Invocation Of Crypto-Classes From The Cryptography PowerShell Namespace
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About the rule
Rule Type
Standard
Rule Description
Detects the invocation of PowerShell commands with references to classes from the System.Security.Cryptography namespace. The PowerShell namespace System.Security.Cryptography provides classes for on-the-fly encryption and decryption. These can be used for example in decrypting malicious payload for defense evasion.
Severity
Trouble
Rule Requirement
Criteria
Action1:
actionname = "Process started" AND (PROCESSNAME endswith "\powershell.exe,\pwsh.exe" OR ORIGINALFILENAME = "PowerShell.EXE,pwsh.dll") AND COMMANDLINE contains "System.Security.Cryptography." AND COMMANDLINE contains ".AesCryptoServiceProvider,.DESCryptoServiceProvider,.DSACryptoServiceProvider,.RC2CryptoServiceProvider,.Rijndael,.RSACryptoServiceProvider,.TripleDESCryptoServiceProvider"
select Action1.HOSTNAME,Action1.MESSAGE,Action1.COMMANDLINE,Action1.FILE_NAME,Action1.PROCESSNAME,Action1.USERNAME,Action1.PARENTPROCESSNAME,Action1.DOMAIN,Action1.ORIGINALFILENAME,Action1.PARENTPROCESSID,Action1.PROCESSID,Action1.PRODUCT_NAME,Action1.SECURITYID
Detection
Execution Mode
realtime
Log Sources
Windows
