How do I detect that an iOS app is running on a jailbroken phone?

Question

If I want my app to behave differently on a jailbroken iPhone, how would I go about determining this?

Answer 1

You can detect if a device is JailBroken or not by checking for the following:

• Cydia is installed
• Verify some of the system paths
• Perform a sandbox integrity check
• Perform symlink verification
• Verify whether you create and write files outside your Sandbox

There is an open source library I created from various articles and books. Try it out on GitHub!

Answer 2

+(BOOL)isJailbroken {
    NSURL* url = [NSURL URLWithString:@"cydia://package/com.example.package"];
    return [[UIApplication sharedApplication] canOpenURL:url];
}

Checking the file path /Applications/Cydia.app is not allowed on a normal phone? I've never heard of Apple detecting this and rejecting an app for it, but Apple is unpredictable. Cydia has a URL scheme cydia:// which can be legally checked with UIApplication canOpenURL:

Answer 3

I reworked in Swift 2.3 the solution provided by @Yossi

public static func jailbroken(application: UIApplication) -> Bool {
    guard let cydiaUrlScheme = NSURL(string: "cydia://package/com.example.package") else { return isJailbroken() }
    return application.canOpenURL(cydiaUrlScheme) || isJailbroken()
}


static func isJailbroken() -> Bool {

    if isSimulator {
        return false
    }

    let fileManager = NSFileManager.defaultManager()
    if fileManager.fileExistsAtPath("/Applications/Cydia.app") ||
        fileManager.fileExistsAtPath("/Library/MobileSubstrate/MobileSubstrate.dylib") ||
        fileManager.fileExistsAtPath("/bin/bash") ||
        fileManager.fileExistsAtPath("/usr/sbin/sshd") ||
        fileManager.fileExistsAtPath("/etc/apt") ||
        fileManager.fileExistsAtPath("/usr/bin/ssh") {
        return true
    }

    if canOpen("/Applications/Cydia.app") ||
        canOpen("/Library/MobileSubstrate/MobileSubstrate.dylib") ||
        canOpen("/bin/bash") ||
        canOpen("/usr/sbin/sshd") ||
        canOpen("/etc/apt") ||
        canOpen("/usr/bin/ssh") {
        return true
    }

    let path = "/private/" + NSUUID().UUIDString
    do {
        try "anyString".writeToFile(path, atomically: true, encoding: NSUTF8StringEncoding)
        try fileManager.removeItemAtPath(path)
        return true
    } catch {
        return false
    }
}

static func canOpen(path: String) -> Bool {
    let file = fopen(path, "r")
    guard file != nil else { return false }
    fclose(file)
    return true
}

Answer 4

I am not aware of any "APIs" that exist for this. If there were, then a jailbreak-masking product would quickly cover them up.

As lots of people point out, it is a cat-and-mouse game. And after both players become expert, it all comes down to who gets the first move. (Person holding the device.)

I found many good suggestions for detecting jailbreak in Zdziarski's new book "Hacking and Securing iOS Apps". (Personally, I paid more for the O'Reilly eBook because they permit copy-and-paste.)

No, I am not affiliated with the publishers. But I did find it a good book. I don't like to just publish hackers' mistakes so they can fix them, so I thought I'd point to the book.

Answer 5

The most sophisticated method I know is using objc_copyImageNames() function. It returns a list of currently loaded libraries and since most people have MobileSubstrate on jailbroken devices and most iAP crack tools depend on it, at least some MobileSubstrate libraries will show up.

Answer 6

This is a code that combine some answers I found for this need, and will give you much higher success rate :

BOOL isJailbroken()
{
#if !(TARGET_IPHONE_SIMULATOR)

   if ([[NSFileManager defaultManager] fileExistsAtPath:@"/Applications/Cydia.app"] ||
       [[NSFileManager defaultManager] fileExistsAtPath:@"/Library/MobileSubstrate/MobileSubstrate.dylib"] ||
       [[NSFileManager defaultManager] fileExistsAtPath:@"/bin/bash"] ||
       [[NSFileManager defaultManager] fileExistsAtPath:@"/usr/sbin/sshd"] ||
       [[NSFileManager defaultManager] fileExistsAtPath:@"/etc/apt"] ||
       [[NSFileManager defaultManager] fileExistsAtPath:@"/private/var/lib/apt/"] ||
       [[UIApplication sharedApplication] canOpenURL:[NSURL URLWithString:@"cydia://package/com.example.package"]])  {
         return YES;
   }

   FILE *f = NULL ;
   if ((f = fopen("/bin/bash", "r")) ||
      (f = fopen("/Applications/Cydia.app", "r")) ||
      (f = fopen("/Library/MobileSubstrate/MobileSubstrate.dylib", "r")) ||
      (f = fopen("/usr/sbin/sshd", "r")) ||
      (f = fopen("/etc/apt", "r")))  {
         fclose(f);
         return YES;
   }
   fclose(f);

   NSError *error;
   NSString *stringToBeWritten = @"This is a test.";
   [stringToBeWritten writeToFile:@"/private/jailbreak.txt" atomically:YES encoding:NSUTF8StringEncoding error:&error];
   [[NSFileManager defaultManager] removeItemAtPath:@"/private/jailbreak.txt" error:nil];
   if(error == nil)
   {
      return YES;
   }

#endif

   return NO;
}