3/26/2023 0 Comments Synalyze it find structure![]() ![]() Interestingly, we get another 16 bytes that precede filename: 54 00 00 00 80 0c 00 00 8e 01 00 00 22 40 51 f0 What do we get when we hexdump 64 bytes from offset 2C (-s 0x2C) into index.fs? Again using hexdump, the command “hexdump -C -s 0x2C -n 64 MessageTable/index.fs” gives us: Let’s assume the value is either just 0x2C or little-endian 0x002c (i.e. The 0x2c at the start can be interpreted in a number of ways depending on the files endianness. Let’s see if we can find a relationship between the data these 16 bytes represent and other data stored in index.fs or crowd.fs. Looking at the data that appears before the first ASCII filename AdventurerMessageData.btb we get the following 16 bytes: 2c 00 00 00 00 00 00 00 7e 0c 00 00 3d ca 44 49 We also see that it’s not simply a list of filenames, as before each filename there’s additional data. Immediately we see what appears to be filenames in ASCII format, the first three being: MessageTable/index.fs using hexdump we get the following output: We’ll be examining both, and how they relate to each other.ĭisplaying the contents of. Notice that each of these folders contain two files: crowd.fs and index.fs. ![]() After some exploration we find folders which may relate to the text displayed onscreen. This gives us a directory structure to explore. Exploring the extracted game file-systemįirst we extract the in-game file-system. If you want to modify the game by changing the text displayed in-game, or provide a translation to an unsupported language, the first step is understanding what files store the text, how it is formatted and how to extract it. This text data is used in the in-game menus and conversations, for example: The files we’re reverse engineering contain a list of entries of the name, length and offset to entries in files used by the game to store encoded text data. ![]() Let us first explore exactly what the file format is, and why to reverse engineer it. ![]() This section walks through reverse engineering one of the file formats from a game, by building a grammar to describe it, and prettifying the data using memgram. Reversing a Game Text File-System Introduction Here’s an example table of some test prettified data: Memgram is heavily inspired by the GUI hex editors: memgram applies these grammars at offsets in files and displays formatted, prettified output of data based on the grammar. Custom data structures can be quickly described in an easily readable TOML-compliant format called a grammar. Memgram was built to help describe and visualise data structures and files when reverse engineering. Hacking video games for retro consoles first got me into security, hopefully this walk-through will provide insight into some of the techniques involved in reverse engineering file formats, and in using our new tool. To show its capabilities we walk though using it to help reverse engineer a file format for a popular video game. It is specified that the attribute byte count should be set to zero.This blog provides an introduction to our newly developed open-source command-line interface (CLI) binary analysis tool called memgram. The unit vectors along x-axis, y-axis and z-axis are represented by i, j and k respectively. In cartesian system, any vector is represented in terms of its unit vectors. Number of Triangles (facets) - 4-byte little endian unsigned integer STL binary format uses es the IEEE integer and floating point numerical representation. Grammar for Binary STL (stereolithography) files ![]()
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