hardMultiple ChoiceObjective-mapped
CISA Practice Question: A company's endpoint protection solution alerts…
A company's endpoint protection solution alerts on a file that is digitally signed by a trusted software vendor but exhibits malicious behavior on execution. What type of threat does this scenario most likely depict?
⚠ Common exam trap
Test-takers frequently confuse 'signed malware' with a 'Trojan horse,' but the critical differentiator is the presence of a valid digital signature from a trusted vendor, which is not inherent to Trojans and is the specific mechanism that makes this threat unique.
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
✓
Signed malware, indicating the certificate may have been compromised.
The scenario describes a file that is digitally signed by a trusted vendor yet exhibits malicious behavior. This is the classic definition of signed malware, where the digital certificate used to sign the file has likely been stolen, misused, or issued fraudulently. The trusted signature bypasses reputation-based and allowlist controls, making the threat particularly dangerous because the file appears legitimate to security tools that trust the vendor's certificate.
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 Trojan horse disguised as legitimate software.
Why it's wrong here
Trojans are malware that appear legitimate but may not be signed; the distinguishing factor here is the valid signature.
- ✓
Signed malware, indicating the certificate may have been compromised.
Why this is correct
The file has a trusted digital signature but performs malicious actions, suggesting the signing key was stolen or misused.
- ✗
A zero-day exploit targeting an unpatched vulnerability.
Why it's wrong here
The file's behavior is malicious, but the key aspect is its legitimate digital signature; zero-day focuses on unknown vulnerabilities.
- ✗
A fileless attack that never writes to disk.
Why it's wrong here
Fileless attacks reside in memory; this scenario involves a file with a digital signature.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This CISA practice question is part of Courseiva's free ISACA 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 CISA exam.