Thursday, July 22, 2021

ClamAV 0.104.0 Release Candidate is here!

We are pleased to announce the ClamAV 0.104.0 release candidate.

Please help us validate this release. We need your feedback, so let us know what you find and join us on the ClamAV mailing list, or on our Discord.

This release candidate phase is only expected to last about two to four weeks before the 0.104.0 Stable version will be published. Take this opportunity to verify that you 0.104.0 can build and run in your environment. 

Please submit bug reports to the ClamAV project GitHub Issues.  

ClamAV 0.104.0 includes the following improvements and changes.

New Requirements

  • As of ClamAV 0.104, CMake is required to build ClamAV.

  • We have added comprehensive build instructions for using CMake to the new file. The online documentation will also be updated to include CMake build instructions.
  • The Autotools and the Visual Studio build systems have been removed.

Major changes

  • The built-in LLVM for the bytecode runtime has been removed.

  • The bytecode interpreter is the default runtime for bytecode signatures just as it was in ClamAV 0.103.
  • We wished to add support for newer versions of LLVM, but ran out of time. If you're building ClamAV from source and you wish to use LLVM instead of the bytecode interpreter, you will need to supply the development libraries for LLVM version 3.6.2. See to learn more.
  • There are now official ClamAV images on Docker Hub.

    • Note: Until ClamAV 0.104.0 is released, these images are limited to "unstable" versions, which are updated daily with the latest changes in the default branch on GitHub.

You can find the images on Docker Hub under clamav.

Docker Hub ClamAV tags:

  • clamav/clamav:<version>: A release preloaded with signature databases.

    Using this container will save the ClamAV project some bandwidth. Use this if you will keep the image around so that you don't download the entire database set every time you start a new container. Updating with FreshClam from the existing databases set does not use much data.

  • clamav/clamav:<version>_base: A release with no signature databases.

    Use this container only if you mount a volume in your container under /var/lib/clamav to persist your signature database databases. This method is the best option because it will reduce data costs for ClamAV and for the Docker registry, but it does require advanced familiarity with Linux and Docker.

    Caution: Using this image without mounting an existing database directory will cause FreshClam to download the entire database set each time you start a new container.

You can use the unstable version (i.e. clamav/clamav:unstable or clamav/clamav:unstable_base) to try the latest from our development branch.

Please, be kind when using "free" bandwidth for the virus databases and Docker registry. Try not to download the entire database set or the larger ClamAV database images on a regular basis.

For more details, see the ClamAV Docker documentation.

Special thanks to Olliver Schinagl for his excellent work creating ClamAV's new Docker files, image database deployment tooling, and user documentation.

  • clamd and freshclam are now available as Windows services. To install and run them, use the --install-service option and net start [name] command.

    Special thanks to Gianluigi Tiesi for his original work on this feature.

Notable changes

We added these features in 0.103.1 but wanted to re-post them here, as patch versions do not generally introduce new options:

  • Added a new scan option to alert on broken media (graphics) file formats. This feature mitigates the risk of malformed media files intended to exploit vulnerabilities in other software. Currently, media validation exists for JPEG, TIFF, PNG, and GIF files. To enable this feature, set AlertBrokenMedia yes in clamd.conf, or use the --alert-broken-media option when using clamscan. These options are disabled by default in this patch, but may be enabled in a subsequent release. Application developers may enable this scan option by enabling CL_SCAN_HEURISTIC_BROKEN_MEDIA for the heuristic scan option bit field.

  • Added CL_TYPE_TIFF, CL_TYPE_JPEG types to match GIF and PNG typing behavior. BMP and JPEG 2000 files will continue to detect as CL_TYPE_GRAPHICS because ClamAV does not have BMP or JPEG 2000 format-checking capabilities.

  • Added progress callbacks to libclamav for:

    • database load: cl_engine_set_clcb_sigload_progress()
    • engine compile: cl_engine_set_clcb_engine_compile_progress()
    • engine free: cl_engine_set_clcb_engine_free_progress()

    These new callbacks enable an application to monitor and estimate load, compile and unload progress. See clamav.h for API details.

  • Added progress bars to ClamScan for the signature load and engine compile steps before a scan begins. The startup progress bars won't be enabled if ClamScan isn't running in a terminal (i.e. if stdout is not a TTY), or if any of these options are used:

    • --debug
    • --quiet
    • --infected
    • --no-summary

Other improvements

  • Added the %f format string option to the ClamD VirusEvent feature to insert the file path of the scan target when a virus event occurs. This supplements the VirusEvent %v option that prints the signature (virus) name. The ClamD VirusEvent feature also provides two environment variables, $CLAM_VIRUSEVENT_FILENAME and $CLAM_VIRUSEVENT_VIRUSNAME for a similar effect. This fix comes courtesy of Vasile Papp.

  • Improvements to the AutoIt extraction module. Patch courtesy of cw2k.

  • Added support for extracting images from Excel *.xls (OLE2) documents.

  • Trusted SHA256-based Authenticode hashes can now be loaded in from *.cat files. See our Authenticode documentation for more info about using *.cat files with *.crb rules to trust signed Windows executables.

Bug fixes

  • Fixed a memory leak affecting logical signatures that use the "byte compare" feature. Patch courtesy of Andrea De Pasquale.

  • Fixed bytecode match evaluation for PDF bytecode hooks in PDF file scans.

  • Other minor bug fixes.


The ClamAV team thanks the following individuals for their code submissions:

  • Alexander Golovach
  • Andrea De Pasquale
  • Andrew Williams
  • Armin Kuster
  • Brian Bergstrand
  • cw2k
  • Duane Waddle
  • Gianluigi Tiesi
  • Jonas Zaddach
  • Kenneth Hau
  • Markus Strehle
  • Olliver Schinagl
  • Orion Poplawski
  • Sergey Valentey
  • Sven Rueß
  • Tom Briden
  • Vasile Papp
  • Yasuhiro Kimura