swipswaps/bat2exe

Convert batch files into executables to prevent tampering of scripts.

bat2exe

Convert batch files into executables to prevent tampering of scripts.

Implementation

The builder program takes a batch file as input, and extracts an embedded executable called the stub to the disk. The builder then updates the resources of the stub so that there is a resource in the stub containing the contents of the batch file. It then renames the stub so that it has the same name as the batch file (sans the .bat extension).

When the stub is executed, it will extract its embedded batch file to the temp folder, and then run the file. When the batch file is done executing, it will be deleted from the temp folder.

You may notice that there is a file called msvcrt.lib and msvcrt.exp indicating that I linked against msvcrt.dll which is unsupported by Microsoft. The full explanation for this can be found in stub\main.cpp, but I will summarize it here. Basically I wanted to create an executable with no dependency on the C runtime to reduce the size of the stub. However, no matter what I did, I could not optimize out calls to memset(...), and the linker was complaining that it could not find the implementation of it since I told the linker not to include the C runtime. After many hours of trial and failure, I gave up and decided I would accept linking up against msvcrt.dll so that the linker would shut up. However, since linking against msvcrt.dll is unsupported, Microsoft does not supply a .lib file to link against, and I could not use LoadLibrary(...) and GetProcAddress(...) because the memset(...) that kept being called was not explicitly called by me, but rather inserted by the compiler (even after I disabled optimizations). Thus, I had to create my own msvcrt.lib which I did by following the instructions at https://stackoverflow.com/a/9946390.

Limitations

The embedded batch file is stored as a plaintext resource, so it is possible to open the stub in a text editor and see the contents of the script.

To Do List

• Use XOR or some other algorithm to ensure that embedded batch file is not visible in plaintext.
• Support administrator manifest.
• Support password requirement to launch batch file.
• Anti-tamper checksum (and other anti-tampering techniques, i don't know what though).
• Clean up random file name generator (I think it generates the same random name each time).