Network Sniffing - Linux

Status: test
Severity: low
Log source: product linux, service auditd
Author: Timur Zinniatullin, oscd.community
Source: github.com/SigmaHQ/sigma

Network sniffing refers to using the network interface on a system to monitor or capture information sent over a wired or wireless connection. An adversary may place a network interface into promiscuous mode to passively access data in transit over the network, or use span ports to capture a larger amount of data.

Known false positives

Legitimate administrator or user uses network sniffing tool for legitimate reasons.

MITRE ATT&CK coverage

Tactic	Techniques
Credential Access	`T1040` Network Sniffing
Discovery	`T1040` Network Sniffing

Telemetry coverage

Platform	Record / event type
Linux	auditd EXECVE record: Arguments supplied to the execve system call

Rule body

title: Network Sniffing - Linux
id: f4d3748a-65d1-4806-bd23-e25728081d01
status: test
description: |
  Network sniffing refers to using the network interface on a system to monitor or capture information sent over a wired or wireless connection.
  An adversary may place a network interface into promiscuous mode to passively access data in transit over the network, or use span ports to capture a larger amount of data.
references:
    - https://github.com/redcanaryco/atomic-red-team/blob/f339e7da7d05f6057fdfcdd3742bfcf365fee2a9/atomics/T1040/T1040.md
author: Timur Zinniatullin, oscd.community
date: 2019-10-21
modified: 2022-12-18
tags:
    - attack.credential-access
    - attack.discovery
    - attack.t1040
logsource:
    product: linux
    service: auditd
detection:
    selection_1:
        type: 'execve'
        a0: 'tcpdump'
        a1: '-c'
        a3|contains: '-i'
    selection_2:
        type: 'execve'
        a0: 'tshark'
        a1: '-c'
        a3: '-i'
    condition: 1 of selection_*
falsepositives:
    - Legitimate administrator or user uses network sniffing tool for legitimate reasons.
level: low

Stages and Predicates

Stage 0: `condition`

1 of selection_*

Stage 1: `selection_1`

selection_1:
    type: 'execve'
    a0: 'tcpdump'
    a1: '-c'
    a3|contains: '-i'

Stage 2: `selection_2`

selection_2:
    type: 'execve'
    a0: 'tshark'
    a1: '-c'
    a3: '-i'

Indicators

These rows show field, operator, and value matches.

Field	Kind	Values	Search
`a0`	eq	`tcpdump` `tshark`	`field:"a0" kind:eq`
`a1`	eq	`-c`	`field:"a1" kind:eq value:"-c"`
`a3`	eq	`-i`	`field:"a3" kind:eq value:"-i"`
`a3`	match	`-i`	`field:"a3" kind:match value:"-i"`
`type`	eq	`execve`	`field:"type" kind:eq value:"execve"`