The correct answer is to investigate sign-in logs, MFA results, device details, and mailbox audit events first. This is because an impossible travel detection—a user authenticating from London and Singapore within 12 minutes—strongly indicates credential theft or token replay, and the subsequent mailbox forwarding rule creation signals a data exfiltration attempt. Correlating sign-in logs verifies source IPs and timestamps, MFA results reveal whether authentication was bypassed, device details confirm if a managed device was used, and mailbox audit events identify who created the rule. On the CompTIA CySA+ CS0-003 exam, this scenario tests your ability to prioritize evidence sources during a UEBA investigation, often appearing as a multi-step analysis question. A common trap is jumping to the forwarding rule alone, but the impossible travel anomaly is the primary red flag. Remember the mnemonic “SLAM” for the four evidence sources: Sign-in logs, Location (IP), Authentication (MFA), and Mailbox audit.
CS0-003 Security Operations Practice Question
This CS0-003 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. A key principle to apply: sign-in logs record user authentication attempts and details.. 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.
A UEBA rule flags a user authenticating from London and Singapore within 12 minutes, followed by a mailbox forwarding rule creation. What should the analyst investigate first? In the evidence source phase, Which evidence source best supports or refutes the detection?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "best"
Why it matters: Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
Clue: "first"
Why it matters: Order matters here. You are being tested on which action comes before the others — not which action is generally useful.
Why wrong: Browser cache is not the authoritative source for sign-in and mailbox-rule activity.
B
Sign-in logs, MFA result, device details, and mailbox audit events
Impossible travel plus forwarding rule creation is a strong account-compromise pattern; identity and mailbox audit data confirm whether the activity is malicious.
C
Only DHCP logs from the London office
Why wrong: DHCP logs cannot explain the remote sign-in or mailbox change.
D
The organisation's public DNS zone file
Why wrong: DNS zone data is unrelated to mailbox-forwarding abuse.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Sign-in logs, MFA result, device details, and mailbox audit events
Option B is correct because the detection of a user authenticating from geographically distant locations within 12 minutes strongly suggests credential theft or token replay, and the subsequent mailbox forwarding rule creation indicates a data exfiltration attempt. The analyst must first correlate sign-in logs (to verify the source IPs and timestamps), MFA results (to check if MFA was satisfied or bypassed), device details (to identify if a known or managed device was used), and mailbox audit events (to confirm who created the forwarding rule and when). This combination directly validates or refutes the UEBA alert by providing the evidence needed to distinguish between a legitimate user with a VPN or a compromised account.
Key principle: Sign-in logs record user authentication attempts and details.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
Only the user's browser cache
Why it's wrong here
Browser cache is not the authoritative source for sign-in and mailbox-rule activity.
✓
Sign-in logs, MFA result, device details, and mailbox audit events
Why this is correct
Impossible travel plus forwarding rule creation is a strong account-compromise pattern; identity and mailbox audit data confirm whether the activity is malicious.
Clue confirmation
The clue words "best", "first" in the question point toward this answer.
Related concept
Sign-in logs record user authentication attempts and details.
✗
Only DHCP logs from the London office
Why it's wrong here
DHCP logs cannot explain the remote sign-in or mailbox change.
✗
The organisation's public DNS zone file
Why it's wrong here
DNS zone data is unrelated to mailbox-forwarding abuse.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Cisco often tests the misconception that a single log source (like DHCP or browser cache) is sufficient to investigate impossible travel and mailbox rule changes, when in reality multiple correlated evidence sources (sign-in logs, MFA, device details, and audit events) are required to confirm or refute the alert.
Detailed technical explanation
How to think about this question
UEBA rules often use a time-distance heuristic (e.g., impossible travel) based on sign-in log timestamps and IP geolocation databases. The 12-minute window between London and Singapore logins exceeds physical travel limits (flight time >12 hours), so the analyst must check if the second login used a VPN, a proxy, or a token replay attack. Mailbox audit events (e.g., Set-Mailbox -ForwardingSmtpAddress) are logged in Exchange Online and can reveal the exact cmdlet, client application, and user agent used, which helps differentiate between a user's legitimate action and an attacker's automated script.
