Monitoring outbound traffic is essential for detecting unauthorized data exfiltration from a system. A new vulnerability that allows malware to move data unauthorizedly would typically attempt to send this data out of the network. By monitoring outbound traffic, security tools can detect unusual data transfers, trigger alerts, and help prevent the exfiltration of sensitive information.
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CompTIA Security+ SY0-701 Course Content: Domain 04 Security Operations.
CompTIA Security+ SY0-601 Study Guide: Chapter on Threat Detection and Response.