrypted];
 }
 
 free(buffer);
 return nil;
 } Odessa Innovation Week, WebCamp 2015 C O M M O N C RY P T O
31. E N C RY P T A L L D ATA #import <RNCryptor/RNCryptor.h>
 
 NSData *data = [@"Data" dataUsingEncoding:NSUTF8StringEncoding];
 NSError *error;
 NSData *encryptedData = [RNEncryptor encryptData:data
 withSettings:kRNCryptorAES256Settings
 password:aPassword
 error:&error]; 
 NSData *decryptedData = [RNDecryptor decryptData:encryptedData
 withPassword:aPassword
 error:&error]; Odessa Innovation Week, WebCamp 2015 https://github.com/RNCryptor/RNCryptor U S E W R A P P E R S
32. E N C RY P T A L L D ATA 
 #import "scell_seal.h" NSData *data = [@"Data" dataUsingEncoding:NSUTF8StringEncoding]; TSCellSeal * cellSeal = [[TSCellSeal alloc] initWithKey:masterKeyData];
 NSData * encryptedMessage = [cellSeal wrapData:data context:nil error:&error];
 
 NSData * decryptedMessage = [cellSeal unwrapData:encryptedMessage
 context:nil
 error:&error]; Odessa Innovation Week, WebCamp 2015 https://github.com/cossacklabs/themis U S E C O O L L I B R A R I E S
33. E N C RY P T D ATA B A S E SQLCipher (+FMDB) https://github.com/sqlcipher/sqlcipher CoreData https://github.com/project-imas/encrypted-core- data Odessa Innovation Week, WebCamp 2015
34. F I L E S P R O T E C T I O N Odessa Innovation Week, WebCamp 2015 allows to encrypt NSFiles
35. Odessa Innovation Week, WebCamp 2015 * NSFileProtectionNone * NSFileProtectionComplete Cannot be accessed while device locked. * NSFileProtectionCompleteUnlessOpen Opens only when device is unlocked; can be accessed whenever * NSFileProtectionCompleteUntilFirstUserAuthentication Opens only after device is booted; can be accessed whenever. F I L E S P R O T E C T I O N
36. Odessa Innovation Week, WebCamp 2015 NSFileManager * fileManager = [NSFileManager defaultManager]; 
 NSDictionary * attributes = @{ NSFileProtectionKey : NSFileProtectionComplete };
 
 [fileManager createFileAtPath:path
 contents:data
 attributes:attributes];
 
 
 [fileManager setAttributes:attributes
 ofItemAtPath:path
 error:&errorFolderProtect]; F I L E S P R O T E C T I O N
37. Odessa Innovation Week, WebCamp 2015 [SSKeychain setPassword:password 
 forService:@"com.my.app" 
 account:@"MyAppUserPasswordKey"]; S E C U R E K E Y C H A I N https://github.com/soffes/sskeychain S E C U R I T Y F R A M E W O R K O R U S E W R A P P E R S
38. D I S A B L E D E B U G G I N G Y O U R A P P S Odessa Innovation Week, WebCamp 2015 typedef int (*ptrace_ptr_t)(int _request, pid_t _pid, caddr_t _addr, int _data); 
 #if !defined(PT_DENY_ATTACH)
 #define PT_DENY_ATTACH 31
 #endif
 
 void disable_gdb() {
 void* handle = dlopen(0, RTLD_GLOBAL | RTLD_NOW);
 ptrace_ptr_t ptrace_ptr = dlsym(handle, "ptrace");
 ptrace_ptr(PT_DENY_ATTACH, 0, 0, 0);
 dlclose(handle);
 }
 int main(int argc, char * argv[]) { 
 #if !(DEBUG) // Don't interfere with Xcode debugging sessions.
 disable_gdb();
 #endif
 
