CS0-003 Security Operations Practice Question
An analyst is reviewing a YARA rule that triggers on a specific string pattern in memory. The rule has a high false positive rate. Which of the following actions would best reduce false positives while maintaining detection capability?
⚠ Common exam trap
The trap here is assuming that any change to the rule (converting format, lengthening strings, or disabling it) will reduce false positives, when only adding a logical co-occurrence condition preserves detection while improving precision.
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
✓
Add a condition that requires the string to appear with another indicator
YARA false positives occur when a single string pattern is too generic and matches benign files. Adding a condition that requires the string to co-occur with another indicator (for example, using 'and' or proximity operators like '2 of them' or 'all of them') increases specificity while preserving the ability to detect the malicious pattern. This is the standard YARA tuning technique because it raises the rule's precision without discarding the detection logic.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Add a condition that requires the string to appear with another indicator
Why this is correct
Adding logical conditions, such as requiring the presence of an auxiliary malicious string or a specific file header, increases the rule's specificity. This multi-indicator approach significantly reduces false positives by ensuring the rule only triggers when a combination of unique threat characteristics is met, rather than a single, potentially benign string.
- ✗
Convert the rule to a Sigma rule
Why it's wrong here
Converting the logic to a Sigma rule is inappropriate because Sigma is a generic signature format designed for querying log files and SIEM events. YARA is specifically built for scanning files, process memory, and binary payloads, making Sigma incapable of performing the raw byte-level or string-matching analysis required here.
- ✗
Remove the rule from active use
Why it's wrong here
Completely disabling or removing the YARA rule from active deployment eliminates the organization's ability to detect the targeted threat vector. While this action stops the immediate false positives, it leaves a critical security blind spot and exposes the environment to undetected intrusions by the associated malware family.
- ✗
Increase the string length in the rule
Why it's wrong here
Simply lengthening the target string can easily lead to evasion because malware authors frequently modify non-functional parts of their code or use different packers. This approach creates a brittle signature that fails to detect minor variants or updated versions of the same threat, compromising overall detection efficacy.
Go deeper
Related to this question
Learn chapter
Memory Forensics and Volatile Data
Key term
Detection
Detection is the process of identifying potential security incidents or anomalies by analyzing system data, logs, and network traffic.
Key term
YARA
YARA is a pattern-matching tool used by cybersecurity professionals to identify and classify malware based on textual or binary patterns.
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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 CompTIA exam blueprint
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.