Detect Network Device CLI in Elastic Security
Adversaries may abuse scripting or built-in command line interpreters (CLI) on network devices to execute malicious commands and payloads. The CLI is the primary means through which users and administrators interact with network devices to view system information, modify device operations, or perform diagnostic and administrative functions. CLIs typically contain various permission levels. Adversaries can use the network CLI to change how devices behave, manipulate traffic flows to intercept data, modify startup configuration, load malicious firmware, or disable security features. The ArcaneDoor campaign (Line Dancer malware) demonstrated sophisticated CLI abuse on Cisco ASA devices.
MITRE ATT&CK
- Tactic
- Execution
- Technique
- T1059 Command and Scripting Interpreter
- Sub-technique
- T1059.008 Network Device CLI
- Canonical reference
- https://attack.mitre.org/techniques/T1059/008/
Elastic Detection Query
any where (
event.dataset : ("network.cisco_ios", "network.cisco_asa", "network.juniper_junos", "network.cisco_nxos") or
tags : ("cisco", "juniper", "network-device", "network-syslog") or
log.syslog.facility.name : ("local6", "local7")
) and (
message : "*configure terminal*" or
message : "*config t*" or
message : "*copy running-config*" or
message : "*copy startup-config*" or
message : "*no logging*" or
message : "*no ip access-list*" or
message : "*no service password-encryption*" or
message : "*access-list permit any any*" or
message : "*boot system*" or
message : "*archive download-sw*" or
message : "*copy tftp:*" or
message : "*copy ftp:*" or
message : "*username*privilege 15*" or
message : "*enable secret*" or
message : "*transport input all*" or
message : "*snmp-server community*" or
message : "*crypto key generate*" or
message : "*line vty*"
)Detects suspicious network device CLI commands associated with MITRE ATT&CK T1059.008. Monitors syslog ingested from Cisco IOS/ASA/NX-OS and Juniper JunOS devices for commands indicative of configuration tampering, security control disabling, firmware modification, and privilege escalation. Covers ArcaneDoor/Line Dancer-style CLI abuse patterns.
Data Sources
Required Tables
False Positives & Tuning
- Scheduled maintenance windows where administrators perform planned configuration changes such as ACL updates, route additions, or software upgrades — correlate with approved change tickets
- Automated network configuration management tools (Ansible, NAPALM, Cisco DNA Center, Netmiko scripts) that regularly push configs and generate CLI command syslog entries during authorized automation runs
- Routine firmware upgrade cycles where 'boot system' and 'copy tftp: flash:' commands are expected during patching windows — filter by maintenance calendar or approved change window time ranges
- Network monitoring platforms that use SNMP community string changes during scheduled credential rotation ('snmp-server community' commands)
- Security hardening scripts that add access-list entries or modify logging configurations as part of baseline enforcement workflows
Other platforms for T1059.008
Testing Methodology
Validate this detection against 3 adversary techniques from Atomic Red Team. Each test below lists the behaviour to exercise and the telemetry you should expect to see. Executable commands and cleanup steps are available with Pro.
- Test 1Cisco IOS Configuration Change Simulation
Expected signal: Syslog message with facility local7 and the CONFIG_I message tag. If forwarded to SIEM, this appears as a network device configuration change event.
- Test 2Network Device Security Disable Simulation
Expected signal: Syslog message with facility local7 containing 'no logging'. This simulates the alert trigger without requiring access to actual network equipment.
- Test 3Network Device Firmware Change Simulation
Expected signal: Syslog message with facility local7 containing 'copy tftp: flash:' firmware download pattern.
References (5)
- https://attack.mitre.org/techniques/T1059/008/
- https://blogs.cisco.com/security/evolution-of-attacks-on-cisco-ios-devices
- https://tools.cisco.com/security/center/resources/integrity_assurance.html#23
- https://blog.talosintelligence.com/arcanedoor-new-espionage-focused-campaign-found-targeting-perimeter-network-devices/
- https://www.mandiant.com/resources/blog/synful-knock-cisco
Unlock Pro Content
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