What is the RBF file format?
Files with the .rbf extension contain backup copies of files that are overwritten during a software installation. Windows Installer (msiexec.exe), operating on Microsoft Windows, is responsible for creating .rbf files. These files preserve all data that will be replaced or modified during the installation process.
At the beginning of installation, the original versions of any files being overwritten are copied into .rbf backup files and stored in the hidden Config.msi folder at the root of the target drive (for example, C:\Config.msi\). In addition, a paired .rbs file is generated, which contains the rollback script that directs how the backed-up data should be restored. If the installation completes successfully, both the .rbf and .rbs files are automatically deleted from the hard drive.
In the event of an error or an interrupted installation, the data from the .rbf files is restored to its original location. This method ensures that even if a software installation fails partway through, already-functioning applications are not damaged.
The Config.msi folder is normally hidden and restricted to SYSTEM-level access to prevent tampering during the installation process.
Security & safety
RISK: LOWRBF files are raw binary backups of legitimate system files created by Windows Installer. They are not executable and not a malware vector by themselves. The Config.msi folder is a known location that some malware may attempt to abuse via race conditions (CVE-2017-0100 family) - but the .rbf files themselves are benign backups.
Format details
in a nutshell- Rebirth RB-338 preset file - Propellerhead ReBirth RB-338 (discontinued 2005) used .rbf for synthesizer preset files.
- Router firmware binary - Some router manufacturers (e.g. TP-Link, D-Link) use .rbf for firmware update binary images.
Programs that open RBF files
Windows1 app
Microsoft Windows (automatic)
Built-in RBF files are used automatically by Windows Installer; no manual opening is needed or useful. Delete leftover files in Config.msi after confirming installation is not in progress. Technical details
deep spec| Format type | Proprietary binary backup file (Windows Installer internal format) |
| MIME type | application/octet-stream (no registered type) |
| Encoding | Binary |
| Byte order | Little-endian |
| Compression | None - files are raw binary copies of the originals |
| Typical file size | Bytes to hundreds of MB (depends on the size of files overwritten during installation) |
| Storage location | C:\Config.msi\ (hidden folder at the root of the installation target drive; SYSTEM-only access) |
| Paired file | .rbs rollback script that directs how .rbf backup data is applied during rollback |
| Created by | Windows Installer (msiexec.exe) automatically at the start of each MSI installation |
| Lifecycle | Automatically deleted when installation completes successfully; retained only on failure or interruption |
| Associated operating system | Windows (all versions supporting Windows Installer) |
| Introduced with | Windows Installer 1.0, included in Windows 2000 (released February 2000) |
| Security note | Config.msi folder is SYSTEM-access-only; race conditions in earlier builds (e.g. CVE-2017-0100) allowed privilege escalation, patched in later Windows 10 versions |
| Released | 1999 (Windows Installer 1.0, Windows 2000) |
| Specification | learn.microsoft.com |
RBF conversions
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