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Description

The following analytic identifies suspicious PowerShell command to allow inbound traffic inbound to a specific local port within the public profile. This technique was seen in some attacker want to have a remote access to a machine by allowing the traffic in firewall rule.

  • Type: TTP
  • Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
  • Datamodel: Endpoint
  • Last Updated: 2021-05-19
  • Author: Teoderick Contreras, Splunk
  • ID: a5d85486-b89c-11eb-8267-acde48001122

Annotations

ATT&CK
ID Technique Tactic
T1021.001 Remote Desktop Protocol Lateral Movement
T1021 Remote Services Lateral Movement
Kill Chain Phase
  • Exploitation
NIST
CIS20
CVE
1
2
3
4
5
`powershell` EventCode=4104 Message = "*firewall*" Message = "*Inbound*" Message = "*Allow*"  Message = "*-LocalPort*" 
| stats count min(_time) as firstTime max(_time) as lastTime by EventCode Message ComputerName User 
| `security_content_ctime(firstTime)` 
| `security_content_ctime(lastTime)` 
| `allow_inbound_traffic_in_firewall_rule_filter`

Macros

The SPL above uses the following Macros:

Note that allow_inbound_traffic_in_firewall_rule_filter is a empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.

Required field

  • _time
  • EventCode
  • Message
  • ComputerName
  • User

How To Implement

To successfully implement this search, you need to be ingesting logs with the powershell logs from your endpoints. make sure you enable needed registry to monitor this event.

Known False Positives

administrator may allow inbound traffic in certain network or machine.

Associated Analytic story

RBA

Risk Score Impact Confidence Message
3.0 10 30 Suspicious firewall modification detected on endpoint $ComputerName$ by user $user$.

Reference

Test Dataset

Replay any dataset to Splunk Enterprise by using our replay.py tool or the UI. Alternatively you can replay a dataset into a Splunk Attack Range

source | version: 1