CBC File

What are CBC files and how to open them

Are you having problems opening a CBC file or are you simply curious about its contents? We're here to explain the properties of these files and provide you with software that can open or handle your CBC files.

What is a CBC file?

A .CBC file is a Clam Antivirus ByteCode Signatures file.

Clam Antivirus ByteCode Signatures files provide a way to define malware-detection rules that run code rather than just matching fixed patterns. They are used with ClamAV's signature database: when ClamAV is updating its "bytecode" signature database (named like "bytecode.cvd" or "bytecode.cld"), the bytecode signatures inside are stored as ASCII-encoded files with a .cbc extension. These signatures allow authors to write C-language functions that examine parts of files past simple pattern matching to detect more complex threat characteristics.

The .cbc format is created using ClamAV's bytecode compiler project, which compiles user-written signature source into bytecode. ClamAV then loads these bytecode functions when scanning; the functions are provided APIs to access the file being scanned and any metadata ClamAV already has. When conditions are met, the bytecode function can flag the sample as malicious with a specific signature name. Only trusted bytecode (for example those published by the official sources) is loaded by default; untrusted bytecode must be explicitly enabled.

Internally a .cbc file begins with the ASCII header "ClamBC" at offset zero.

How to open CBC files

Important: Different programs may use files with the CBC file extension for different purposes, so unless you are sure which format your CBC file is, you may need to try a few different programs.

While we have not verified the apps ourselves yet, our users have suggested four different CBC openers which you will find listed below.

Last updated: August 31, 2026

Various apps that use files with this extension

These apps are known to open certain types of CBC files. Remember, different programs may use CBC files for different purposes, so you may need to try out a few of them to be able to open your specific file.

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