File Types Supported

Overview

The table below lists the file formats fully supported by Glasswall Rebuild. 'Fully supported' means that the files are subject to inspection at a very low level.

File Extension

Sub Type(s)

Document Type

.pdf

 

PDF documents

.jpg

 

JPEG image files

.gif

 

GIF image files

.png

 

PNG image files

.emf

 

EMF image files

.wmf

 

WMF image files

.tif .tiff, GeoTIFF TIFF image files
.bmp   BMP image files

.doc

.dot

Word Binary File Format files

.xls

.xlt

Excel Binary File Format files

.ppt

.pot

PowerPoint Binary File Format files

.docx

.docm, .dotx, .dotm

Office Open XML Document files

.xlsx

.xlsm, .xltx, .xltm

Office Open XML Workbook files

.pptx

.pptm, .ppsx, .ppam, .potm, .ppsm

Office Open XML Presentation files

 

The table below lists the file formats partially supported by Glasswall Rebuild. 'Partially supported' means that the files are subject to inspection at a high level.

File Extension

Document Type

.mp3

MPEG-1 Audio Layer III (MPEG-2 Audio Layer III) audio files

.mp4

Compressed audio and video digital data files

.mpg

MPEG-1 and MPEG-2 audio and video compression files

.wav

Waveform Audio File Format (WAVE) files

Supported File Sizes

Glasswall Rebuild 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 2 GiB (230 bytes) provided that other internal limits (such as recursion depth) are satisfied.

PDF

Processing Specific to PDF in Protect Mode

PDF is the only file type that allows for an optional watermark to be added to the regenerated file. The watermark is a maximum of 20 (ASCII) characters and is added to the top right hand corner of each page of the regenerated file.

Specification Validated Against

  • PDF Reference (third edition) Adobe Portable Document Format Version 1.7
    Note that Glasswall Rebuild supports PDF Reference (third edition) Adobe Portable Document Format from Version 1.3.

Images

There are no content management switches for any of the image file formats. Images embedded in a document which do not conform to the specification would result in the original document being quarantined.

JPEG

Specification Validated Against

  • JPEG File Interchange Format, Version 1.02 September 1, 1992
  • JP2 for ISO/IEC 15444-1 (JPEG 2000)
  • JPX for ISO/IEC 15444-2 (JPEG 2000)

GIF

Specification Validated Against

  • Graphics Interchange Format, Version GIF 87
  • Graphics Interchange Format, Version GIF 89a

PNG

Specification Validated Against

  • Portable Network Graphics (PNG): Functional specification. ISO/IEC 15948:2003 (E)

EMF

Specification Validated Against

  • [MS-EMF]: Enhanced Metafile Format: Open Specifications Documentation. v20151016
  • [MS-EMFPLUS]: Enhanced Metafile Format Plus Extensions: : Open Specifications Documentation. V20121017

WMF

Specification Validated Against

  • [MS-WMF]: Windows Metafile Format: Open Specifications Documentation. v20121017

TIFF and GeoTIFF

Specification Validated Against

  • TIFF 6.0 Specification: Final – June 3, 1992
  • GeoTIFF Format Specification - Specification Version: 1.8.1

BMP

Specification Validated Against

  • BMP is covered by the WMF file specification.

Binary Office

Processing Specific to Binary Office in Protect Mode

The content management switch GWFILE_MANAGE_REMOVE_MACROS when set to sanitise in Protect mode removes the VBA script from the regenerated file but copies over the macro container. This can give the impression that the macros have not been deleted.

The content management switch GWFILE_MANAGE_REMOVE_EMBEDDED_FILES when set to sanitise in Protect mode do one of two options.

  • If the embedded file is one that Glasswall Rebuild supports it will process that file as if it were a standalone file, including its own configuration management polices if appropriate. If the file can be regenerated the regenerated file will be re-embedded, if it cannot the file it is part of will be marked as non-conforming.
  • If the embedded file is one that Glasswall Rebuild cannot process like a .mdb or .dat file then the embedded file is removed.

Embedded files are validated to five levels deep.

WORD BINARY

Specifications Validated Against

The following specifications are used to validate a Word Binary file format:

  • From [MS-DOC]: Word (.doc) Binary File Format - Microsoft Corporation, 2011, v20121003 to [MS-DOC]: Word (.doc) Binary File Format - Corporation, 2017, v20170112
  • Office Common Data Types and Objects Structure Specification- Microsoft Corporation, 2011, v20110608
  • Office Document Cryptography Structure Specification- Microsoft Corporation, 2011, v20110608
  • Office VBA File Format Structure Specification- Microsoft Corporation, 2011, v20110608

The following files extensions are supported .doc, .dotm and .dot.

