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

BOOL isJailbroken()
{
#if TARGET_IPHONE_SIMULATOR
    return NO;
#else
    FILE *f = fopen("/bin/bash", "r");

    if (errno == ENOENT)
    {
        // device is NOT jailbroken
        fclose(f);
        return NO;
    }
    else {
        // device IS jailbroken
        fclose(f);
        return YES;
    }
#endif
}

Answer 2

It depends what you mean by jailbreak. In the simple case, you should be able to see if Cydia is installed and go by that - something like

NSString *filePath = @"/Applications/Cydia.app";
if ([[NSFileManager defaultManager] fileExistsAtPath:filePath])
{
   // do something useful
}

For hacked kernels, it's a little (lot) more involved.

Answer 3

Please use following code for Swift 4 and above: Add the following code in the appdelegate:

private func getJailbrokenStatus() -> Bool {
    if TARGET_IPHONE_SIMULATOR != 1 {
        // Check 1 : existence of files that are common for jailbroken devices
        if FileManager.default.fileExists(atPath: "/Applications/Cydia.app")
            || FileManager.default.fileExists(atPath: "/Library/MobileSubstrate/MobileSubstrate.dylib")
            || FileManager.default.fileExists(atPath: "/bin/bash")
            || FileManager.default.fileExists(atPath: "/usr/sbin/sshd")
            || FileManager.default.fileExists(atPath: "/etc/apt")
            || FileManager.default.fileExists(atPath: "/private/var/lib/apt/")
            || UIApplication.shared.canOpenURL(URL(string:"cydia://package/com.example.package")!) {
            return true
        }
        // Check 2 : Reading and writing in system directories (sandbox violation)
        let stringToWrite = "Jailbreak Test"
        do {
            try stringToWrite.write(toFile:"/private/JailbreakTest.txt", atomically:true, encoding:String.Encoding.utf8)
            //Device is jailbroken
            return true
        } catch {
            return false
        }
    }
    else {
        return false
    }
}

func applicationDidBecomeActive (_ application: UIApplication) {

    if getJailbrokenStatus() {
        let alert = UIAlertController(title: LocalizedKeys.Errors.jailbreakError, message: LocalizedKeys.Errors.jailbreakErrorMessage, preferredStyle: UIAlertController.Style.alert)
        let jailBrokenView = UIViewController()

        jailBrokenView.view.frame = UIScreen.main.bounds
        jailBrokenView.view.backgroundColor = .white
        self.window?.rootViewController = jailBrokenView
        jailBrokenView.present(alert, animated: true, completion: nil)
    }

    if #available(iOS 11.0, *) {
        if !UIScreen.main.isCaptured {
            DispatchQueue.main.async {
                self.blockImageView.removeFromSuperview()
            }
        }
    }
}

Answer 4

I'd suggest looking for files that aren't present on a "vanilla" iPhone. All jailbreak kits I've seen install ssh. That might be a good indicator of a jailbroken phone.

Answer 5

Try to find a file which cydia or jailbroken device create. Or try to write in a file outside the app's blackbox. If you succeed to do that, the device is compromised/jailbroken :)

- (BOOL)jailbroken
{
    NSFileManager * fileManager = [NSFileManager defaultManager];
    return [fileManager fileExistsAtPath:@"/private/var/lib/apt/"];
}