SCS-C02 Threat Detection and Incident Response Practice Question
A company uses Amazon GuardDuty and receives a finding of type 'Backdoor:EC2/C&CActivity.B!DNS' for an EC2 instance. What does this finding indicate?
⚠ Common exam trap
Test-takers frequently confuse 'Backdoor:EC2/C&CActivity.B!DNS' with generic network anomalies or other attack types, but the key differentiator is the DNS-specific indicator that pinpoints communication with a known command and control server, not the attack vector or data exfiltration method.
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
✓
The instance is communicating with a known command and control server.
The finding 'Backdoor:EC2/C&CActivity.B!DNS' indicates that GuardDuty has detected DNS queries from the EC2 instance to a domain associated with known command and control (C&C) infrastructure. This is based on GuardDuty's threat intelligence feeds that map DNS request patterns to known malicious domains, signaling that the instance may be compromised and communicating with an attacker's server.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
The instance is being targeted by an SSH brute force attack.
Why it's wrong here
SSH brute force would be 'UnauthorizedAccess:EC2/SSHBruteForce'.
- ✓
The instance is communicating with a known command and control server.
Why this is correct
The finding name indicates C&C activity detected via DNS.
- ✗
The instance is exfiltrating data to an S3 bucket.
Why it's wrong here
Data exfiltration to S3 would be detected as a different finding type.
- ✗
The instance is being used in a DDoS attack.
Why it's wrong here
DDoS typically involves high traffic volumes, not necessarily C&C communication.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This SCS-C02 practice question is part of Courseiva's free Amazon Web Services certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the SCS-C02 exam.