Sometimes you'll run into a situation where you need to patch a binary file. bytepatcher is a small utility writen in Go which can be used when you know the signature and patch hex.
bytepatcher was created as a learning project.
If you are a Go user you can run go install github.com/shindakun/bytepatcher. Prebuilt binaries are not currently provided.
$ ./bytepatcher -in string input filename -out string output filename -patch string patch hex as string -sig string signature as string
For a very basic example, say we need to change a JE (74) to a JMP (EB) in an executable file.
$ bytepatcher -in file.exe -out patched.exe -sig 83F8057441 -patch 83F805EB41
2018/01/17 13:20:00 Signature: 83f8057441
2018/01/17 13:20:00 Patch: 83f805eb41
2018/01/17 13:20:00 Found signature at 0x5e3!
2018/01/17 13:20:00 Wrote 5 bytes!
2018/01/17 13:20:00 Saved output!You'll note we used a long signature and patch, this is because we wanted to patch one specific location in the file. If we had used a shorter signature we would potentially patch in the wrong spot. Also it is worth noting that currently we're only able to patch a single location. So, even though we're writing 5 bytes we're really only patching 1.