Cisco ASA - Packet Capture Activity

SPLUNK detection rule by Nasreddine Bencherchali, Splunk · Apache-2.0

This analytic detects execution of packet capture commands on Cisco ASA devices via CLI or ASDM. Adversaries may abuse the built-in packet capture functionality to perform network sniffing, intercept credentials transmitted over the network, capture sensitive data in transit, or gather intelligence about network traffic patterns and internal communications. Packet captures can reveal usernames, passwords, session tokens, and confidential business data. The detection monitors for command execution events (message ID 111008 or 111010) containing "capture" commands, which are used to initiate packet capture sessions on specific interfaces or for specific traffic patterns on the ASA device. Investigate unauthorized packet capture activities, especially captures targeting sensitive interfaces (internal network segments, DMZ), captures configured to capture large volumes of traffic, captures with suspicious filter criteria, captures initiated by non-administrative accounts, or captures during unusual hours.

name: Cisco ASA - Packet Capture Activity
id: 7e9c3f8a-4b2d-4c5e-9a1f-6d8e5b3c2a9f
version: 5
creation_date: '2025-11-21'
modification_date: '2026-05-13'
author: Nasreddine Bencherchali, Splunk
status: production
type: Anomaly
description: |
    This analytic detects execution of packet capture commands on Cisco ASA devices via CLI or ASDM.
    Adversaries may abuse the built-in packet capture functionality to perform network sniffing, intercept credentials transmitted over the network, capture sensitive data in transit, or gather intelligence about network traffic patterns and internal communications. Packet captures can reveal usernames, passwords, session tokens, and confidential business data.
    The detection monitors for command execution events (message ID 111008 or 111010) containing "capture" commands, which are used to initiate packet capture sessions on specific interfaces or for specific traffic patterns on the ASA device.
    Investigate unauthorized packet capture activities, especially captures targeting sensitive interfaces (internal network segments, DMZ), captures configured to capture large volumes of traffic, captures with suspicious filter criteria, captures initiated by non-administrative accounts, or captures during unusual hours.
data_source:
    - Cisco ASA Logs
search: |
    `cisco_asa`
    message_id IN (111008, 111010)
    command IN ("capture *")
    | fillnull
    | stats count
            earliest(_time) as firstTime
            latest(_time) as lastTime
            values(user) as user
            values(action) as action
            values(message_id) as message_id
            values(command) as command
            values(src_ip) as src_ip
            values(process_name) as process_name
      by host
    | `security_content_ctime(firstTime)`
    | `security_content_ctime(lastTime)`
    | `cisco_asa___packet_capture_activity_filter`
how_to_implement: |
    This search requires Cisco ASA syslog data to be ingested into Splunk via the Cisco Security Cloud TA.
    To ensure this detection works effectively, configure your ASA and FTD devices to generate and forward message ID 111008 and 111010.
    If your logging level is set to 'notifications' or higher, these messages should already be included, else we recommend setting an event list that keeps the severity level you are using and adding the message IDs 111008 and 111010.
    You can find specific instructions on how to set this up here : https://www.cisco.com/c/en/us/support/docs/security/pix-500-series-security-appliances/63884-config-asa-00.html.
    You can also change the severity level of the above message id's to the syslog level you have currently enabled using the logging message syslog_id level severity_level command in global configuration mode. For more information, see Change the Severity Level of a Syslog Message : https://www.cisco.com/c/en/us/td/docs/security/asa/asa922/configuration/general/asa-922-general-config/monitor-syslog.html#ID-2121-000006da
known_false_positives: |
    Admins use packet captures for troubleshooting, performance monitoring, or security investigations. Verify against change management. Filter known admin accounts during maintenance windows.
references:
    - https://www.cisco.com/c/en/us/td/docs/security/asa/asa-cli-reference/A-H/asa-command-ref-A-H/ca-cld-commands.html
    - https://www.cisco.com/c/en/us/support/docs/security/asa-5500-x-series-next-generation-firewalls/118097-configure-asa-00.html
    - https://www.ncsc.gov.uk/static-assets/documents/malware-analysis-reports/RayInitiator-LINE-VIPER/ncsc-mar-rayinitiator-line-viper.pdf
drilldown_searches:
    - name: View the detection results for $host$
      search: '%original_detection_search% | search  host = $host$'
      earliest_offset: $info_min_time$
      latest_offset: $info_max_time$
    - name: View risk events for the last 7 days for $host$
      search: '| from datamodel Risk.All_Risk | search normalized_risk_object IN ($host$) | stats count min(_time) as firstTime max(_time) as lastTime values(search_name) as "Search Name" values(risk_message) as "Risk Message" values(analyticstories) as "Analytic Stories" values(annotations._all) as "Annotations" values(annotations.mitre_attack.mitre_tactic) as "ATT&CK Tactics" by normalized_risk_object | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)`'
      earliest_offset: 7d
      latest_offset: "0"
intermediate_findings:
    entities:
        - field: host
          type: system
          score: 20
          message: User $user$ executed packet capture command $command$ on Cisco ASA host $host$, potentially for network sniffing activity.
        - field: user
          type: user
          score: 20
          message: User $user$ executed packet capture command $command$ on Cisco ASA host $host$, potentially for network sniffing activity.
threat_objects:
    - field: command
      type: process
analytic_story:
    - Suspicious Cisco Adaptive Security Appliance Activity
    - ArcaneDoor
asset_type: Network
mitre_attack_id:
    - T1040
    - T1557
product:
    - Splunk Enterprise
    - Splunk Enterprise Security
    - Splunk Cloud
category: application
security_domain: network
tests:
    - name: True Positive Test
      attack_data:
        - data: https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/cisco_asa/generic/cisco_asa_generic_logs.log
          source: not_applicable
          sourcetype: cisco:asa
      test_type: unit

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4d63ee16-3156-412a-b11d-43e6032f79ab

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Format & documentation suggestions

Not a security issue — this rule is valid and was accepted as-is. These are optional fields/conventions its own format recommends, mainly affecting its quality score and how well it documents itself for other reviewers.

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