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T1601 Modify System Image

Adversaries may make changes to the operating system of embedded network devices to weaken defenses and provide new capabilities for themselves. On such devices, the operating systems are typically monolithic and most of the device functionality and capabilities are contained within a single file.

To change the operating system, the adversary typically only needs to affect this one file, replacing or modifying it. This can either be done live in memory during system runtime for immediate effect, or in storage to implement the change on the next boot of the network device.

Item Value
ID T1601
Sub-techniques T1601.001, T1601.002
Tactics TA0005
Platforms Network
Permissions required Administrator
Version 1.0
Created 19 October 2020
Last Modified 22 October 2020

Mitigations

ID Mitigation Description
M1046 Boot Integrity Some vendors of embedded network devices provide cryptographic signing to ensure the integrity of operating system images at boot time. Implement where available, following vendor guidelines. 3
M1045 Code Signing Many vendors provide digitally signed operating system images to validate the integrity of the software used on their platform. Make use of this feature where possible in order to prevent and/or detect attempts by adversaries to compromise the system image. 4
M1043 Credential Access Protection Some embedded network devices are capable of storing passwords for local accounts in either plain-text or encrypted formats. Ensure that, where available, local passwords are always encrypted, per vendor recommendations. 6
M1032 Multi-factor Authentication Use multi-factor authentication for user and privileged accounts. Most embedded network devices support TACACS+ and/or RADIUS. Follow vendor prescribed best practices for hardening access control.7
M1027 Password Policies Refer to NIST guidelines when creating password policies. 5
M1026 Privileged Account Management Restrict administrator accounts to as few individuals as possible, following least privilege principles. Prevent credential overlap across systems of administrator and privileged accounts, particularly between network and non-network platforms, such as servers or endpoints.

Detection

ID Data Source Data Component
DS0022 File File Modification

References

  1. Cisco. (n.d.). Cisco IOS Software Integrity Assurance - Cisco IOS Image File Verification. Retrieved October 19, 2020. ↩

  2. Cisco. (n.d.). Cisco IOS Software Integrity Assurance - Cisco IOS Run-Time Memory Integrity Verification. Retrieved October 19, 2020. ↩

  3. Cisco. (n.d.). Cisco IOS Software Integrity Assurance - Secure Boot. Retrieved October 19, 2020. ↩

  4. Cisco. (n.d.). Cisco IOS Software Integrity Assurance - Deploy Signed IOS. Retrieved October 21, 2020. ↩

  5. Grassi, P., et al. (2017, December 1). SP 800-63-3, Digital Identity Guidelines. Retrieved January 16, 2019. ↩

  6. Cisco. (n.d.). Cisco IOS Software Integrity Assurance - Credentials Management. Retrieved October 19, 2020. ↩

  7. Cisco. (n.d.). Cisco IOS Software Integrity Assurance - TACACS. Retrieved October 19, 2020. ↩