CS0-003 Practice Test 3 — 25 Questions

Question 1

A security analyst is reviewing alerts from an IDS. Which TWO indicators are most likely to suggest a successful command and control (C2) communication? (Choose two.)

Accepted Answer

A high volume of outbound traffic to an unusual destination IP on port 443. Option B is correct because sustained outbound traffic to an unusual external IP over port 443 is a classic C2 indicator: attackers frequently tunnel C2 over HTTPS (TCP 443) to blend with legitimate web traffic, and the destination being atypical for the environment raises suspicion. Option E is correct because regular beaconing to an external IP with consistent payload sizes reflects the periodic check-in pattern used by implants (e.g., fixed intervals with jitter and uniform packet sizes), which is a hallmark of established C2 channels. Option A does not belong because an inbound connection from a malicious IP to a mail server suggests scanning, exploitation, or spam relay activity rather than an internal host initiating C2. Option C does not belong because a single large upload to cloud storage is more indicative of data exfiltration than C2, and cloud storage is a legitimate service. Option D does not belong because a DNS query for a malicious domain indicates possible resolution or attempted contact, but a single query alone does not demonstrate the sustained, bidirectional communication characteristic of successful C2.

Answer

An inbound connection from a known malicious IP to the mail server

Answer

A single large file upload to a cloud storage service

Answer

An internal host performing a DNS query for a known malicious domain

Question 2

An analyst needs to identify which process on a Windows system is making outbound connections to the internet. Which tool should be used?

Accepted Answer

Resource Monitor. Resource Monitor (resmon.exe) provides a real-time view of network activity, including which processes are making outbound TCP and UDP connections, along with the remote addresses and ports. Unlike netstat, it directly associates network connections with specific process names and allows filtering by process, making it the most efficient tool for identifying the exact process responsible for outbound internet traffic.

Answer

netstat -an

Answer

Task Manager

Answer

Performance Monitor

Question 3

A security analyst is reviewing a report from an authenticated vulnerability scan of a Windows domain controller. The report indicates multiple critical vulnerabilities related to Active Directory. The system administrator claims the patches have been applied. Which of the following is the MOST likely cause of the discrepancy?

Accepted Answer

The patches require a reboot. The most likely cause is that the patches require a reboot. Many critical Active Directory vulnerabilities, such as those in Kerberos or LSASS, are mitigated by patches that only take effect after a system restart. The authenticated scan detects the vulnerability because the patched files are not yet loaded into memory, even though the patches are installed on disk.

Answer

The vulnerabilities are false positives

Answer

The scan was run with insufficient credentials

Answer

The scan was run before patch installation

Question 4

A security analyst at a financial institution is responsible for vulnerability management. The company has a policy that all critical vulnerabilities must be remediated within 72 hours. The weekly vulnerability scan identifies a critical vulnerability on a file server that hosts sensitive customer data. The vulnerability is a remote code execution in the operating system. The server is running a legacy OS that is no longer supported by the vendor. The system owner states that the application on the server cannot be migrated to a newer OS for at least six months. The server cannot be taken offline because it is used by the compliance team for daily audits. Which of the following should the analyst recommend to best address the risk?

Accepted Answer

Implement compensating controls such as network segmentation and host-based firewall rules.. When a critical vulnerability cannot be patched due to legacy OS constraints, compensating controls are the best approach to reduce risk. Network segmentation isolates the server from untrusted hosts, and host-based firewall rules restrict inbound/outbound traffic to only necessary ports and IPs, mitigating the remote code execution vector without taking the server offline.

Answer

Remove the server from the network immediately.

Answer

Accept the risk and document the exception.

Answer

Apply a custom patch developed by the manufacturer.

Question 5

An EDR alert shows powershell.exe launched by winword.exe with an encoded command line and outbound HTTPS shortly after a user opened an email attachment. What is the BEST first analytic pivot? In the alert triage phase, Which action gives the analyst the clearest next triage step?

Accepted Answer

Decode the command and inspect the process tree, parent document, and network destination. Decoding the encoded PowerShell command reveals the attacker's intent, inspecting the process tree shows the execution chain from winword.exe to powershell.exe, examining the parent document identifies the malicious attachment, and analyzing the network destination uncovers the C2 server. This systematic approach provides the clearest next triage step by correlating the initial infection vector with the subsequent malicious activity, enabling the analyst to contain the threat effectively.

