Detection Strategy for Patch System Image on Network Devices

Technique Detected:  Patch System Image | T1601.001

ID: DET0469
Domains: Enterprise
Analytics: AN1293
Version: 1.0
Created: 21 October 2025
Last Modified: 21 October 2025

Analytics

AN1293

Defenders may observe adversary attempts to patch system images by monitoring for anomalous file transfers (TFTP, SCP, FTP) of image files, unauthorized CLI commands altering boot system variables, integrity check mismatches between running and baseline OS images, and runtime memory manipulation attempts. Suspicious sequences include uploading a new image, modifying boot parameters, and subsequent reload/reboot of the device. In-memory patching attempts may manifest as debug commands or boot loader manipulation inconsistent with normal administrative activity.

Log Sources
Data Component Name Channel
Command Execution (DC0064) networkdevice:cli Execution of privileged commands such as 'copy tftp flash', 'boot system', or 'debug memory'
File Modification (DC0061) networkdevice:config Configuration changes to startup image paths, boot loader parameters, or debug flags
Firmware Modification (DC0004) firmware:runtime Debug or memory access commands indicating attempts to alter OS instructions in memory
Mutable Elements
Field Description
ApprovedFirmwareVersions Whitelist of validated vendor OS versions; deviations may indicate tampering.
AuthorizedAdminAccounts Trusted admin accounts permitted to update images; anomalies suggest compromise.
ChecksumBaseline Baseline hash of approved images; used for detecting file tampering.
TimeWindow Correlation period for detecting chained behaviors (file upload → boot config change → reboot).