Quick Answer
The answer is multiple failed login attempts leading to account lockout, unexpected software installations, and unusual outbound network traffic. These three indicators of a compromised system are correct because they directly reflect unauthorized access attempts, malware deployment, and data exfiltration—core attack behaviors that disrupt normal system integrity. On the ISC2 Certified in Cybersecurity CC exam, this concept tests your ability to distinguish between benign anomalies and genuine security incidents; a common trap is confusing a single failed login with a brute-force attack, but lockouts confirm systematic probing. For memory, think of the triad "Lock, Load, Leak"—lockouts signal credential attacks, unexpected software loads malware, and unusual traffic leaks data.
This CC practice question tests your understanding of security operations. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
Which THREE are common indicators of a compromised system? (Select THREE.)
Unexpected software installations
Malware often installs without user consent.
Unusual outbound network connections
Often indicative of command and control or data exfiltration.
High CPU usage during business hours
Why wrong: Could be legitimate heavy usage.
System uptime greater than 30 days
Why wrong: This is common for servers; not an indicator.
Multiple failed login attempts leading to account lockout
Indicates a brute-force attack.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
Unexpected software installations
Unexpected software installations are a common indicator of compromise because attackers often deploy malware, backdoors, or remote access tools (RATs) without user consent. In a CC context, this aligns with the principle that unauthorized software changes signal a breach, as legitimate installations typically follow change management processes. The presence of unknown executables or services in the system's process list or startup entries is a red flag.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
Unexpected software installations
Why this is correct
Malware often installs without user consent.
Related concept
Read the scenario before looking for a memorised answer.
Unusual outbound network connections
Why this is correct
Often indicative of command and control or data exfiltration.
Related concept
Read the scenario before looking for a memorised answer.
High CPU usage during business hours
Why it's wrong here
Could be legitimate heavy usage.
System uptime greater than 30 days
Why it's wrong here
This is common for servers; not an indicator.
Multiple failed login attempts leading to account lockout
Why this is correct
Indicates a brute-force attack.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
ISC2 often tests the distinction between symptoms of normal operations (e.g., high CPU usage during business hours) and true indicators of compromise, tricking candidates into selecting benign metrics as signs of a breach.
Detailed technical explanation
Unusual outbound network connections often involve traffic to known malicious IP addresses or on non-standard ports, which can be detected using netstat or SIEM tools. Multiple failed login attempts leading to account lockout are a classic sign of brute-force attacks, where attackers systematically try passwords against user accounts, triggering Windows or Linux security event IDs like 4625 or auth.log entries. These indicators are part of the Cyber Kill Chain's 'Actions on Objectives' or 'Exploitation' phases.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
A security analyst at a medium-sized enterprise encounters this scenario during an investigation or architecture review. The correct answer reflects best practice for the specific threat or control described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Security exam questions test whether you can match controls to threats in context — not just recall definitions.
What to study next
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FAQ
Security Operations — This question tests Security Operations — Read the scenario before looking for a memorised answer..
The correct answer is: Unexpected software installations — Unexpected software installations are a common indicator of compromise because attackers often deploy malware, backdoors, or remote access tools (RATs) without user consent. In a CC context, this aligns with the principle that unauthorized software changes signal a breach, as legitimate installations typically follow change management processes. The presence of unknown executables or services in the system's process list or startup entries is a red flag.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 30, 2026
This CC practice question is part of Courseiva's free ISC2 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 CC exam.
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