Supported File Types

The following file types and extensions are currently supported by Glasswall. Glasswall offers two levels of CDR for our supported file types.

Comprehensive

Glasswall extrapolates the file to its granular levels, then inspects and validates every component, their relationships, and their attributes in accordance with the file vendor specification.

File Type	Extension(s)
Word Binary File	.doc, .dot
Excel Binary File	.xls, .xlt
PowerPoint Binary File	.ppt, .pps, .pot
PDF Document	.pdf
Office Open XML Document	.docx, .docm, .dotx, .dotm
Office Open XML Workbook	.xlsx, .xltx, .xltm, .xlsm
Office Open XML Presentation	.pptx, .pptm, .ppsx, .ppam, .potm, .ppsm, .potx
TIFF Image	.tif, .tiff, .geotiff
SVG Image	.svg
Enhanced Meta File	.emf
Windows Metafile Format	.wmf
JPEG Image	.jpeg, .jpg, .jpe, .jif, .jfif, .jfi
PNG Image	.png
GIF Image	.gif
BMP Image	.bmp, .dib

Standard

Glasswall extrapolates the file at a high level (e.g., container level), then validates these components against a subset of selected rules from the file vendor specification. For example, Glasswall may validate attributes of a container and ensure that the streams are of the correct size, running order, and encoding in relation to the container metadata. However, the contents of these streams are not further inspected, validated, or cleansed.

File Type	Extension(s)
WebP Image	.webp
Waveform Audio File	.wav, .wave
MPEG-2 Media File	.mpg, .mpeg
MP3 Audio File	.mp1, .mp2, .mp3
MP4 Media File	.mp4, .m4a, .m4p, .m4b, .m4r, .m4v

Supported File size

Glasswall provides 64-bit version of a Dynamic-link Libraries (.DLL) for Windows and/or Shared Objects (.SO) for Linux operating systems that can analyse and protect files up to the size of 2GiB (2,147,483,648 bytes), provided that other internal limits (such as recursion depth) are satisfied.

Special Cases and Limitations

Multiple Formats

Embedded Files and Embedded Images

Where possible, embedded files and embedded images will be processed as standalone files independently of the containing file. The exceptions to this are as follows:

• The embedded file is not recognised or is not supported by the Glasswall engine
• The embedded file is obfuscated by the containing file in such a way that its contents is inaccessible to the Glasswall engine
• The content management policy for the containing file has the corresponding switch (embedded_files or embedded images) set to disallow

For more information about how each of these cases is dealt with, see Content Management.

Binary Office

Macros

When set to sanitise, the macros content management switch removes the VBA script from the regenerated file but preserves the macro storage container. This can give the impression that the macros are still present in the file when validating based on the regenerated file entries.

Limitations

Office 95 and earlier versions are not supported. If these file types are processed, they will cause an Issue to be reported in the XML report (in Analysis Mode) and the file will not be regenerated in Protect Mode.

Binary Office files containing Apple Mac or LibreOffice specific file features may be marked as non-conforming.

If a digital signature is found within a Binary Office file, the file will be rejected to avoid compromising the integrity of the file.

Office Open XML

Limitations

Office files containing Apple Mac or LibreOffice specific file features may be marked as non-conforming or the components may be removed from the file.

If a digital signature is found within an OfficeXML file, the file will be rejected to avoid compromising the integrity of the file.

Encrypted Files

Limitations

Glasswall does not currently provide the ability to decrypt files, therefore encrypted files are not supported and are marked as non-conforming and blocked by default.

MathType Equation Format (MTEF)

Basic support for version 3 and 5 currently supported. Further documentation on the format is here:

https://docs.wiris.com/en/mathtype/office_tools/mathtype-sdk/mtefstorage https://rtf2latex2e.sourceforge.net/MTEF3.html

Non-CDR Formats

Archive Support

For the Embedded Engine SDK, we recommend that integrators explode archives before presenting files for CDR processing.

Glasswall Halo provides archive support. Archive formats and file types are first identified using a structural check and then decompressed. Glasswall Halo provides REST API endpoints that that can accept both single and archive files.

This overview describes how the Glasswall Halo solution provides a configurable ruleset for how archives are processed.

Plain Text Files

Plain text files using UTF-8 or ASCII encoding are only supported by the filetype detection functionality and by Word Search when enable_text_support is specified true under sysConfig. Attempting to run analysis or protect on a plain text file will result in the file being reported as unsupported and blocked.

Binary formats

Binary executable files should be used with caution and the use of additional security filters is highly recommended.

Binary files are inspected at the container level where headers, sections and metadata are validated against the relevant standard, however binary files may still be risky in nature given a full decompilation is not performed to reverse engineer any source code.

The table below specifies the binary formats that the Embedded Engine will inspect and validate at the container level only.

File Type	Extension(s)
Windows Portable Executable Format	.acm, .ax, .cpl, .dll, .drv, .mui, .exe, .ocx, .scr, .sys, .efi, .tsp
Mach Object Format (Mach-O)	.o, .dylib
Common Object File Format	.o, .obj
Executable & Linked Format	.elf, .o, .so, .axf, .bin, .ko, .mod, .out