Threat Huntmediumtest
Invocation Of Crypto-Classes From The "Cryptography" PowerShell Namespace
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.
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Launch
Hunting Hypothesis
Log Source
WindowsProcess Creation
ProductWindows← raw: windows
CategoryProcess Creation← raw: process_creation
Events generated when a new process is spawned on the system. Covers command-line arguments, parent/child relationships, and process metadata.
Detection Logic
Detection Logic3 selectors
detection:
selection_img:
- Image|endswith:
- '\powershell.exe'
- '\pwsh.exe'
- OriginalFileName:
- 'PowerShell.EXE'
- 'pwsh.dll'
selection_cmdlet_namespace:
CommandLine|contains: 'System.Security.Cryptography.'
selection_cmdlet_classes:
CommandLine|contains:
- '.AesCryptoServiceProvider'
- '.DESCryptoServiceProvider'
- '.DSACryptoServiceProvider'
- '.RC2CryptoServiceProvider'
- '.Rijndael'
- '.RSACryptoServiceProvider'
- '.TripleDESCryptoServiceProvider'
condition: all of selection_*False Positives
Classes are legitimately used, but less so when e.g. parents with low prevalence or decryption of content in temporary folders.
MITRE ATT&CK
Sub-techniques
Other
detection.threat-hunting
Rule Metadata
Rule ID
ad856965-f44d-42a8-945e-bbf7bd03d05a
Status
test
Level
medium
Type
Threat Hunt
Created
Fri Dec 01
Path
rules-threat-hunting/windows/process_creation/proc_creation_win_powershell_crypto_namespace.yml
Raw Tags
attack.defense-evasionattack.executionattack.t1059.001attack.t1027.010detection.threat-hunting