CS0-003 Security Operations Practice Question
A SOC analyst is triaging a SIEM alert for a registry modification on a workstation. The alert indicates a new Run key was added under HKCU\Software\Microsoft\Windows\CurrentVersion\Run. Which of the following is the most likely purpose of this modification?
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
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To establish persistence
Run keys are a common persistence mechanism used by malware to ensure execution at user logon.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
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To change the desktop wallpaper
Why it's wrong here
While desktop background configurations are indeed managed via the registry, they are specifically located under the Control Panel\Desktop subkey, such as the Wallpaper string value. Modifying a standard startup or Run key would not alter the visual desktop background directly, making this an incorrect interpretation of the alert's intent. Instead, such modifications are indicative of execution rather than cosmetic customization.
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To establish persistence
Why this is correct
Threat actors frequently target registry Run and RunOnce keys located within HKLM or HKCU to ensure their malicious payloads execute automatically upon system boot or user logon. This mechanism allows the malware to survive system reboots and maintain a continuous presence within the compromised environment. Consequently, detecting unauthorized modifications to these specific registry paths is a high-fidelity indicator of a persistence establishment attempt.
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To disable Windows Defender
Why it's wrong here
Disabling or tampering with Windows Defender is typically achieved by modifying policies under HKLM\SOFTWARE\Policies\Microsoft\Windows Defender or stopping the associated system services. While this is a common defense evasion tactic, it relies on entirely different registry hives and keys than the Run keys targeted for startup execution. Therefore, a Run key modification alert would not directly indicate the disabling of antivirus defenses.
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To update the system time
Why it's wrong here
System time synchronization and time zone configurations are managed by the Windows Time service and its corresponding parameters located under HKLM\SYSTEM\CurrentControlSet\Services\W32Time. Modifying user or machine Run keys has no functional impact on the system clock or network time protocol settings. Analysts would look for changes in system services or specific time-provider registry keys to investigate unauthorized time modifications.
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Related to this question
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Software Bill of Materials (SBOM)
Key term
Persistence
Persistence is the set of techniques attackers use to maintain long-term access to a compromised system even after reboots or credential changes.
Key term
SIEM
SIEM (Security Information and Event Management) is a system that collects and analyzes log data from across an IT environment to detect and respond to security threats in real time.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This CS0-004 practice question is part of Courseiva's free CompTIA 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 CS0-004 exam.