Linux: Detect execution of tcpdump or tshark with interface (-i) capture option
Alerts on tcpdump or tshark executions on Linux where an interface flag is present, consistent with network sniffing.
- Product
- linux
- Service
- auditd
- Author
- Timur Zinniatullin, oscd.community (SigmaHQ), DRL 1.1
- Published
- 2019-10-21
- Updated
- 2026-07-31
ATT&CK techniques
Cred Access → DiscoveryRecon
Resource Dev
Initial Access
Execution
Persistence
Priv Esc
Defense Evasion
Cred Access
Discovery
Lateral Movement
Collection
C2
Exfiltration
Impact
What it detects
This rule flags processes where tcpdump or tshark are executed with command-line arguments indicating packet capture on a specified network interface (-i) and limiting captures (-c). This behavior matters because network sniffing can be used to passively collect information in transit or increase visibility into network traffic. Telemetry relies on Linux auditd records that capture execve command-line details for these tools.
Reporting behind it
Changelog
v3- v3Candidate ingested via manual entry.2026-07-31
- v2Candidate ingested via manual entry.2026-07-31
- v1No changelog recorded for this version.2026-07-30
Detection content is published as a reviewed draft. Tune thresholds and exclusions against your own telemetry before enabling this rule for alerting.
title: "Linux: Detect execution of tcpdump or tshark with interface (-i) capture option"
id: 5036dedf-f8a5-4caf-99f9-90f6fbf94ce8
status: test
description: This rule flags processes where tcpdump or tshark are executed with command-line arguments indicating packet capture on a specified network interface (-i) and limiting captures (-c). This behavior matters because network sniffing can be used to passively collect information in transit or increase visibility into network traffic. Telemetry relies on Linux auditd records that capture execve command-line details for these tools.
references:
- https://github.com/redcanaryco/atomic-red-team/blob/f339e7da7d05f6057fdfcdd3742bfcf365fee2a9/atomics/T1040/T1040.md
- https://github.com/SigmaHQ/sigma/blob/master/rules/linux/auditd/execve/lnx_auditd_network_sniffing.yml
author: Timur Zinniatullin, oscd.community, Huntrule Team
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
license: DRL-1.1
related:
- id: f4d3748a-65d1-4806-bd23-e25728081d01
type: derived