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Florian edited this page Jul 30, 2020 · 5 revisions

Disabled Features

Generic Windows Features

  • Disable Windows Script Host. Windows Script Host allows the execution of VBScript and JavaScript files on Windows operating systems. This is very commonly used by regular malware (such as ransomware) as well as targeted malware.

  • Disabling AutoRun and AutoPlay. Disables AutoRun / AutoPlay for all devices. This prevents applications from automatically executing when you plug a USB stick into your computer.

  • Disables powershell.exe and powershell_ise.exe execution via Windows Explorer. This prevents the use of PowerShell by malicious code trying to infect the system. You will not be able to open PowerShell directly anymore.

  • Disables cmd.exe execution via Windows Explorer (optional). You will not be able to use the cmd terminal and it should prevent malicious code trying to infect the system by using cmd.exe to e.g. start powershell.exe. This setting is optional because cmd.exe is used quite often by users and applications. This must therefore be enabled manually in the expert settings section.

  • Sets User Account Control (UAC) to always ask for permission (even on configuration changes only) and to use "secure desktop".

  • Disable file extensions mainly used for malicious purposes. Disables the ".hta", ".js", ".JSE", ".WSH", ".WSF", ".scf", ".scr", ".vbs", ".vbe" and ".pif" file extensions for the current user (and for system wide defaults, which is only relevant for newly created users).

  • Shows file extensions and hidden files in explorer. This is very useful to detect files pretending to be another file type (e.g. an exe file named like iAmSimulatingToBeAPdf.pdf.exe)

  • Activates additional LSA Protection (Optional / Expert Setting): With this setting enabled Windows provides additional protection for the LSA processes to prevent reading memory from and code injection by non-protected processes. This provides added security against reading of credentials by malicious processes.

  • Windows Defender Attack Surface Reduction (ASR) rules. Enables various remediations using ASR rules starting with Windows 10 / 1709. To be effective this needs the following prerequisites:

    • Windows 10 version >= 1709,
    • You are using Windows Defender Antivirus as the sole antivirus protection app,
    • Real-time protection is enabled in Windows Defender.
    • Cloud protection is enabled in Windows Defender (only needed for some of the ASR rules)

    The following ASR rules are implemented:

    • Block executable content from email client and webmail
    • Block Office applications from creating child processes
    • Block Office applications from creating executable content & from injecting code into other processes
    • Block JavaScript or VBScript from launching downloaded executable content
    • Block execution of potentially obfuscated scripts
    • Block Win32 API calls from Office macros
    • Block untrusted and unsigned processes that run from USB
    • Use advanced protection against ransomware
    • Block process creations originating from PSExec and WMI commands
    • Block Office communication application from creating child processes
    • Block Adobe Reader from creating child processes
    • Block persistence through WMI event subscription
    • Block credential stealing from the Windows local security authority subsystem

    The following ASR rules are not implemented right now:

    • Block executable files from running unless they meet a prevalence, age, or trusted list criterion (due to too much impact, e.g. hardentools might get blocked)

Microsoft Office

  • Disable Macros. Macros are at times used by Microsoft Office users to script and automate certain activities, especially calculations with Microsoft Excel. However, macros are currently a security plague, and they are widely used as a vehicle for compromise. With Hardentools, macros are disabled and the "Enable this Content" notification is disabled too, to prevent users from being tricked.

  • Disable OLE object execution. Microsoft Office applications are able to embed so called "OLE objects" and execute them, at times also automatically (for example through PowerPoint animations). Windows executables, such as spyware, can also be embedded and executed as an object. This is also a security disaster which we observed used time and time again, particularly in attacks against activists in repressed regions. Hardentools entirely disables this functionality.

  • Disabling ActiveX. Disables ActiveX Controls for all Office applications. ActiveX controls can provide additional functionality in documents and are mostly used in enterprise environments. The impact of this setting is that ActiveX controls do not initialize and you are not notified that the ActiveX controls are disabled. Note: This doesn't disable ActiveX in Internet Explorer.

  • Disable DDE and Excel Links. Disables DDE for Word, Excel and Outlook. The DDE protocol allows to send messages between applications to share data. This is an attack vector if the user opens a malicious document. Side effects are:

    • If there are links to other office documents (to update data in a excel sheet for instance) this data is not updated automatically anymore. If you are using such kinds of documents you might have to disable this harden setting.

    • Every Excel document is opened in a separate Excel instance if opened using Windows explorer. This might also have impact on sharing data between the documents and consume more memory.

Acrobat Reader

  • Disable JavaScript in PDF documents. Acrobat Reader allows to execute JavaScript code from within PDF documents. This is widely abused for exploitation and malicious activity.

  • Disable execution of objects embedded in PDF documents. Acrobat Reader also allows to execute embedded objects by opening them. This would normally raise a security alert, but given that legitimate uses of this are rare and limited, Hardentools disables this.

  • Switch on the Protected Mode. When protected mode is enabled, Acrobat Reader assumes all PDFs are potentially malicious and confines any processing they invoke to a sandbox so that malicious PDF files can't infect the computer. (This setting is enabled by default in current Acrobat Reader versions.)

  • Switch on Protected View for all files from untrusted sources. In the Protected View mode, most features are disabled to prevent malicious PDF files to do harm. You can view the PDF, but not do much else. A yellow bar displays on top of the Reader window. Click Enable All Features to exit the Protected View. but do that with caution and only for files you are really sure to originate from a trusted source.

  • Switch on Enhanced Security. This setting disallows PDF files to fetch data from untrusted locations. (This setting is enabled by default in current Acrobat Reader versions.)

References

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