 @autoreleasepool { 
 return UIApplicationMain(argc, argv, nil, NSStringFromClass([AppDelegate class]));
 }
 } https://www.theiphonewiki.com/wiki/Bugging_Debuggers
39. T R A N S M I T T E D D ATA Odessa Innovation Week, WebCamp 2015
40. S E N D I N G P L A I N T E X T D ATA • plain text could be easily stolen or modified • sending passwords as plain text is bad idea Odessa Innovation Week, WebCamp 2015
41. S E N D I N G P L A I N T E X T D ATA • plain text could be easily stolen or modified • sending passwords as plain text is bad idea Odessa Innovation Week, WebCamp 2015 U S E H T T P S !
42. Odessa Innovation Week, WebCamp 2015
43. U S I N G H T T P S Odessa Innovation Week, WebCamp 2015 HTTPs protects only POST requests (do not use GET*) * https://blog.httpwatch.com/2009/02/20/how- secure-are-query-strings-over-https/
44. U S I N G H T T P S : B A D P R A C T I C E S • allowing self-signed certificates Odessa Innovation Week, WebCamp 2015 - (void)connection:(NSURLConnection *)connection didReceiveAuthenticationChallenge:(NSURLAuthenticationChallenge *)challenge { 
 [challenge.sender continueWithoutCredentialForAuthenticationChallenge:challenge];
 } 
 [AFSecurityPolicy setAllowInvalidCertificates:YES];
 [AFSecurityPolicy setValidatesDomainName:NO]; • allowing invalid certificates
45. U S I N G H T T P S : B A D P R A C T I C E S • allowing self-signed certificates Odessa Innovation Week, WebCamp 2015 - (void)connection:(NSURLConnection *)connection didReceiveAuthenticationChallenge:(NSURLAuthenticationChallenge *)challenge { 
 [challenge.sender continueWithoutCredentialForAuthenticationChallenge:challenge];
 } 
 [AFSecurityPolicy setAllowInvalidCertificates:YES];
 [AFSecurityPolicy setValidatesDomainName:NO]; • allowing invalid certificates A F N E T W O R K I N G B U G S 2 . 5 . 1 - 2 . 5 . 2
46. H T T P S O N I O S 9 H T T P I S T U R N E D O F F ! Odessa Innovation Week, WebCamp 2015 (as required by App Transport Security)
47. H T T P S O N I O S 9 H T T P I S T U R N E D O F F ! Odessa Innovation Week, WebCamp 2015 you should disable ATS to use HTTP (as required by App Transport Security)
48. H T T P S O N I O S 9 H T T P I S T U R N E D O F F ! Odessa Innovation Week, WebCamp 2015 you should disable ATS to use HTTP (as required by App Transport Security)
49. U S I N G H T T P S : B A D P R A C T I C E S H T T P S D O E S N ’ T M E A N T O U S E P L A I N T E X T Odessa Innovation Week, WebCamp 2015
50. U S I N G H T T P S : B A D P R A C T I C E S H T T P S D O E S N ’ T M E A N T O U S E P L A I N T E X T Odessa Innovation Week, WebCamp 2015 anyone can generate fake SSL certificate and your app will trust him MitM attacks lead to stolen or modified data
51. H T T P S I S N O T S O S E C U R E A L L D ATA S H O U L D B E E N C RY P T E D Odessa Innovation Week, WebCamp 2015 For messaging you should use special crypto, not just encrypting data like for storage.
52. E N C RY P T I N G C O M M U N I C AT I O N Odessa Innovation Week, WebCamp 2015 Communication is sequence of messages
53. E N C RY P T I N G C O M M U N I C AT I O N Odessa Innovation Week, WebCamp 2015 Communication is sequence of messages When sequence get’s recorded, it is easier to crack the key based on captured data
54. E N C RY P T I N G C O M M U N I C AT I O N Odessa Innovation Week, WebCamp 2015 Communication is sequence of messages When sequence get’s recorded, it is easier to crack the key based on captured data Your keys should be ephemeral, your exchange should be sequence aware, authenticated and content- validating
55. E N C RY P T I N G C O M M U N I C AT I O N Odessa Innovation Week, WebCamp 2015 Communication is sequence of messages When sequence get’s recorded, it is easier to crack the key based on captured data Your keys should be ephemeral, your exchange should be sequence aware, authenticated and content- validating E N D T O E N D P E R F E C T F O R WA R D S E C R E C Y P R O N E T O T I M I N G AT TA C K S AUTHENTICATE M ESSAGES U S E K E Y A G R E E M E N T P R O T O C O L
56. E N C RY P T I N G C O M M U N I C AT I O N Odessa Innovation Week, WebCamp 2015 Communication is sequence of messages When sequence get’s recorded, it is easier to crack the key based on captured data Your keys should be ephemeral, your exchange should be sequence aware, authenticated and content- validating E N D T O E N D P E R F E C T F O R WA R D S E C R E C Y P R O N E T O T I M I N G AT TA C K S AUTHENTICATE M ESSAGES U S E K E Y A G R E E M E N T P R O T O C O L
57. E N C RY P T I N G C O M M U N I C AT I O N Odessa Innovation Week, WebCamp 2015 Themis (Secure Message / Secure Session) (https://github.com/cossacklabs/themis) OTRKit (https://github.com/ChatSecure/OTRKit) libsodium / NaCL (https://github.com/mochtu/ libsodium-ios) T H E R E ’ S A L I B F O R T H AT !
58. M O R E T O R E A D Odessa Innovation Week, WebCamp 2015 • The Mobile Application Hacker's Handbook • https://books.google.com.ua/books? id=UgVhBgAAQBAJ • Secure Developing on iOS • https://www.isecpartners.com/media/11221/ secure_development_on_ios.pdf
59. M O R E T O R E A D Odessa Innovation Week, WebCamp 2015 • Security Coding Guide • https://developer.apple.com/library/ios/ documentation/Security/Conceptual/ SecureCodingGuide/Introduction.html#// apple_ref/doc/uid/TP40002477-SW1
60. M O R E T O R E A D Odessa Innovation Week, WebCamp 2015 • Designing Secure User Interfaces • https://developer.apple.com/library/ios/ documentation/Security/Conceptual/ SecureCodingGuide/Articles/ AppInterfaces.html#//apple_ref/doc/uid/ TP40002862-SW1
61. M O R E T O R E A D Odessa Innovation Week, WebCamp 2015 • https://www.theiphonewiki.com/wiki/ Bugging_Debuggers • http://www.splinter.com.au/2014/09/16/storing- secret-keys/ • http://priyaaank.tumblr.com/post/81172916565/ validating-ssl-certificates-in-mobile-apps • https://www.venafi.com/blog/post/ssl- vulnerabilities-in-your-mobile-apps-what-could- possibly-go-wrong
62. L A S T S L I D E @vixentael Odessa Innovation Week, WebCamp 2015 Anastasi, iOS dev @ Stanfy