Features, pricing, ratings, and pros and cons, compared head to head.
Act Free Assessment is a free breach & attack simulation tool by Act. Cobalt Strike's ExternalC2 framework is a free red-team & adversary emulation tool. Compare features, ratings, integrations, and community reviews side by side to find the best breach & attack simulation fit for your security stack. Independent and vendor-neutral: our scores and rankings are earned, never bought — sponsored placement is always labeled.
Based on our analysis of NIST CSF 2.0 coverage, core features, company size fit, deployment model, 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.
Free read-only cloud attack path simulation covering 5 real attack scenarios.
A specification/framework for extending default C2 communication channels in Cobalt Strike
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Common questions about comparing Act Free Assessment vs Cobalt Strike's ExternalC2 framework for your breach & attack simulation needs.
Act Free Assessment: Free read-only cloud attack path simulation covering 5 real attack scenarios. built by Act. Core capabilities include Read-only, agentless attack simulation deployed in under 5 minutes, 5 real attack scenarios validated in the customer's live environment, Step-by-step access chain visualization from entry points to production data..
Cobalt Strike's ExternalC2 framework: A specification/framework for extending default C2 communication channels in Cobalt Strike..
Both serve the Breach & Attack Simulation market but differ in approach, feature depth, and target audience.
Act Free Assessment and Cobalt Strike's ExternalC2 framework serve similar Breach & Attack Simulation use cases. Review the feature comparison above to determine which fits your requirements.
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