Windows – How to open a .zip / .tar.* file attached in a .pdf file in Adobe Reader/Acrobat XI

Adobe now has an official fix for this problem.
Download Acrofix here.

Searching the internet for this specific error message gives me this result: https://helpx.adobe.com/acrobat/kb/error-adobe-acrobat-DC-cannot-open-the-file-attachment-settings-do-not-allow-this-file-type-to-be-opened-after-august-release.html

Which tells us that this is by design:

This is a designed behavior because the following office macro-enabled extensions have been blocked in August Release:

.xlsm, .xlsb, .xlm, .xltm, .xla, .xlam,.xll // Excel macro enabled extensions
.docm, .dotm, .docb // Word macro enabled extensions
.pptm, .potm, .ppam, .ppsm, .sldm // Power Point:
.accde, .accdr // access

This page suggests you can set Adobe Reader policy and settings via the Registry to possibly whitelist certain file types: https://www.adobe.com/devnet-docs/acrobatetk/tools/AppSec/attachments.html

Start by opening Edit > Preferences > Trust Manager and enable Allow opening of non-PDF attachments with external applications, if it is not already enabled.

Because the information in the first document I found suggests that these attachments are treated specially due to being particular security issues, you'll probably need to manually specify that Acrobat is allowed to open them using the information from the second link above.

The default application behavior for file types in the attachment list can be modified manually as needed. New file extensions can be added to the list, existing ones removed, and the behavior changed for file types already in the list.

Permissions settings are as follows:

1. User is warned that the file may be unsafe and is given two choices: open or permanently set the behavior to Prohibited.

2. User is warned that the file may be unsafe and is given three choices: open or permanently set the behavior to Allowed or Prohibited.

3. Always open this file type.

4. This file type does not open and a warning message appears.

Modifying the registry settings in HKLM requires administrator rights. To modify file attachments permissions:

On 64 bit machines, navigate to HKLM\SOFTWARE\WOW6432Node\Policies\Adobe\(product name)\(version)\FeatureLockdown\cDefaultLaunchAttachmentPerms.

Double click the tBuiltInPermList value.

Edit or add an extension and value in the format of .extension>:#. For example, zip:1. This is a simple, pipe-separated list (e.g. |doc|docx|dv|emf|). Refer to the actual preference values for a list of current settings.

Note

The ordering of the entries is irrelevant, but it is important that the list has no duplicate entries.

Attachment permissions example

version:1|.ade:3|.adp:3|.app:3|.arc:3|.arj:3|.asp:3|.bas:3|.bat:3|.bz:3|.bz2:3|.cab:3|.chm:3|.class:3|