Dark Reading is part of the Informa Tech Division of Informa PLC

This site is operated by a business or businesses owned by Informa PLC and all copyright resides with them.Informa PLC's registered office is 5 Howick Place, London SW1P 1WG. Registered in England and Wales. Number 8860726.

Network Security

12:30 PM
Larry Loeb
Larry Loeb
Larry Loeb

MSFT Updates Outlook Ban List for Downloads

Microsoft did some Outlook tweaking recently. They realized that the list of the file extensions that the program should refuse to download needed some updating.

Microsoft did some Outlook tweaking recently. They realized that the list of the file extensions that the program should refuse to download needed some updating.

Now, there will be consequences from this. For example, an enterprise (especially) has to make sure that the OwaMailboxPolicy objects changes are handled correctly for each user should they want enterprise-wide download exclusion.

In any case, MSFT says that the newly blocked file types are rarely used, so most organizations will not be affected by the change. However, if your users are using previously approved OMPs while sending and receiving the affected attachments, MSFT says that they will no longer will able to download them.

But, there is a way around this. If you want a particular file type to be allowed for a user, you can add that file type to the AllowedFileTypes property of your users' OMP objects. A file extension will not be added to a user's BlockedFileTypes list if that extension is already present in the AllowedFileTypes list. \r\nThe results of the list twiddling this time around is fairly long.\r\n From the Python scripting language, we find some obsolete file types, including ".py", ".pyc", ".pyo", ".pyw", ".pyz", ".pyzw."\r\nThe PowerShell scripting language -- an enabler of much filleless malware coding -- also gets trimmed. The ".ps1", ".ps1xml", ".ps2", ".ps2xml", ".psc1", ".psc2", ".psd1", ".psdm1", ".cdxml" and ".pssc" extensions are on the darklist.

The ".appref-ms" extension used by Windows ClickOnce gets hit as does the Microsoft Data Access Components (MDAC) extension ".udl."\r\nWindows sandbox gives up ".wsb" to the effort.

Digital certificates aren’t forgotten in the hullabaloo. The ".cer", ".crt" and ".der" extensions used by some are now gone.

The ".jar" and ".jnlp" extensions to be cut are used by the Java programming language quite extensively. Java is so powerful that allowing it unrestrained program access could prove seriously problematical from a security standpoint. Yet, there may be libraries in use by production code which assume they will be able to get to files containing that extension. That's a potential quagmire for an enterprise, especially if it relies on open sourced software.

From the Department of "You're Too Lame to Patch, So We Did It for You" came some extensions that MSFT explained this way. "While the associated vulnerabilities have been patched (for years, in most cases)," they said in the advisory, "they are being blocked for the benefit of organizations that might still have older versions of the application software in use." Lame-o.

The list of the miscellaneous ones is :".appcontent-ms", ".settingcontent-ms", ".cnt", ".hpj", ".website", ".webpnp", ".mcf", ".printerexport", ".pl", ".theme", ".vbp", ".xbap", ".xll", ".xnk", ".msu", ".diagcab" and ".grp".\r\n

— Larry Loeb has written for many of the last century's major "dead tree" computer magazines, having been, among other things, a consulting editor for BYTE magazine and senior editor for the launch of WebWeek.

Comment  | 
Print  | 
More Insights
Newest First  |  Oldest First  |  Threaded View
Manchester United Suffers Cyberattack
Dark Reading Staff 11/23/2020
As 'Anywhere Work' Evolves, Security Will Be Key Challenge
Robert Lemos, Contributing Writer,  11/23/2020
Cloud Security Startup Lightspin Emerges From Stealth
Kelly Sheridan, Staff Editor, Dark Reading,  11/24/2020
Register for Dark Reading Newsletters
White Papers
Cartoon Contest
Write a Caption, Win an Amazon Gift Card! Click Here
Latest Comment: This comment is waiting for review by our moderators.
Current Issue
2021 Top Enterprise IT Trends
We've identified the key trends that are poised to impact the IT landscape in 2021. Find out why they're important and how they will affect you today!
Flash Poll
Twitter Feed
Dark Reading - Bug Report
Bug Report
Enterprise Vulnerabilities
From DHS/US-CERT's National Vulnerability Database
PUBLISHED: 2020-11-28
In Eclipse Jetty version 9.4.0.RC0 to 9.4.34.v20201102, 10.0.0.alpha0 to 10.0.0.beta2, and 11.0.0.alpha0 to 11.0.0.beta2, if GZIP request body inflation is enabled and requests from different clients are multiplexed onto a single connection, and if an attacker can send a request with a body that is ...
PUBLISHED: 2020-11-27
blosc2.c in Blosc C-Blosc2 through 2.0.0.beta.5 has a heap-based buffer overflow when there is a lack of space to write compressed data.
PUBLISHED: 2020-11-27
npm package systeminformation before version 4.30.5 is vulnerable to Prototype Pollution leading to Command Injection. The issue was fixed with a rewrite of shell sanitations to avoid prototyper pollution problems. The issue is fixed in version 4.30.5. If you cannot upgrade, be sure to check or sani...
PUBLISHED: 2020-11-27
In Crafter CMS Crafter Studio 3.0.1 an unauthenticated attacker is able to inject malicious JavaScript code resulting in a stored/blind XSS in the admin panel.
PUBLISHED: 2020-11-27
In Crafter CMS Crafter Studio 3.0.1 an unauthenticated attacker is able to create a site with specially crafted XML that allows the retrieval of OS files out-of-band.