| Installer / Format | Compression Methods Supported | |--------------------|-------------------------------| | InnoSetup (v5.x, v6.x) | aPLib, LZMA, zlib (deflate) | | InstallShield (v11+) | zlib, LZX, CabLZ | | MSI (Embedded CABs) | LZMA, zlib | | Custom game archives | Generic chunk detection (heuristic) |
Unlike generic archivers, xtool targets specific chunk-based compression methods (e.g., aPLib, LZMA, zlib) used inside installer stubs, decompressing them so that a repackager can later apply more efficient compression. | Feature | Description | |---------|-------------| | Precompression | Decompresses existing compressed blocks inside an installer executable or data file. | | Chunk detection | Automatically finds and extracts compressed streams based on known signatures (e.g., aP for aPLib, LZMA headers). | | Recompression support | Prepares data for tools like FreeArc or 7-Zip to recompress with stronger algorithms. | | Integrity preservation | Maintains original offsets and alignment to avoid breaking installer checksums or overlay signatures. | razor12911 xtool precompression tool
Report ID: RE-XTOOL-2025-01 Subject: Analysis of xtool – a precompression and repackaging utility for executable installers Author: Security Research Unit Date: April 14, 2026 1. Executive Summary xtool is a command-line utility developed by the programmer razor12911 (active in communities such as ZenHAX and CS.RIN.RU). Its primary function is to act as a precompressor – a tool that processes compressed data streams within proprietary installer setups (e.g., InnoSetup, InstallShield) to allow recompression with higher ratios or to enable modification of precompressed archives. | Installer / Format | Compression Methods Supported
xtool --mode=precompress --in=game_setup.exe --out=precompressed.dat xtool --mode=extract-chunks --in=precompressed.dat --outdir=chunks/ After recompressing chunks externally: | | Recompression support | Prepares data for