KKey Concepts to Remember
Sign-in logs record user authentication attempts and details.
MFA results indicate multi-factor authentication success or failure.
Device details link authentication to specific endpoints.
Mailbox audit events track changes to mailbox configurations, including forwarding rules.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Sign-in logs record user authentication attempts and details.
Real-world example
How this comes up in practice
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. Sign-in logs record user authentication attempts and details. Security exam questions test whether you can match controls to threats in context — not just recall definitions.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this CS0-003 question in full detail.
Review sign-in logs record user authentication attempts and details., then practise related CS0-003 questions on the same topic to reinforce the concept.
Security Operations — This question tests Security Operations — Sign-in logs record user authentication attempts and details..
What is the correct answer to this question?
The correct answer is: Sign-in logs, MFA result, device details, and mailbox audit events — Option B is correct because the detection of a user authenticating from geographically distant locations within 12 minutes strongly suggests credential theft or token replay, and the subsequent mailbox forwarding rule creation indicates a data exfiltration attempt. The analyst must first correlate sign-in logs (to verify the source IPs and timestamps), MFA results (to check if MFA was satisfied or bypassed), device details (to identify if a known or managed device was used), and mailbox audit events (to confirm who created the forwarding rule and when). This combination directly validates or refutes the UEBA alert by providing the evidence needed to distinguish between a legitimate user with a VPN or a compromised account.
What should I do if I get this CS0-003 question wrong?
Review sign-in logs record user authentication attempts and details., then practise related CS0-003 questions on the same topic to reinforce the concept.
Are there clue words in this question I should notice?
Yes — watch for: "best", "first". Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
What is the key concept behind this question?
Sign-in logs record user authentication attempts and details.
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These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A UEBA rule flags a user authenticating from London and Singapore within 12 minutes, followed by a mailbox forwarding rule creation. What should the analyst investigate first? In the alert triage phase, Which action gives the analyst the clearest next triage step?
Why C: Option C is correct because the alert indicates a potential account compromise (impossible travel from London to Singapore in 12 minutes) followed by a suspicious mailbox rule creation. The clearest next triage step is to examine sign-in logs for authentication source IPs and timestamps, MFA result to verify if the second factor was passed, device details to check for known or managed devices, and mailbox audit events to confirm who created the forwarding rule and when. This combination directly validates whether the user's credentials were used from two geographically impossible locations and whether the mailbox rule was created by the legitimate user or an attacker.
Variation 2. A UEBA rule flags a user authenticating from London and Singapore within 12 minutes, followed by a mailbox forwarding rule creation. What should the analyst investigate first? In the containment trade-off phase, Which response balances containment with evidence preservation?
Why A: Option A is correct because the UEBA rule indicates a possible account compromise (impossible travel followed by mailbox rule creation). The analyst must first verify the sign-in logs for authentication source IPs, MFA result to check if the attacker bypassed MFA, device details to identify if a known device was used, and mailbox audit events to confirm the forwarding rule. These four data sources provide the minimum evidence needed to assess the scope of compromise before containment.
Variation 3. A UEBA rule flags a user authenticating from London and Singapore within 12 minutes, followed by a mailbox forwarding rule creation. What should the analyst investigate first? In the detection engineering phase, Which detection or tuning approach would reduce noise without losing the signal?
Why D: Option D is correct because the scenario describes a potential account takeover or lateral movement, where an impossible travel event (logins from London and Singapore within 12 minutes) is followed by a suspicious mailbox forwarding rule. The analyst must first verify the sign-in logs for authentication details, MFA results to check if the MFA was bypassed or prompted, device details to identify if a known or managed device was used, and mailbox audit events to confirm the forwarding rule creation and its origin. These combined data sources provide the most direct evidence to determine if the activity is malicious or a false positive.
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