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PODetect UDID spoofing on the iPhone at runtime
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copied!<p>Jailbroken iPhones get on my nerve as it taints some fundamental APIs on iOS, by using MobileSubstrate.</p> <p><a href="http://www.iphonedevwiki.net/index.php/MobileSubstrate" rel="noreferrer">http://www.iphonedevwiki.net/index.php/MobileSubstrate</a></p> <p>I believe many apps use UDID as a mean to authenticate a device and/or a user since it's semi-automatic and handy, but you should be aware of this problem: UIDevice is not as tamper-proof as it should be. There's an app called UDID Faker, which easily enables you to spoof someone else's UDID at runtime.</p> <p><a href="http://www.iphone-network.net/how-to-fake-udid-on-ios-4/" rel="noreferrer">http://www.iphone-network.net/how-to-fake-udid-on-ios-4/</a></p> <p>Here's the source code of it:</p> <pre><code>// // UDIDFaker.m // UDIDFaker // #include "substrate.h" #define ALog(...) NSLog(@"*** udidfaker: %@", [NSString stringWithFormat:__VA_ARGS__]); #define kConfigPath @"/var/mobile/Library/Preferences/com.Reilly.UDIDFaker.plist" @protocol Hook - (NSString *)orig_uniqueIdentifier; @end NSString *fakeUDID = nil; static NSString *$UIDevice$uniqueIdentifier(UIDevice<Hook> *self, SEL sel) { if(fakeUDID != nil) { ALog(@"fakeUDID %@", fakeUDID); /* if it's a set value, make sure it's sane, and return it; else return the default one */ return ([fakeUDID length] == 40) ? fakeUDID : [self orig_uniqueIdentifier]; } /* ... if it doesn't then return the original UDID */ else { return [self orig_uniqueIdentifier]; } } __attribute__((constructor)) static void udidfakerInitialize() { NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init]; NSString *appsBundleIdentifier = [[NSBundle mainBundle] bundleIdentifier]; ALog(@"Loading UDID Faker into %@", appsBundleIdentifier); NSDictionary *config = [NSDictionary dictionaryWithContentsOfFile: kConfigPath]; fakeUDID = [config objectForKey: appsBundleIdentifier]; [fakeUDID retain]; if(fakeUDID != nil) { ALog(@"Hooking UDID Faker into %@", appsBundleIdentifier); MSHookMessage(objc_getClass("UIDevice"), @selector(uniqueIdentifier), (IMP)&$UIDevice$uniqueIdentifier, "orig_"); } [pool release]; } </code></pre> <p>As you can see, uniqueIdentifier method in the UIDevice class now returns fakeUDID on any apps.</p> <p>It seems that Skype and some other apps detect this sort of taint, but I don't know how to do it.</p> <p>What I wanted to do is: When tainted UIDevice is detected upon launch, alert and exit(0).</p> <p>Ideas?</p>

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