Cisco TFTP Server Configuration for Data Exfiltration

name: Cisco TFTP Server Configuration for Data Exfiltration
id: 1abce487-f480-4d5f-a551-01de0bece0bd
version: 5
creation_date: '2025-08-21'
modification_date: '2026-05-13'
author: Bhavin Patel, Michael Haag, Splunk
status: production
type: TTP
description: This analytic detects the configuration of TFTP services on Cisco IOS devices that could be used to exfiltrate sensitive configuration files. Threat actors like Static Tundra have been observed configuring TFTP servers to make device configuration files accessible for exfiltration after gaining initial access. The detection specifically looks for commands that expose critical configuration files such as startup-config, running-config, and other sensitive system information through TFTP. This activity is particularly concerning as it may represent an attempt to steal credentials, network topology information, and other sensitive data stored in device configurations.
data_source:
    - Cisco IOS Logs
search: |-
    | tstats `security_content_summariesonly` count values(All_Changes.command) as command min(_time) as firstTime max(_time) as lastTime FROM datamodel=Change.All_Changes
      WHERE (
            All_Changes.command="*tftp-server*"
        )
        AND ( All_Changes.command="*nvram:startup-config*" OR All_Changes.command="*bootflash:running-config*" OR All_Changes.command="*system:running-config*" OR All_Changes.command="*bootflash:info*" OR All_Changes.command="*startup-config*" OR All_Changes.command="*running-config*" )
      BY All_Changes.dvc All_Changes.user
    | `drop_dm_object_name("All_Changes")`
    | rename dvc as dest
    | `security_content_ctime(firstTime)`
    | `security_content_ctime(lastTime)`
    | `cisco_tftp_server_configuration_for_data_exfiltration_filter`
how_to_implement: To implement this search, you need to be ingesting Cisco IOS logs with the sourcetype "cisco:ios" and have these logs mapped to the Change datamodel. Ensure that your Cisco IOS devices are configured to send logs to your Splunk environment, with appropriate logging levels enabled to capture command logging events (PARSER-5-CFGLOG_LOGGEDCMD). Configure command logging on Cisco IOS devices using the "archive log config logging enable" command.
known_false_positives: Legitimate TFTP server configurations may be detected by this analytic during authorized backup operations or device maintenance. Network administrators sometimes use TFTP for legitimate configuration backups, firmware updates, or during troubleshooting. To reduce false positives, consider implementing a baseline of expected administrative activities, including approved administrative usernames and scheduled maintenance windows.
references:
    - https://blog.talosintelligence.com/static-tundra/
    - https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-20180328-smi2
    - https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/fundamentals/command/cf_command_ref/T_through_X.html#wp3081407060
finding:
    title: Suspicious TFTP server configuration detected on Cisco device $dest$ by user $user$, potentially exposing sensitive configuration files
    entity:
        field: user
        type: user
        score: 50
intermediate_findings:
    entities:
        - field: dest
          type: system
          score: 50
          message: Suspicious TFTP server configuration detected on Cisco device $dest$ by user $user$, potentially exposing sensitive configuration files
threat_objects:
    - field: command
      type: command
analytic_story:
    - Cisco Smart Install Remote Code Execution CVE-2018-0171
asset_type: Network
cve:
    - CVE-2018-0171
mitre_attack_id:
    - T1567
    - T1005
product:
    - Splunk Enterprise
    - Splunk Enterprise Security
    - Splunk Cloud
category: network
security_domain: network