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CISSP Practice Question: A security team is analyzing logs from multiple…
A security team is analyzing logs from multiple sources and notices anomalous outbound traffic to a known command-and-control server. What is the most likely conclusion?
⚠ Common exam trap
Candidates often confuse anomalous outbound traffic with a network misconfiguration or a benign user activity, failing to recognize that beaconing to a known malicious destination is a definitive sign of compromise, not a configuration error or a DDoS symptom.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
A host is compromised and is beaconing
Anomalous outbound traffic to a known command-and-control (C2) server is a classic indicator of compromise (IoC). Compromised hosts often beacon outbound to C2 infrastructure using HTTP, HTTPS, or DNS tunnels to receive instructions or exfiltrate data. This pattern is distinct from normal traffic and is a primary focus of network security monitoring and intrusion detection systems (IDS).
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
A misconfigured firewall is causing traffic
Why it's wrong here
A misconfigured firewall might inadvertently permit various types of outbound traffic or block legitimate services, but it would not inherently generate or cause an internal host to initiate patterned, periodic outbound connections to a specific, known Command and Control (C2) server. Firewall misconfigurations typically lead to unintended access or denial for a broad range of destinations, lacking the specific intent and consistent communication pattern characteristic of malware beaconing.
- ✓
A host is compromised and is beaconing
Why this is correct
This is the correct explanation. When a host is compromised by malware, it frequently establishes and maintains communication with its Command and Control (C2) server through a process known as beaconing. This involves sending small, periodic outbound packets to a specific external IP address or domain, often at regular intervals, to check for new instructions or exfiltrate data. This behavior is a strong indicator of compromise and is precisely what security teams look for in logs.
- ✗
An employee is streaming video to a personal server
Why it's wrong here
An employee streaming video, even to a personal server, would generate a continuous, high-bandwidth outbound data stream to a legitimate content delivery network (CDN) or a known personal IP address, not periodic, low-bandwidth 'beaconing' to a known malicious Command and Control (C2) server. The traffic pattern (continuous vs. periodic) and the nature of the destination (legitimate streaming service vs. known malicious infrastructure) are fundamentally different from C2 communication.
- ✗
The network is under a DDoS attack
Why it's wrong here
A Distributed Denial of Service (DDoS) attack is characterized by a massive influx of *inbound* traffic from numerous external sources, overwhelming a target network or service. It does not manifest as *outbound* beaconing from an internal host to a specific external Command and Control (C2) server. While a compromised host might be part of a botnet used for DDoS, the observed beaconing traffic is the host's communication with its controller, not the DDoS attack itself.
Go deeper
Related to this question
Learn chapter
Security Governance and Principles
Key term
Network security
Network security is the practice of protecting a computer network from unauthorized access, misuse, malfunction, modification, destruction, or improper disclosure, ensuring the confidentiality, integrity, and availability of data and resources.
Key term
Security
Security in IT is the practice of protecting systems, networks, and data from unauthorized access, damage, or theft.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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