Cisco IOS XE Tunnel Interface Configuration

SPLUNK detection rule by Nasreddine Bencherchali · Apache-2.0

This analytic detects creation of a Cisco IOS-XE tunnel interface with tunnel source, tunnel destination, and an IP address in the 10.10.12.0 network. The Salt Typhoon notes identify this tunnel configuration pattern as suspicious.

name: Cisco IOS XE Tunnel Interface Configuration
id: 8654314d-8e4d-4971-9f35-b9d477bf668e
version: 1
creation_date: '2026-05-19'
modification_date: '2026-05-20'
author: Nasreddine Bencherchali
status: production
type: Anomaly
description: |
    This analytic detects creation of a Cisco IOS-XE tunnel interface with tunnel source, tunnel destination, and an IP address in the 10.10.12.0 network. The Salt Typhoon notes identify this tunnel configuration pattern as suspicious.
data_source:
    - Cisco IOS Logs
search: |-
    `cisco_ios`
    facility IN ("HA_EM", "PARSER")
    mnemonic IN ("LOG", "CFGLOG_LOGGEDCMD")
    message_text IN ("*interface Tunnel*", "*tunnel source*", "*tunnel destination*", "*ip address 10.10.12.*")
    | rex field=message_text "^(?:[^:]+:\s+)?(?:catchall:\s+)?(?<eem_command>.+?)\s*$"
    | rex field=message_text "<enteredCommand><cli>(?<parser_command>.*?)</cli>"
    | rex field=message_text "<user>(?<parser_user>[^<]+)</user>"
    | rex field=message_text "<srcIP>(?<parser_src_ip>[^<]+)</srcIP>"
    | eval command=lower(trim(coalesce(parser_command, eem_command, "")))
    | eval event_type=case(
        match(command, "^interface\s+tunnel"), "interface_tunnel",
        match(command, "^tunnel\s+source"), "tunnel_source",
        match(command, "^tunnel\s+destination"), "tunnel_destination",
        match(command, "^ip\s+address\s+10\.10\.12\."), "tunnel_ip_address",
        true(), null())
    | where isnotnull(event_type)
    | eval user=coalesce(parser_user, user, "unknown")
    | eval src_ip=coalesce(parser_src_ip, src_ip, "unknown")
    | eval dest=coalesce(host, dvc, dest, "unknown")
    | bin _time span=15m
    | stats count min(_time) as firstTime
                  max(_time) as lastTime
                  values(event_type) as event_types
                  values(user) as user
                  values(src_ip) as src_ip
                  values(command) as commands
      by _time dest
    | where mvfind(event_types, "interface_tunnel") >= 0
            AND
            mvfind(event_types, "tunnel_source") >= 0
            AND
            mvfind(event_types, "tunnel_destination") >= 0
            AND
            mvfind(event_types, "tunnel_ip_address") >= 0
    | `security_content_ctime(firstTime)`
    | `security_content_ctime(lastTime)`
    | `cisco_ios_xe_tunnel_interface_configuration_filter`
how_to_implement: |
    Use the Cisco Catalyst Add-on for Splunk (https://splunkbase.splunk.com/app/7538) to Ingest Cisco IOS-XE syslog with sourcetype "cisco:ios" and enable archive/config command logging.
known_false_positives: |
    No false positives have been identified at this time.
references:
    - https://www.cisa.gov/news-events/cybersecurity-advisories/aa25-239a
    - https://blog.talosintelligence.com/salt-typhoon-analysis/
drilldown_searches:
    - name: View the detection results for - "$dest$"
      search: '%original_detection_search% | search  dest = "$dest$"'
      earliest_offset: $info_min_time$
      latest_offset: $info_max_time$
    - name: View risk events for the last 7 days for - "$dest$"
      search: '| from datamodel Risk.All_Risk | search normalized_risk_object IN ("$dest$") | 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: dest
          type: system
          score: 20
          message: Cisco IOS-XE tunnel interface configuration matching Salt Typhoon notes was observed on $dest$ by $user$.
threat_objects:
    - field: commands
      type: command
analytic_story:
    - Salt Typhoon
asset_type: Network
mitre_attack_id:
    - T1572
    - T1090
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/emerging_threats/SaltTyphoon/salttyphoon_cisco.log
          source: ctb:catalyst:syslog
          sourcetype: cisco:ios
      test_type: unit

[[ currentRule.title && currentRule.title.length > 60 ? currentRule.title.slice(0, 60) + '…' : currentRule.title ]]

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Executable code, not a declarative rule

This submission is arbitrary [[ currentRule.format ? currentRule.format.toUpperCase() : '' ]] code, not a declarative detection rule — review it as you would any script before running it, and note that it cannot be safely aggregated or auto-executed alongside YARA/Sigma/Suricata/CRS rules.

Rejected pattern present

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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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