PowerShell Suspicious Payload Encoded and Compressed
editPowerShell Suspicious Payload Encoded and Compressed
editIdentifies the use of .NET functionality for decompression and base64 decoding combined in PowerShell scripts, which malware and security tools heavily use to deobfuscate payloads and load them directly in memory to bypass defenses.
Rule type: query
Rule indices:
- winlogbeat-*
- logs-windows.*
Severity: medium
Risk score: 47
Runs every: 5 minutes
Searches indices from: now-9m (Date Math format, see also Additional look-back time
)
Maximum alerts per execution: 100
Tags:
- Elastic
- Host
- Windows
- Threat Detection
- Defense Evasion
Version: 3 (version history)
Added (Elastic Stack release): 8.0.0
Last modified (Elastic Stack release): 8.2.0
Rule authors: Elastic
Rule license: Elastic License v2
Potential false positives
editLegitimate PowerShell Scripts which makes use of compression and encoding.
Rule query
editevent.category:process and powershell.file.script_block_text : ( ( "System.IO.Compression.DeflateStream" or "System.IO.Compression.GzipStream" or "IO.Compression.DeflateStream" or "IO.Compression.GzipStream" ) and FromBase64String )
Threat mapping
editFramework: MITRE ATT&CKTM
-
Tactic:
- Name: Defense Evasion
- ID: TA0005
- Reference URL: https://attack.mitre.org/tactics/TA0005/
-
Technique:
- Name: Deobfuscate/Decode Files or Information
- ID: T1140
- Reference URL: https://attack.mitre.org/techniques/T1140/
-
Tactic:
- Name: Execution
- ID: TA0002
- Reference URL: https://attack.mitre.org/tactics/TA0002/
-
Technique:
- Name: Command and Scripting Interpreter
- ID: T1059
- Reference URL: https://attack.mitre.org/techniques/T1059/
Rule version history
edit- Version 3 (8.2.0 release)
-
-
Updated query, changed from:
event.category:process and powershell.file.script_block_text : ( (System.IO.Compression.DeflateStream or System.IO.Compression.GzipStream or IO.Compression.DeflateStream or IO.Compression.GzipStream) and FromBase64String )
-
- Version 2 (8.1.0 release)
-
- Formatting only