OpenSSL Universal Patcher | Eamon Woortman

The Problem

Besiege on the Xbox PC/Microsoft Store platform crashes for users with specific hardware specifications. This is caused by a bug in the Unity 5.4.0f3 Editor (and builds made with it) where apps that use OpenSSL (i.e., secure web requests) crash on 10th and 11th gen Intel CPUs.

The Solution

The OpenSSL Universal Patcher is a command-line tool designed to patch 64-bit Windows binary executables that are linked to an older version of OpenSSL (1.1.0). It resolves crashes on 10th and 11th gen Intel CPUs and improves the overall stability and security of the affected binaries.

How It Works

The patcher replaces specific x86-64 assembly instructions to redirect register usage, fixing the compatibility issue at the binary level:

# lea     rax, [rsi+40h]
original: 48 8D 46 40
# lea     r8, [rsi+40h]
patched: 4C 8D 46 40
# 4 bytes from the previous instruction
offset: 4
# cmovnz  rsi, rax
original: 48 0F 45 F0
# cmovnz  rsi, r8
patched: 49 0F 45 F0

The patch that changes 2 OpenSSL specific instructions.

Example usage on Unity Editor, Unreal game and Besiege game executables

I wrote a blog post about creating a patch, so check out this article if you're interested.

GitHub Blog Post