ImgUtil is a Win32 utility for modifying Android boot images. (It was formerly named "bootutil.exe".)

Often you need to modify a boot image in small ways, e.g. modifying default.prop inside a ramdisk. There are the standard ways to completely take apart a boot image. After modifications, you can pack the image back together again. This is all a bit needless. There is also the problem of trying to save Linux ownership, mode and symlinks on a Windows system. It's easier to just extract what you need, modify it, then replace the original file.

Usage: imgutil [flags] image [file...] /l list files /r replace files /i insert files /a append files /s symlink (target) /d delete files /x extract files /t use file timestamps /m file mode /g group id /u user id /c set command line /v verbose

An example:

C:\>imgutil boot.img /v /x default.prop C:\>your-text-editor default.prop C:\>imgutil boot.img /v /r default.prop

ImgUtil can handle bare ramdisks, Linux style images with ramdisks and Android style images with ramdisks. It can also handle images with DTB segments in them.

Download the executable.