De Rebus Antiquis (DRA) is an exploit in iOS 7's iBoot that abuses a recursive stack overflow bug. The exploit was developed by xerub. Tools such as powdersn0w Archived 2022-07-20 at the Wayback Machine can use this to achieve untethered downgrades on any 32-bit device you have iOS 7.1.x SHSH blobs saved for. This is most useful on the iPhone 4.
DRA is not available on 64-bit devices. It was patched in iOS 8 but may work on iOS 6 or earlier.
See also[edit source]
- iOS 5 HFS Heap Buffer Overflow, another iBoot exploit that could be used for untethered downgrades