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Security Fundamentals & Crypto · Advanced

Covert Channel

Unauthorized communication path that transfers information in a way that violates security policy.

Definition

Covert storage channels hide data in shared resources such as file attributes or protocol fields, while covert timing channels encode data by modulating timing of events. They are hard to detect and are addressed by formal evaluation, isolation, and traffic analysis. Overt channels, by contrast, are legitimate communication paths.

Example

Malware exfiltrates data by encoding it in DNS query subdomains.

Exam tip

Know storage versus timing covert channels for CISSP.

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