Network Boundary Bridging
Sub-techniques (1)
Adversaries may bridge network boundaries by compromising perimeter network devices or internal devices responsible for network segmentation. Breaching these devices may enable an adversary to bypass restrictions on traffic routing that otherwise separate trusted and untrusted networks. Devices such as routers and firewalls can be used to create boundaries between trusted and untrusted networks. They achieve this by restricting traffic types to enforce organizational policy in an attempt to reduce the risk inherent in such connections. Restriction of traffic can be achieved by prohibiting IP addresses, layer 4 protocol ports, or through deep packet inspection to identify applications. To participate with the rest of the network, these devices can be directly addressable or transparent, but their mode of operation has no bearing on how the adversary can bypass them when compromised. When an adversary takes control of such a boundary device, they can bypass its policy enforcement to pass normally prohibited traffic across the trust boundary between the two separated networks without hinderance. By achieving sufficient rights on the device, an adversary can reconfigure the device to allow the traffic they want, allowing them to then further achieve goals such as command and control via Multi-hop Proxy or exfiltration of data via Traffic Duplication. Adversaries may also target internal devices responsible for network segmentation and abuse these in conjunction with Internal Proxy to achieve the same goals.(Citation: Kaspersky ThreatNeedle Feb 2021) In the cases where a border device separates two separate organizations, the adversary can also facilitate lateral movement into new victim environments.
Procedure Examples |
|
| Name | Description |
|---|---|
| APT41 |
APT41 used `NATBypass` to bypass firewall restrictions and to access compromised systems via RDP.(Citation: apt41_dcsocytec_dec2022) |
Mitigations |
|
| Mitigation | Description |
|---|---|
| Multi-factor Authentication |
Use two or more pieces of evidence to authenticate to a system; such as username and password in addition to a token from a physical smart card or token generator. |
| Password Policies |
Set and enforce secure password policies for accounts. |
| Privileged Account Management |
Manage the creation, modification, use, and permissions associated to privileged accounts, including SYSTEM and root. |
| Filter Network Traffic |
Use network appliances to filter ingress or egress traffic and perform protocol-based filtering. Configure software on endpoints to filter network traffic. |
| Credential Access Protection |
Use capabilities to prevent successful credential access by adversaries; including blocking forms of credential dumping. |
Detection
Consider monitoring network traffic on both interfaces of border network devices with out-of-band packet capture or network flow data, using a different device than the one in question. Look for traffic that should be prohibited by the intended network traffic policy enforcement for the border network device. Monitor the border network device’s configuration to validate that the policy enforcement sections are what was intended. Look for rules that are less restrictive, or that allow specific traffic types that were not previously authorized.
References
- Vyacheslav Kopeytsev and Seongsu Park. (2021, February 25). Lazarus targets defense industry with ThreatNeedle. Retrieved October 27, 2021.
- Cisco. (n.d.). Cisco IOS Software Integrity Assurance - TACACS. Retrieved October 19, 2020.
- Grassi, P., et al. (2017, December 1). SP 800-63-3, Digital Identity Guidelines. Retrieved January 16, 2019.
- DCSO CyTec Blog. (2022, December 24). APT41 — The spy who failed to encrypt me. Retrieved June 13, 2024.
- Cisco. (n.d.). Cisco IOS Software Integrity Assurance - AAA. Retrieved October 19, 2020.
Связанные риски
Каталоги
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