The answer is to isolate the jump box from the network immediately and conduct a forensic analysis. This is correct because the high-frequency failed SSH attempts with non-existent usernames from a hardened jump box indicate it has been compromised and is being used as an attack launch point, even if antivirus shows clean—containment is the first priority in incident response to prevent lateral movement and preserve evidence. On the CISSP exam, this scenario tests your understanding of the incident response lifecycle, specifically the containment phase, and the common trap is to waste time patching or scanning when the host is already an active threat. Remember the mnemonic “ICF” for Incident response: Isolate, Contain, Forensics—never skip straight to remediation when a jump box shows automated brute-force behavior.
CISSP Security Operations Practice Question
This CISSP practice question tests your understanding of security operations. Examine the command output carefully: the correct answer depends on what the output actually shows, not on general recall alone. 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.
You are a security analyst at a financial institution. The company has a hybrid infrastructure with on-premises servers and AWS cloud. The on-premises network uses a SIEM that aggregates logs from all sources. Recently, the SIEM has been generating a high volume of alerts for failed SSH login attempts from an internal IP (10.10.50.100) to multiple Linux servers. The IP belongs to a jump box used by system administrators. Upon investigation, you find that the jump box is running a hardened OS, and only authorized admins can access it via SSH key authentication. However, the failed login attempts show usernames like 'root', 'admin', 'test', which are not valid accounts on the target servers. The attempts occur every 5 seconds around the clock. There are no successful logins from that IP. The jump box has the latest patches and antivirus. What should you do FIRST?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
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.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Isolate the jump box from the network immediately and conduct a forensic analysis
The jump box is exhibiting automated, high-frequency failed login attempts with non-existent usernames, which is a classic indicator of a compromised host being used as an attack launch point—even if the OS appears hardened and AV shows clean. The first priority in incident response is containment; isolating the jump box prevents further potential lateral movement or data exfiltration while preserving forensic evidence. A forensic analysis is then required to determine the root cause (e.g., a hidden backdoor, credential theft, or kernel-level rootkit) before any remediation steps.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
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 the usernames 'root', 'admin', 'test' to the target servers' password blacklist
Why it's wrong here
This does not address the source; the attacker could use other usernames.
✓
Isolate the jump box from the network immediately and conduct a forensic analysis
Why this is correct
The jump box is likely compromised; isolating it stops the attack and allows for investigation.
Clue confirmation
The clue word "first" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
Ignore the alerts because the usernames are invalid and the jump box is hardened
Why it's wrong here
Ignoring could allow the attacker to eventually compromise a server if they find a valid username.
✗
Run a full antivirus scan on the jump box and check for malware
Why it's wrong here
Scanning is important but containment should come first to prevent further damage.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates focus on the 'hardened OS' and 'no successful logins' as signs of safety, but CISSP expects you to recognize that anomalous outbound attack traffic from an internal asset is a containment trigger, not a false positive.
Detailed technical explanation
How to think about this question
Under the hood, SSH authentication logs (auth.log or /var/log/secure) record each attempt with source IP, username, and result; the pattern of attempts every 5 seconds with common usernames suggests an automated tool (e.g., Hydra, Medusa, or a custom script) rather than a human admin. Even if the jump box has no successful SSH logins, an attacker could have gained access via a different vector (e.g., a vulnerable web service, SSH key compromise, or supply-chain attack) and is now using the jump box as a pivot point to probe internal Linux servers. In real-world incidents, such as the 2020 SolarWinds breach, compromised jump boxes were used for lateral movement while appearing fully patched and AV-clean, emphasizing the need for immediate isolation and deep forensic analysis.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
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
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A developer is choosing between AES-256 (symmetric) and RSA-2048 (asymmetric) for encrypting a large file that will be sent to a partner. Symmetric encryption is fast but requires key exchange; asymmetric is slower but solves the key distribution problem. A hybrid approach — encrypt the file with AES, encrypt the AES key with RSA — is standard. Questions like this test whether you understand when each approach applies.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this CISSP question in full detail.
Security Operations — This question tests Security Operations — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Isolate the jump box from the network immediately and conduct a forensic analysis — The jump box is exhibiting automated, high-frequency failed login attempts with non-existent usernames, which is a classic indicator of a compromised host being used as an attack launch point—even if the OS appears hardened and AV shows clean. The first priority in incident response is containment; isolating the jump box prevents further potential lateral movement or data exfiltration while preserving forensic evidence. A forensic analysis is then required to determine the root cause (e.g., a hidden backdoor, credential theft, or kernel-level rootkit) before any remediation steps.
What should I do if I get this CISSP question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Are there clue words in this question I should notice?
Yes — watch for: "first". Order matters here. You are being tested on which action comes before the others — not which action is generally useful.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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