Non-supported Specifications 

Word 95 and earlier versions (Word 1 to Word 6) are not supported and if these file types are processed they will cause an Issue to be reported in the XML report in Analysis mode and the file not to be regenerated in Protect mode.

Word files containing Apple Mac or LibreOffice specific file features will be marked as non-conformant.

EXCEL BINARY

Specifications Validated Against

The following specifications are used to validate an Excel Binary file format:

  • From [MS-XLS]: Excel Binary File Format (.xls) Structure Specification - Microsoft Corporation, v20141018 to [MS-XLS]: Excel Binary File Format (.xls) Structure Specification - Microsoft Corporation, v20161017.
  • Spreadsheet Data Model File Format
  • Office Graph Binary File Format v20141019

The following files extensions are supported .xls, .xla, .xlt and .xlsb.

Non-supported Specifications 

Excel 95 and earlier versions are not supported and these file types are processed cause an Issue to be reported in the XML report  in Analysis mode and the file not to be regenerated in Protect mode.

Excel files containing Apple Mac or LibreOffice specific file features will be marked as non-conformant.

POWERPOINT BINARY

Specifications Validated Against

The following specifications are used to validate a PowerPoint binary file format:

  • From [MS-PPT]: PowerPoint (.ppt) Binary File Format - Microsoft Corporation, v20121003 to [MS-PPT]: PowerPoint (.ppt) Binary File Format - Microsoft Corporation, v20160922.

The following files extensions are supported .ppt,  .ppa, .pps, and .pot.

Non-supported Specifications 

PowerPoint 95 and earlier versions are not supported and if these file types are processed it will cause an Issue to be reported in the XML report  in Analysis mode and the file not to be regenerated in Protect mode.

PowerPoint files containing Apple Mac or LibreOffice specific file features will be marked as non conformant.

Office Open XML

Processing Specific to Office Open XML in Protect Mode

If an Office Open XML file has another Office Open XML file embedded inside it and the GWFILE_MANAGE_REMOVE_EMBEDDED_FILES is set to sanitise, the embedded file will be removed when a new file is regenerated.

Office Open XML files are stored as zipped archive files and although the zipped file may be less than 10 MB when the streams are extracted and uncompressed, an individual stream may be greater than 10 MB. When using the 32-bit DLL, streams that are larger than 10 MB cause the file to be marked as non–conforming and are not processed any further. When using the 64-bit DLL, streams of up to 50 MB are processed.

Specifications Validated Against

Office 2010

The following specifications are used to validate Office Open XML (OOXML) Word, Excel, and PowerPoint file types:

Office 2013

The following specifications are used to validate Office Open XML (OOXML) Word, Excel, and PowerPoint file types:

  • Word (.docx) Extensions to the Office Open XML SpreadsheetML File Format
  • Excel (.xlsx) Extensions to the Office Open XML SpreadsheetML File Format
  • PowerPoint  (.pptx) Extensions to the Office Open XML SpreadsheetML File Format
  • Office Drawing Extensions to the Office Open XML Structure

The following files extensions are supported:

  • .docx, .docm, .dotx
  • .xlsx, .xlsm, .xltm, .xltx
  • .pptx, .pptm, .ppsm, .ppam, .ppsx

Non-supported Specifications 

Office 2010 or Office 2013 files containing Apple Mac or LibreOffice specific file features may be marked as non-conformant or the components may be removed from the file.

WAVE

Specifications Validated Against

  • Multimedia Programming Interface and Data Specifications 1.0 August 1991.

The following file extensions are supported:

  • .wav, .wave

MPEG

Specifications Validated Against

  • ISO/IEC 13818-1:2000(E). Information technology — Generic coding of moving pictures and associated audio information: Systems — Part 1 Second edition 2000-12-01

MP3

Specifications Validated Against

MPEG Layer III audio encoding is defined in two ISO/IEC specification families:

  • MPEG-1: ISO/IEC 11172-3. Information technology -- Coding of moving pictures and associated audio for digital storage media at up to about 1.5 Mbit/s -- Part 3: Audio.
  • MPEG-2: ISO/IEC 13818-3. Information technology -- Generic coding of moving pictures and associated audio information -- Part 3: Audio.

MPEG-4

Specification Validated Against

  • ISO/IEC 14496-12:2005(E). Part 12. Information technology — Coding of audio-visual objects — Part 12: ISO base media file format. Corrected version 2005-10-01.

PE and COFF

Specifications Validated Against

  • Microsoft Portable Executable and Common Object File Format Specification Revision 6.0 – February 1999.

ELF

Specifications Validated Against

  • Tool Interface Standard (TIS) Executable and Linking Format (ELF) Specification Version 1.2. May 1995
  • ELF-64 Object File Format Version 1.2 Draft 2. May 27, 1998.

Mach-O

Specifications Validated Against

  • OS X ABI Mach-O File Format Reference. 2009-02-04.