200-201 Security Monitoring Practice Question
A SOC analyst is reviewing Cisco Firepower intrusion event logs and notices a signature that fired with the message 'OS-COMMAND' on traffic destined to an internal web server on TCP port 80. Which type of activity does this signature most likely indicate?
⚠ Common exam trap
The trap here is assuming any high-severity alert on port 80 is web exploitation generically, rather than recognizing that the OS-COMMAND signature category specifically flags operating system command execution attempts.
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 remote command injection attempt against a web application
An OS-COMMAND signature on HTTP traffic to a web server indicates an application-layer command injection attempt, where an attacker embeds operating system commands in a request to execute them on the target. The port and signature category align with this interpretation, making the remote command injection scenario the correct reading of the alert.
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 DNS tunneling session exfiltrating data to an external resolver
Why it's wrong here
DNS tunneling would generate traffic to port 53 and would typically trigger DNS-related signatures, not an OS-COMMAND signature on HTTP port 80. The destination port and signature category here do not match the characteristics of DNS exfiltration, which relies on encoded query names rather than HTTP command strings.
- ✗
A brute-force authentication attempt against the web server's SSH service
Why it's wrong here
Brute-force SSH activity targets TCP port 22 and produces authentication failure events, not an OS-COMMAND signature on port 80. The signature category and the HTTP destination port point away from credential brute forcing and toward application-layer command execution attempts.
- ✓
A remote command injection attempt against a web application
Why this is correct
Signatures with the 'OS-COMMAND' prefix in Cisco Firepower/SNORT rule sets are designed to detect attempts to execute operating system commands through an application, commonly via web request parameters. The traffic targeting port 80 on a web server strongly supports a command injection attempt, where an attacker tries to pass shell commands through an HTTP request to gain execution on the host.
- ✗
A normal software update check initiated by the web server
Why it's wrong here
Legitimate update checks usually go outbound from the server to vendor endpoints and would not match an OS-COMMAND injection signature. The signature is specifically written to catch shell metacharacters or command strings in application input, which is not typical of routine update traffic.
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JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official Cisco exam blueprint
This 200-201 practice question is part of Courseiva's free Cisco 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 200-201 exam.