Detection: Cisco IOS XE Tunnel Interface Configuration

Updated Date: 2026-05-20 ID: 8654314d-8e4d-4971-9f35-b9d477bf668e Author: Nasreddine Bencherchali Type: Anomaly Product: Splunk Enterprise Security

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.

Search

 1`cisco_ios`
 2facility IN ("HA_EM", "PARSER")
 3mnemonic IN ("LOG", "CFGLOG_LOGGEDCMD")
 4message_text IN ("*interface Tunnel*", "*tunnel source*", "*tunnel destination*", "*ip address 10.10.12.*")
 5
 6| rex field=message_text "^(?:[^:]+:\s+)?(?:catchall:\s+)?(?<eem_command>.+?)\s*$"
 7
 8| rex field=message_text "<enteredCommand><cli>(?<parser_command>.*?)</cli>"
 9
10| rex field=message_text "<user>(?<parser_user>[^<]+)</user>"
11
12| rex field=message_text "<srcIP>(?<parser_src_ip>[^<]+)</srcIP>"
13
14| eval command=lower(trim(coalesce(parser_command, eem_command, "")))
15
16| eval event_type=case(
17    match(command, "^interface\s+tunnel"), "interface_tunnel",
18    match(command, "^tunnel\s+source"), "tunnel_source",
19    match(command, "^tunnel\s+destination"), "tunnel_destination",
20    match(command, "^ip\s+address\s+10\.10\.12\."), "tunnel_ip_address",
21    true(), null())
22
23| where isnotnull(event_type)
24
25| eval user=coalesce(parser_user, user, "unknown")
26
27| eval src_ip=coalesce(parser_src_ip, src_ip, "unknown")
28
29| eval dest=coalesce(host, dvc, dest, "unknown")
30
31| bin _time span=15m
32
33| stats count min(_time) as firstTime
34              max(_time) as lastTime
35              values(event_type) as event_types
36              values(user) as user
37              values(src_ip) as src_ip
38              values(command) as commands
39  by _time dest
40
41| where mvfind(event_types, "interface_tunnel") >= 0
42        AND
43        mvfind(event_types, "tunnel_source") >= 0
44        AND
45        mvfind(event_types, "tunnel_destination") >= 0
46        AND
47        mvfind(event_types, "tunnel_ip_address") >= 0
48
49| `security_content_ctime(firstTime)`
50
51| `security_content_ctime(lastTime)`
52
53| `cisco_ios_xe_tunnel_interface_configuration_filter`

Data Source

Name	Platform	Sourcetype	Source
Cisco IOS Logs	Other	`'cisco:ios'`	`'cisco:ios'`

Macros Used

Name	Value
cisco_ios	`sourcetype=cisco:ios`
cisco_ios_xe_tunnel_interface_configuration_filter	`search *`

cisco_ios_xe_tunnel_interface_configuration_filter is an empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.

Annotations

- MITRE ATT&CK

+ Kill Chain Phases

+ NIST

+ CIS

- Threat Actors

ID	Technique	Tactic
T1090	Proxy	Command and Control
T1572	Protocol Tunneling	Command and Control

Command and Control

DE.AE

CIS 13

Default Configuration

This detection is configured by default in Splunk Enterprise Security to run with the following settings:

Setting	Value
Disabled	true
Cron Schedule	`0 * * * *`
Earliest Time	`-70m@m`
Latest Time	`-10m@m`
Schedule Window	`auto`
Creates Finding (Notable)	No
Creates Intermediate Finding (Risk Event)	Yes

Anomaly detections generate Intermediate Findings (Risk Events). They do not generate a Finding (Notable) directly.

Implementation

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.

Associated Analytic Story

Salt Typhoon

Intermediate Findings

Message	Entity Field	Entity Type	Risk Score
Cisco IOS-XE tunnel interface configuration matching Salt Typhoon notes was observed on $dest$ by $user$.	dest	system	20

Threat Objects

Field	Type
commands	command

References

Detection Testing

Test Type	Status	Dataset	Source	Sourcetype
Validation	✅ Passing	N/A	N/A	N/A
Unit	✅ Passing	Dataset	`ctb:catalyst:syslog`	`cisco:ios`
Integration	✅ Passing	Dataset	`ctb:catalyst:syslog`	`cisco:ios`

Replay any dataset to Splunk Enterprise by using our replay.py tool or the UI. Alternatively you can replay a dataset into a Splunk Attack Range

Source: GitHub | Version: 1