Cisco IOS XE Reconnaissance Command Activity
SPLUNK detection rule by Nasreddine Bencherchali · Apache-2.0
This analytic detects bursts of Cisco IOS or NX-OS discovery commands associated with Salt Typhoon tradecraft.
Adversaries who gain initial access to network infrastructure devices typically perform systematic reconnaissance to understand the device configuration, network topology, security policies, connected systems, and potential attack paths.
This reconnaissance phase involves executing multiple "show" commands to enumerate device details, running configurations, active connections, routing information, and VPN sessions.
name: Cisco IOS XE Reconnaissance Command Activity
id: 71ac5328-2364-40cf-8381-92b8dc531399
version: 1
creation_date: '2026-05-19'
modification_date: '2026-05-20'
author: Nasreddine Bencherchali
status: production
type: Anomaly
description: |
This analytic detects bursts of Cisco IOS or NX-OS discovery commands associated with Salt Typhoon tradecraft.
Adversaries who gain initial access to network infrastructure devices typically perform systematic reconnaissance to understand the device configuration, network topology, security policies, connected systems, and potential attack paths.
This reconnaissance phase involves executing multiple "show" commands to enumerate device details, running configurations, active connections, routing information, and VPN sessions.
data_source:
- Cisco IOS Logs
search: |-
`cisco_ios`
facility IN ("AAA", "HA_EM")
mnemonic IN ("AAA_ACCOUNTING_MESSAGE", "LOG")
message_text IN (
"*show running-config*",
"*show tacacs*",
"*show cdp neighbors*",
"*show file systems*",
"*dir bootflash:*",
"*show clock*",
"*show platform software status control-processor brief*",
"*terminal length 0*",
"*terminal width 0*"
)
| rex field=message_text "^\w+:(?<aaa_src>[^:@]+)(?:@[^:]*)?:(?<aaa_user>[^:]*):(?<aaa_command>.*?)(?:\s+\((?<aaa_result>SUCCESS|FAILURE)\))?$"
| rex field=message_text "^(?:[^:]+:\s+)?(?:catchall:\s+)?(?<eem_command>.+?)\s*$"
| eval command=lower(trim(coalesce(aaa_command, eem_command, "")))
| eval command_type=case(
like(command, "show running-config%"), "show_conf",
like(command, "show tacacs%"), "show_tacacs",
like(command, "show cdp neighbors detail%"), "show_cdp",
like(command, "show cdp neighbors%"), "show_cdp",
like(command, "show file systems%"), "show_file",
like(command, "dir bootflash:%"), "dir_bootflash",
like(command, "show clock%"), "show_clock",
like(command, "show platform software status control-processor brief%"), "show_platform",
like(command, "terminal length 0%"), "terminal",
like(command, "terminal width 0%"), "terminal",
true(), null())
| where isnotnull(command_type)
| eval user=coalesce(aaa_user, user, "unknown")
| eval src_ip=coalesce(aaa_src, src_ip, "unknown")
| eval dest=coalesce(host, dvc, dest, "unknown")
| bin _time span=5m
| stats count min(_time) as firstTime
max(_time) as lastTime
dc(command_type) as unique_recon_commands
values(command_type) as command_types
values(command) as commands
by _time dest user src_ip
| where unique_recon_commands >= 4
| `security_content_ctime(firstTime)`
| `security_content_ctime(lastTime)`
| `cisco_ios_xe_reconnaissance_command_activity_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".
On Nexus, local accounting can emit "%AAA-6-AAA_ACCOUNTING_MESSAGE".
On Catalyst, use TACACS+ command accounting or EEM catchall syslog for exec command visibility.
known_false_positives: |
Network audits and troubleshooting can produce similar command bursts. Tune the command list, threshold, and approved administrators for the environment.
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: User $user$ executed $unique_recon_commands$ Cisco reconnaissance command categories on $dest$.
threat_objects:
- field: commands
type: command
analytic_story:
- Salt Typhoon
asset_type: Network
mitre_attack_id:
- T1082
- T1016
- T1590
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:nexus:syslog
sourcetype: cisco:ios
test_type: unit
CIRCL