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

Definição

What is CWE-1331?

This vulnerability occurs when a Network on Chip (NoC) fails to properly separate its internal, shared resources—like buffers, switches, and channels—between trusted and untrusted components. This lack of isolation creates a timing side-channel, allowing untrusted agents to potentially infer sensitive data from trusted ones.

Network on Chips are designed with many shared internal resources to handle data packets from different sources. When resources like internal buffers, crossbars, individual ports, and communication channels are not securely partitioned between trusted and untrusted domains, they become points of contention. This shared access introduces interference, which an attacker can measure and analyze to create a timing channel, potentially leaking information about the trusted agent's activities. The security threat here is twofold. First, it directly enables side-channel attacks where an attacker can deduce sensitive information by observing timing variations. Second, this improper isolation can cause significant performance degradation, as network interference from untrusted domains reduces overall system throughput and increases latency for legitimate traffic.

Impacto no mundo real

Real-world CVEs caused by CWE-1331

CVE-2021-33096

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

Como os atacantes a exploram

Trajeto do atacante passo a passo

1
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.
2
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.
3
Since this is a one-dimensional mesh, only one flow can use the link in each cycle. Also, packets from the attack program and the RSA program share the output port of the network-on-chip. This contention results in network interference, and the throughput and latency of one flow can be affected by the other flow's demand.
4
There may be different ways to fix this particular weakness.

Exemplo de código vulnerável

Vulnerable code

Since this is a one-dimensional mesh, only one flow can use the link in each cycle. Also, packets from the attack program and the RSA program share the output port of the network-on-chip. This contention results in network interference, and the throughput and latency of one flow can be affected by the other flow's demand.

Vulnerável

The attacker runs a loop program on the core they control, and this causes a cache miss in every iteration for the RSA algorithm. Thus, by observing network-traffic bandwidth and timing, the attack program can determine when the RSA algorithm is doing a multiply operation (i.e., when the secret key bit is 1) and eventually extract the entire, secret key.

Payload do atacante

Since this is a one-dimensional mesh, only one flow can use the link in each cycle. Also, packets from the attack program and the RSA program share the output port of the network-on-chip. This contention results in network interference, and the throughput and latency of one flow can be affected by the other flow's demand.

Payload do atacante

The attacker runs a loop program on the core they control, and this causes a cache miss in every iteration for the RSA algorithm. Thus, by observing network-traffic bandwidth and timing, the attack program can determine when the RSA algorithm is doing a multiply operation (i.e., when the secret key bit is 1) and eventually extract the entire, secret key.

Exemplo de código seguro

Secure Other

There may be different ways to fix this particular weakness.

Seguro Other

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

What changed: the unsafe sink is replaced (or the input is validated/escaped) so the same payload no longer triggers the weakness.

Lista de verificação de prevenção

How to prevent CWE-1331

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

Sinais de deteção

How to detect CWE-1331

Manual Analysis Moderate

Providing marker flags to send through the interfaces coupled with examination of which users are able to read or manipulate the flags will help verify that the proper isolation has been achieved and is effective.

CWE-1331

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Perguntas frequentes

Frequently asked questions

O que é o CWE-1331?

This vulnerability occurs when a Network on Chip (NoC) fails to properly separate its internal, shared resources—like buffers, switches, and channels—between trusted and untrusted components. This lack of isolation creates a timing side-channel, allowing untrusted agents to potentially infer sensitive data from trusted ones.

Qual a gravidade do CWE-1331?

A MITRE não publicou uma classificação de probabilidade de exploração para esta fraqueza. Trate-a como impacto médio até o seu modelo de ameaças provar o contrário.

Que linguagens ou plataformas são afetadas pelo CWE-1331?

MITRE lists the following affected platforms: Not OS-Specific, Not Architecture-Specific, Security Hardware, Not Technology-Specific.

Como posso prevenir o CWE-1331?

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

Como é que o Plexicus deteta e corrige o CWE-1331?

O motor SAST do Plexicus correlaciona a assinatura de fluxo de dados do CWE-1331 em cada commit. Quando é encontrada uma correspondência, o nosso agente Codex Remedium abre um PR de correção com o código corrigido, testes e um resumo de uma linha para o revisor.

Onde posso saber mais sobre o CWE-1331?

A MITRE publica a definição canónica em https://cwe.mitre.org/data/definitions/1331.html. Pode também consultar a documentação da OWASP e do NIST para orientações adjacentes.

Fraquezas relacionadas

Weaknesses related to CWE-1331

CWE-653 Pai

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CWE-1189 Irmão

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Recursos

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Improper Isolation of Shared Resources in Network On Chip (NoC)