An adversary which has gained elevated access to network boundary devices may use these devices to create a channel to bridge trusted and untrusted networks. Boundary devices do not necessarily have to be on the network’s edge, but rather must serve to segment portions of the target network the adversary wishes to cross into.
Extended Description
Network boundary devices are network devices such as routers and firewalls which segment networks by restricting certain types of traffic from flowing through the device. Network boundary devices are often directly accessible through a portal page for management purposes. An adversary’s goal when conducting network boundary bridging is to connect networks which are being segmented by the device. To do so, the adversary must first compromise the network boundary device.
Likelihood Of Attack
Medium
Typical Severity
High
Relationships
This table shows the other attack patterns and high level categories that are related to this attack pattern. These relationships are defined as ChildOf and ParentOf, and give insight to similar items that may exist at higher and lower levels of abstraction. In addition, relationships such as CanFollow, PeerOf, and CanAlsoBe are defined to show similar attack patterns that the user may want to explore.
Nature
Type
ID
Name
ChildOf
Meta Attack Pattern - A meta level attack pattern in CAPEC is a decidedly abstract characterization of a specific methodology or technique used in an attack. A meta attack pattern is often void of a specific technology or implementation and is meant to provide an understanding of a high level approach. A meta level attack pattern is a generalization of related group of standard level attack patterns. Meta level attack patterns are particularly useful for architecture and design level threat modeling exercises.
Detailed Attack Pattern - A detailed level attack pattern in CAPEC provides a low level of detail, typically leveraging a specific technique and targeting a specific technology, and expresses a complete execution flow. Detailed attack patterns are more specific than meta attack patterns and standard attack patterns and often require a specific protection mechanism to mitigate actual attacks. A detailed level attack pattern often will leverage a number of different standard level attack patterns chained together to accomplish a goal.
Meta Attack Pattern - A meta level attack pattern in CAPEC is a decidedly abstract characterization of a specific methodology or technique used in an attack. A meta attack pattern is often void of a specific technology or implementation and is meant to provide an understanding of a high level approach. A meta level attack pattern is a generalization of related group of standard level attack patterns. Meta level attack patterns are particularly useful for architecture and design level threat modeling exercises.
Identify potential targets: An adversary identifies network boundary devices that can be compromised.
Techniques
The adversary traces network traffic to identify which devices the traffic flows through. Additionally, the adversary can identify devices using fingerprinting methods or locating the management page to determine identifying information about the device.
Experiment
Compromise targets: The adversary must compromise the identified targets in the previous step.
Techniques
Once the device is identified, the adversary can attempt to input known default credentials for the device to gain access to the management console.
Adversaries with sufficient identifying knowledge about the target device can exploit known vulnerabilities in network devices to obtain administrative access.
Exploit
Bridge Networks: The adversary changes the configuration of the compromised network device to connect the networks the device was segmenting. Depending on the type of network boundary device and its capabilities, bridging can be implemented using various methods.
Techniques
The adversary can abuse Network Address Translation (NAT) in firewalls and routers to manipulate traffic flow to their own design. With control of the network device, the adversary can manipulate NAT by either using existing configurations or creating their own to allow two previously unconnected networks to communicate.
Some network devices can be configured to become a proxy server. Adversaries can set up or exploit an existing proxy server on compromised network devices to create a bridge between separate networks.
Prerequisites
The adversary must have control of a network boundary device.
Skills Required
[Level: Medium]
The adversary must understand how to manage the target network device to create or edit policies which will bridge networks.
Resources Required
The adversary requires either high privileges or full control of a boundary device on a target network.
Consequences
This table specifies different individual consequences associated with the attack pattern. The Scope identifies the security property that is violated, while the Impact describes the negative technical impact that arises if an adversary succeeds in their attack. The Likelihood provides information about how likely the specific consequence is expected to be seen relative to the other consequences in the list. For example, there may be high likelihood that a pattern will be used to achieve a certain impact, but a low likelihood that it will be exploited to achieve a different impact.
Scope
Impact
Likelihood
Confidentiality
Access Control
Read Data
Bypass Protection Mechanism
Integrity
Authorization
Alter Execution Logic
Hide Activities
Mitigations
Design: Ensure network devices are storing credentials in encrypted stores
Design: Follow the principle of least privilege and restrict administrative duties to as few accounts as possible. Ensure these privileged accounts are secured with strong credentials which do not overlap with other network devices.
Configuration: When possible, configure network boundary devices to use MFA.
Configuration: Change the default configuration for network devices to harden their security profiles. Default configurations are often enabled with insecure features to allow ease of installation and management. However, these configurations can be easily discovered and exploited by adversaries.
Implementation: Perform integrity checks on audit logs for network device management and review them to identify abnormalities in configurations.
Implementation: Prevent network boundary devices from being physically accessed by unauthorized personnel to prevent tampering.
Example Instances
In November 2016, a Smart Install Exploitation Tool was released online which takes advantage of Cisco’s unauthenticated SMI management protocol to download a target’s current configuration files. Adversaries can use this tool to overwrite files to modify the device configurations, or upload maliciously modified OS or firmware to enable persistence. Once the adversary has access to the device’s configurations, they could modify it to redirect network traffic through other network infrastructure.
Related Weaknesses
A Related Weakness relationship associates a weakness with this attack pattern. Each association implies a weakness that must exist for a given attack to be successful. If multiple weaknesses are associated with the attack pattern, then any of the weaknesses (but not necessarily all) may be present for the attack to be successful. Each related weakness is identified by a CWE identifier.
Some type of access control weakness (CWE-284 or its descendants) is related to this CAPEC, probably as a prerequisite.
Taxonomy Mappings
CAPEC mappings to ATT&CK techniques leverage an inheritance model to streamline and minimize direct CAPEC/ATT&CK mappings. Inheritance of a mapping is indicated by text stating that the parent CAPEC has relevant ATT&CK mappings. Note that the ATT&CK Enterprise Framework does not use an inheritance model as part of the mapping to CAPEC.
Description
This table shows the other attack patterns and high level categories that are related to this attack pattern. These relationships are defined as ChildOf and ParentOf, and give insight to similar items that may exist at higher and lower levels of abstraction. In addition, relationships such as CanFollow, PeerOf, and CanAlsoBe are defined to show similar attack patterns that the user may want to explore.
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