signature-base/yara/gen_nopowershell.yar

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/*
Yara Rule Set
Author: YarGen Rule Generator
Date: 2016-05-21
Identifier: No PowerShell
*/
rule No_PowerShell {
meta:
description = "Detects an C# executable used to circumvent PowerShell detection - file nps.exe"
license = "https://creativecommons.org/licenses/by-nc/4.0/"
author = "Florian Roth"
reference = "https://github.com/Ben0xA/nps"
date = "2016-05-21"
score = 80
hash1 = "64f811b99eb4ae038c88c67ee0dc9b150445e68a2eb35ff1a0296533ae2edd71"
strings:
$s1 = "nps.exe -encodedcommand {base64_encoded_command}" fullword wide
$s2 = "c:\\Development\\ghps\\nps\\nps\\obj\\x86\\Release\\nps.pdb" fullword ascii
condition:
( uint16(0) == 0x5a4d and filesize < 40KB and ( 1 of ($s*) ) ) or ( all of them )
}