Cobalt Strike's ExternalC2 framework vs AzureC2Relay: 2026 Comparison
Cobalt Strike's ExternalC2 framework is a free offensive security tool. AzureC2Relay is a free offensive security tool. Compare features, ratings, integrations, and community reviews side by side to find the best offensive security fit for your security stack.
CST VerdictBased on our analysis of available product data, here is our conclusion:
Cobalt Strike's ExternalC2 framework
Red team operators and penetration testers who need to test defenses against custom C2 channels will use ExternalC2 to bypass network detection by routing Cobalt Strike traffic through external redirectors and custom protocols. The framework is free and lets you replace Cobalt Strike's default HTTP/HTTPS beaconing entirely, which means your C2 can blend into legitimate traffic patterns your client's sensors won't flag. Skip this if your team runs assessments using only default Cobalt Strike profiles or lacks the network infrastructure to host and manage external redirectors; the setup friction and operational complexity only pay off when you're specifically validating detection gaps around custom C2 communications.
Red teamers and penetration testers running Cobalt Strike campaigns through Azure need AzureC2Relay to hide C2 traffic behind legitimate cloud infrastructure without burning blue team detections on obviously malicious beacon patterns. The tool validates traffic against your Malleable C2 profile before relaying through an Azure Function, meaning only properly authenticated beacons get through; attackers often skip this layer and get caught on the first anomalous request. Skip this if you're not already deeply comfortable with Azure Functions, Malleable C2 profiles, and infrastructure-as-code deployments; the 236 GitHub stars reflect a small, skilled audience rather than a tool that abstracts away operator complexity.
