Adversaries may use LAN sniffing to capture sensitive data transmitted over the network, indicating potential data exfiltration or reconnaissance. SOC teams should proactively hunt for this behavior in Azure Sentinel to identify and mitigate early-stage network-based threats before they escalate.
YARA Rule
rule sniff_lan {
meta:
author = "x0r"
description = "Sniff Lan network traffic"
version = "0.1"
strings:
$f1 = "packet.dll" nocase
$f2 = "npf.sys" nocase
$f3 = "wpcap.dll" nocase
$f4 = "winpcap.dll" nocase
condition:
any of them
}
This YARA rule can be deployed in the following contexts:
This rule contains 4 string patterns in its detection logic.
Scenario: Network traffic generated by a scheduled system backup using Veeam Backup & Replication
Filter/Exclusion: Exclude traffic from the Veeam backup server IP or port 9000 (used by Veeam for backup data transfer).
Scenario: Regular Ansible playbook execution that initiates SSH-based configuration pushes to multiple hosts
Filter/Exclusion: Exclude SSH traffic originating from Ansible control nodes or traffic to known Ansible-managed hosts.
Scenario: Logstash or Fluentd instances sending logs over TCP to a centralized logging server (e.g., Elasticsearch)
Filter/Exclusion: Exclude traffic to the logging server’s known IP or port (e.g., 5044 for Fluentd over TCP).
Scenario: PowerShell remoting (PSRemoting) used by administrators for routine system management tasks
Filter/Exclusion: Exclude traffic from known admin workstations or traffic using the PowerShell remoting port (5985 or 5986).
Scenario: DNS queries generated by internal DNS resolvers or Microsoft Intune policy updates
Filter/Exclusion: Exclude traffic to internal DNS servers or traffic from known Intune update endpoints.