It appears some people have been experiencing issues when trying to run Apple’s iBooks app on jailbroken devices, specifically the ones done via recently released GreenPois0n. Today though, iOS hacking king Comex tweeted that he has discovered the reason for the crash, and can now start to implement a fix.
@Comex: It seems that before opening a DRMed book, iBooks drops an improperly signed binary, tries to execute it, and if it works concludes that the device is jailbroken and refuses to open the book.
This is what the binary does:
int main() {
return 42;
}
Later, MuscleNerd of iPhone Dev Team also confirmed the fix:
@comex did an amazingly fast job repairing the damage Apple did to iBooks on JB platforms (fairplayd is next cat&mouse?)
The issue stems from the way iBooks handles DRM protected books. According to Comex, the app actually checks to see if the device is jailbroken by trying to execute an improperly signed binary. If it works, the application knows the hardware has been jailbroken and the book isn’t opened.
Perhaps the question here is why is Apple checking for jailbroken hardware? Hopefully it’s just an anti-piracy measure but the cynic in me thinks there may be more to it than that. Even if it is a piracy issue, I’m sure jailbreakers won’t take too kindly to Apple assuming they are all pirating content!
Comex has said that the fix will be added to the next jailbreak tool for iOS, so hopefully the issue will be a thing of the past very soon.
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