Cisco IOS XE Remote Access Probe Burst

name: Cisco IOS XE Remote Access Probe Burst
id: efb20922-17bc-4fb0-880c-be50cfc100dd
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 ping, SSH, and Telnet commands issued from Cisco IOS or NX-OS devices. The Salt Typhoon notes describe repeated SSH, Telnet-to-port-22, and ping activity across multiple IP addresses in a short time window.
data_source:
    - Cisco IOS Logs
search: |-
    `cisco_ios`
    facility IN ("AAA", "HA_EM")
    mnemonic IN ("AAA_ACCOUNTING_MESSAGE", "LOG")
    message_text IN ("*ssh *", "*telnet *", "*ping *")
    | 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, "")))
    | where match(command, "^(ssh|telnet|ping)\s+")
    | rex field=command "(?i)^(?:ssh(?:\s+-l\s+\S+)?|telnet|ping)\s+(?<target_ip>\d{1,3}(?:\.\d{1,3}){3})"
    | eval command_type=case(match(command, "^ssh\s+"), "ssh", match(command, "^telnet\s+"), "telnet", match(command, "^ping\s+"), "ping")
    | 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=10m
    | stats count as command_count
            min(_time) as firstTime
            max(_time) as lastTime
            dc(target_ip) as distinct_targets
            values(target_ip) as target_ips
            values(command_type) as command_types
            values(command) as commands
      by _time dest user src_ip
    | where command_count >= 8 OR distinct_targets >= 5
    | `security_content_ctime(firstTime)`
    | `security_content_ctime(lastTime)`
    | `cisco_ios_xe_remote_access_probe_burst_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".
    Command visibility requires AAA command accounting, archive/config logging for configuration commands, or EEM catchall logging.
known_false_positives: |
    Network reachability testing, migration validation, and troubleshooting can generate repeated ping, SSH, or Telnet commands.
references:
    - https://www.cisa.gov/news-events/cybersecurity-advisories/aa25-239a
    - https://blog.talosintelligence.com/salt-typhoon-analysis/
intermediate_findings:
    entities:
        - field: dest
          type: system
          score: 20
          message: User $user$ issued $command_count$ ping, SSH, or Telnet commands from Cisco device $dest$ across $distinct_targets$ targets.
threat_objects:
    - field: target_ips
      type: ip_address
    - field: commands
      type: command
analytic_story:
    - Salt Typhoon
asset_type: Network
mitre_attack_id:
    - T1018
    - T1021.004
    - T1046
product:
    - Splunk Enterprise
    - Splunk Enterprise Security
    - Splunk Cloud
category: application
security_domain: network