CWE-1331: Improper Isolation of Shared Resources in Network On Chip (NoC)

Extended Description

Typically, network on chips (NoC) have many internal resources that are shared between packets from different trust domains. These resources include internal buffers, crossbars and switches, individual ports, and channels. The sharing of resources causes contention and introduces interference between differently trusted domains, which poses a security threat via a timing channel, allowing attackers to infer data that belongs to a trusted agent. This may also result in introducing network interference, resulting in degraded throughput and latency.

Code Examples & CVEs

Demonstrative Examples

Consider a NoC that implements a one-dimensional mesh network with four nodes. This supports two flows: Flow A from node 0 to node 3 (via node 1 and node 2) and Flow B from node 1 to node 2. Flows A and B share a common link between Node 1 and Node 2. Only one flow can use the link in each cycle.

One of the masters to this NoC implements a cryptographic algorithm (RSA), and another master to the NoC is a core that can be exercised by an attacker. The RSA algorithm performs a modulo multiplication of two large numbers and depends on each bit of the secret key. The algorithm examines each bit in the secret key and only performs multiplication if the bit is 1. This algorithm is known to be prone to timing attacks. Whenever RSA performs multiplication, there is additional network traffic to the memory controller. One of the reasons for this is cache conflicts.

GoodOther

Implement priority-based arbitration inside the NoC and have dedicated buffers or virtual channels for routing secret data from trusted agents.

Observed CVE Examples (1)

CVE-2021-33096

Improper isolation of shared resource in a network-on-chip leads to denial of service

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Source-backed guidance

Additional facts reviewed against primary or authoritative security sources.

Verify controls for CWE-1331 with SSDF evidence

Use NIST SSDF verification and vulnerability-response practices to detect CWE-1331, Improper Isolation of Shared Resources in Network On Chip (NoC), throughout the product lifecycle. Derive review questions, static or dynamic checks, and negative tests from the CWE's causal behavior; define the components and lifecycle stages each check covers; and retain findings with enough evidence to distinguish the root cause from symptoms and impacts. Track escapes and false negatives, then improve the verification plan after every confirmed occurrence.

NIST SP 800-218 Secure Software Development Framework — National Institute of Standards and Technology

Address Improper Isolation of Shared Resources in Network On Chip (NoC) during Architecture and Design

MITRE associates mitigation with Architecture and Design, and Implementation; documented detection approaches include Manual Analysis; recorded impacts include DoS: Resource Consumption (Other), Varies by Context, and Other. Use these source-defined anchors to turn CWE-1331 into implementation, review, and verification checks for the affected component.

CWE-1331: Improper Isolation of Shared Resources in Network On Chip (NoC) — MITRE CWE

Triage CWE-1331 against known exploitation evidence

Use CISA's Known Exploited Vulnerabilities catalog to test whether a vulnerability mapped to CWE-1331, Improper Isolation of Shared Resources in Network On Chip (NoC), has evidence of exploitation in the wild. Confirm the CVE-to-CWE root-cause mapping independently before attaching the example, then capture the affected product, required action, and remediation deadline. A missing KEV match is not evidence that the weakness is unexploited, and a KEV entry must not be generalized to every occurrence of this CWE.

Known Exploited Vulnerabilities Catalog — Cybersecurity and Infrastructure Security Agency

Apply precise root-cause mapping to CWE-1331

Apply MITRE's full root-cause mapping guidance when using CWE-1331, Improper Isolation of Shared Resources in Network On Chip (NoC). Separate weakness language from attacker prerequisites and technical impact, check the entry's abstraction and vulnerability-mapping notes, and prefer the most specific Base or Variant supported by the evidence. Record the rejected alternatives and require an independent review before the mapping is used for remediation trends or program metrics.

CVE to CWE Root Cause Mapping Guidance — MITRE CWE

Validate CWE-1331 with root-cause mapping checks

Apply MITRE's root-cause mapping quick tips to CWE-1331, Improper Isolation of Shared Resources in Network On Chip (NoC). Confirm the finding describes the causal weakness rather than an impact or attack pattern, compare the abstraction and mapping notes with plausible alternatives, and have a second reviewer challenge the selection. Preserve the evidence and reasoning so recurring defects can be measured against one consistent identifier.

CVE to CWE Root Cause Mapping Quick Tips — MITRE CWE

Frequently Asked Questions

What is CWE-1331: Improper Isolation of Shared Resources in Network On Chip (NoC)?+

CWE-1331: Improper Isolation of Shared Resources in Network On Chip (NoC) is a Common Weakness Enumeration (CWE) entry maintained by MITRE. The Network On Chip (NoC) does not isolate or incorrectly isolates its on-chip-fabric and internal resources such that they are shared between trusted and untrusted agents, creating timing channels. Typically, network on chips (NoC) have many internal resources that are shared between packets from different trust domains. These resources include internal buffers, crossbars and switches, individual ports, and channels. The sharing of resources causes contention and introduces interference between differently trusted domains, which poses a security threat via a timing channel, allowing attackers to infer data that belongs to a trusted agent. This may also result in introducing network interference, resulting in degraded throughput and latency.

What are the security consequences of Improper Isolation of Shared Resources in Network On Chip (NoC)?+

If exploited, CWE-1331 (Improper Isolation of Shared Resources in Network On Chip (NoC)) it can compromise Confidentiality and Availability, leading to outcomes such as DoS: Resource Consumption (Other), Varies by Context and Other.

How do you prevent or mitigate Improper Isolation of Shared Resources in Network On Chip (NoC)?+

Recommended mitigations for CWE-1331 include: Implement priority-based arbitration inside the NoC and have dedicated buffers or virtual channels for routing secret data from trusted agents.

How is Improper Isolation of Shared Resources in Network On Chip (NoC) detected?+

CWE-1331 can be detected using Manual Analysis. Combining automated tooling with manual review typically yields the best coverage.

Which programming languages are affected by Improper Isolation of Shared Resources in Network On Chip (NoC)?+

CWE-1331 commonly affects Not Language-Specific. Note that weaknesses are often language-agnostic patterns, so secure coding practices apply broadly.

What are real-world examples of Improper Isolation of Shared Resources in Network On Chip (NoC)?+

MITRE documents real CVEs mapped to CWE-1331, including CVE-2021-33096. You can look up the full details of each CVE, including CVSS scores and remediation guidance, on our CVE Lookup tool.

What is the difference between a CWE and a CVE?+

A CWE (Common Weakness Enumeration) like CWE-1331 describes a category of software weakness — the underlying flaw type. A CVE (Common Vulnerabilities and Exposures) identifies a specific, real-world vulnerability in a particular product. In short, a CWE is the kind of mistake, and a CVE is an instance of that mistake being found in software.

CWE-1331: Improper Isolation of Shared Resources in Network On Chip (NoC)

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