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.

Techniques

Sample rules

Cisco TFTP Server Configuration for Data Exfiltration

source: splunk
technicques:
- T1567
- T1005

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.

Detection logic


| 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`