Detection rules › Elastic

Potential Reverse Shell via Powershell

Source
github.com/elastic/protections-artifacts

Identifies the execution of a PowerShell script that may allow remote commands execution via TCP, UDP or ICMP reverse shell.

MITRE ATT&CK coverage

Rule body

[rule]
description = """
Identifies the execution of a PowerShell script that may allow remote commands execution via TCP, UDP or ICMP reverse
shell.
"""
id = "a4a0537b-040e-4319-afce-a71ea547d45d"
license = "Elastic License v2"
name = "Potential Reverse Shell via Powershell"
os_list = ["windows"]
reference = ["https://github.com/samratashok/nishang/tree/master/Shells"]
version = "1.0.2"

query = '''
api where process.Ext.api.name == "AmsiScanBuffer" and
 (process.name in~ ("powershell.exe") or process.Ext.api.parameters.app_name == "PowerShell") and
  process.Ext.api.parameters.buffer : ("*Sockets.TCPClient(*", "*Sockets.UDPClient(*", "*Net.NetworkInformation.Ping*") and
  process.Ext.api.parameters.buffer : ("*while(*", "*while (*") and process.Ext.api.parameters.buffer : ("*.GetStream()*", "*.GetBytes(*") and
  process.Ext.api.parameters.buffer : ("*.Read(*", "*.Receive(*", "*.GetString(*") and process.Ext.api.parameters.buffer : ("*.Write(*", "*.Send(*")
'''

min_endpoint_version = "8.16.0"
[[actions]]
action = "kill_process"
field = "process.entity_id"
state = 0
tree = true

[[optional_actions]]
action = "rollback"
field = "process.entity_id"
state = 0

[[threat]]
framework = "MITRE ATT&CK"
[[threat.technique]]
id = "T1059"
name = "Command and Scripting Interpreter"
reference = "https://attack.mitre.org/techniques/T1059/"
[[threat.technique.subtechnique]]
id = "T1059.001"
name = "PowerShell"
reference = "https://attack.mitre.org/techniques/T1059/001/"



[threat.tactic]
id = "TA0002"
name = "Execution"
reference = "https://attack.mitre.org/tactics/TA0002/"
[[threat]]
framework = "MITRE ATT&CK"
[[threat.technique]]
id = "T1071"
name = "Application Layer Protocol"
reference = "https://attack.mitre.org/techniques/T1071/"


[threat.tactic]
id = "TA0011"
name = "Command and Control"
reference = "https://attack.mitre.org/tactics/TA0011/"

[internal]
min_endpoint_version = "8.16.0"

Stages and Predicates

Stage 1: api

api where process.Ext.api.name == "AmsiScanBuffer" and
 (process.name in~ ("powershell.exe") or process.Ext.api.parameters.app_name == "PowerShell") and
  process.Ext.api.parameters.buffer : ("*Sockets.TCPClient(*", "*Sockets.UDPClient(*", "*Net.NetworkInformation.Ping*") and
  process.Ext.api.parameters.buffer : ("*while(*", "*while (*") and process.Ext.api.parameters.buffer : ("*.GetStream()*", "*.GetBytes(*") and
  process.Ext.api.parameters.buffer : ("*.Read(*", "*.Receive(*", "*.GetString(*") and process.Ext.api.parameters.buffer : ("*.Write(*", "*.Send(*")

Indicators

These rows show field, operator, and value matches.

FieldKindValuesSearch
process.Ext.api.nameeq
  • AmsiScanBuffer corpus 16 (elastic 16)
field:"process.Ext.api.name" kind:eq value:"AmsiScanBuffer"
process.Ext.api.parameters.app_nameeq
  • PowerShell corpus 10 (elastic 10)
field:"process.Ext.api.parameters.app_name" kind:eq value:"PowerShell"
process.Ext.api.parameters.bufferwildcard
  • *.GetBytes(*
  • *.GetStream()*
  • *.GetString(*
  • *.Read(*
  • *.Receive(*
  • *.Send(*
  • *.Write(*
  • *Net.NetworkInformation.Ping*
  • *Sockets.TCPClient(*
  • *Sockets.UDPClient(*
  • *while (* corpus 2 (elastic 2)
  • *while(* corpus 2 (elastic 2)
field:"process.Ext.api.parameters.buffer" kind:wildcard
process.namein
  • powershell.exe corpus 184 (elastic 140, splunk 44)
field:"process_name" kind:in value:"powershell.exe"