What CAB files are Supported/Non-Supported by MetaDefender’s Deep CDR?

This article applies to all MetaDefender Core V5 and V4 releases deployed on Windows or Linux systems.

It is important to note that, among the archive files with a .cab filename extension, there are actually two distinct file formats, one of which is supported by Metadefender’s Deep CDR, and one of which is not.

The differences between the two .cab formats are outlined below.
Type IDDescriptionSupport to extract
CABMicrosoft Cabinet ArchiveYES
InstallShieldCABInstallShield Cabinet ArchiveNO

1. Microsoft Cabinet, Signature: MSCF

  • Cabinet (or CAB) is a Microsoft Windows archive-file format that supports lossless data compression and embedded digital certificates that are used for maintaining archive integrity.
  • Cabinet files have .cab filename extensions.
  • Cabinet files are recognized by their first 4 bytes: MSCF.
  • Cabinet* files were originally known as Diamond files.

2. InstallShield Cabinet, Signature: ISC

  • InstallShield CAB files are also archive files, but they are used by the installer program, InstallShield for its own proprietary archiving formats. Hence, they are distinct from Microsoft Cabinet files.
  • InstallShield CAB files also have .cab file name extensions.
  • InstallShield CAB file headers are not the same as Microsoft CAB files, so they are incompatible and cannot be manipulated or edited with the programs that are made to interact with the standard Cabinet format - including MetaDefender Core’s Deep CDR.
  • There are actually numerous other (Non-Microsoft) installers that use the .cab extension for their proprietary archiving formats, but InstallShield CAB files are the most common.
  • InstallShield CAB* files are recognized by their first 3 bytes: ISC.

For further guidance regarding supported and non-supported Cabinet files, please follow these instructions on auto$, before creating a support case or chatting with our support engineer.
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What CAB files are Supported/Non-Supported by MetaDefender’s Deep CDR?1. Microsoft Cabinet, Signature: MSCF2. InstallShield Cabinet, Signature: ISC