Tutorial:Creating a NOR-only IPSW

This will create an IPSW that only flashes your device's NOR. It will not touch the operating system or NAND.

1. Create a custom IPSW
2. Unpack it, remove rootfs DMG
3. Decrypt the ramdisk (xpwntool) and mount it.
4. Edit options.plist (/usr/local/share/restore/options.plist) on the restore ramdisk:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
   <key>CreateFilesystemPartitions</key>
   <false/>
   <key>UpdateBaseband</key>
   <false/>
   <key>SystemImage</key>
   <false/>
</dict>
</plist>

5. Unmount and reencrypt the restore ramdisk.
6. Repack the IPSW.

NOTE: This technique only works on devices that have an untethered bootrom exploit (Pwnage or 0x24000 Segment Overflow).

The file format that holds iOS and iPod firmware restore images

A firmware image that contains a minimal operating system for certain tasks, named as such because it is stored temporarily in memory rather than permanently on disk

Often used to refer to a jailbreak that reapplies when the device is powered off or rebooted

The first significant code that runs on an iOS device