Answer

Disable the SIEM parser for PowerShell events

Answer

Reimage every workstation in the department

Answer

Close the alert because HTTPS is expected traffic

Question 6

A SOC analyst notices a spike in outbound traffic from a server that normally only serves web pages. The signature-based IDS did not alert. What should the analyst do next?

Accepted Answer

Query threat intelligence for the destination IPs. Querying threat intelligence for the destination IPs is the correct next step because the spike in outbound traffic from a web server suggests a potential data exfiltration attempt or command-and-control (C2) communication. Since the signature-based IDS did not alert, the traffic may be using non-standard ports or encrypted channels that evade known signatures. Threat intelligence can reveal if the destination IPs are associated with known malicious actors, botnets, or recent threat campaigns, providing context to determine if the traffic is benign or malicious.

Answer

Disable the server immediately

Answer

Check for zero-day vulnerabilities

Answer

Increase the IDS sensitivity threshold

Question 7

During a containment phase of an incident response, the team needs to prevent an infected host from communicating with a command-and-control server. The host is a critical database server that cannot be taken offline. Which of the following containment strategies is most appropriate?

Accepted Answer

Block the C2 IP at the firewall. Blocking the C2 IP at the firewall is the most appropriate strategy because it disrupts the command-and-control communication without taking the critical database server offline. This network-layer containment allows the host to continue serving its database functions while preventing outbound traffic to the malicious IP, aligning with the need for a surgical containment approach.

Answer

Pull the network cable

Answer

Disable the database service

Answer

Isolate the host by VLAN

Question 8

During forensic analysis of a compromised server, the analyst finds that the attacker deleted the system logs. Which data source is most likely to still contain relevant evidence?

Accepted Answer

Endpoint detection and response (EDR) telemetry. EDR telemetry is the most reliable source because it captures process creation, network connections, file modifications, and registry changes in real-time, storing them off-host. Even if an attacker deletes local system logs, the EDR agent's telemetry stream remains intact on the central management server, providing a forensic timeline of the attacker's actions.

Answer

Memory dump from before the attack

Answer

Network flow logs

Answer

Backup tapes

Question 9

Which metric measures the average time taken to fix a vulnerability after it is identified?

Accepted Answer

Mean time to remediate (MTTRem). Mean time to remediate (MTTRem) is defined as the average elapsed time between when a vulnerability is identified and when it is fully remediated (patched, mitigated, or accepted with compensating controls). This matches the question's wording exactly — identification to fix.

Answer

Mean time to detect (MTTD)

Answer

Mean time to respond (MTTR)

Answer

Patch SLA compliance %

Question 10

A root-cause analysis finds that an alert fired but was never triaged. Which corrective actions are useful? (Choose two.)

Accepted Answer

Define queue ownership and escalation thresholds. Defining queue ownership and escalation thresholds ensures that alerts are assigned to a specific team or individual and have a clear path for escalation if not acknowledged within a defined time. This directly addresses the root cause of the alert never being triaged by enforcing accountability and automated follow-up, which is a standard incident response practice per NIST SP 800-61.

Answer

Blame an individual without process review

Answer

Delete the alert rule because it was inconvenient

Question 11

During incident response, a team isolates a host but needs to preserve volatile evidence. What should be done first?

Accepted Answer

Capture a memory dump. When a host is isolated during incident response, the first priority is to capture volatile data before it is lost. A memory dump preserves the contents of RAM, which includes running processes, network connections, open files, and encryption keys. This data is critical for forensic analysis and disappears when the system is powered off. Disconnecting the network (option B) is important but should follow memory capture because network activity is part of the volatile state.

Answer

Disconnect from the network

Answer

Reimage the hard drive

Answer

Reboot the system

Question 12

A DAST scan cannot reach authenticated pages of a web application and reports only public content findings. What should be configured? For control selection, Which control best addresses the stated weakness without hiding risk?

Accepted Answer

Authenticated scanning with a test account and session handling. DAST scanners require authenticated access to crawl and test pages behind login forms. By configuring authenticated scanning with a test account and session handling (e.g., using cookies or OAuth tokens), the scanner can traverse protected routes and detect vulnerabilities such as SQL injection or XSS on authenticated pages. This directly addresses the stated weakness without masking risk.

Answer

Disable all application authentication

Answer

Treat absence of findings as proof of security

Answer

Reduce the scan to only the landing page

Question 13

A vulnerability management team has identified a critical vulnerability with a CVSS score of 9.8. The vulnerability affects a public-facing web server that handles sensitive customer data. The team decides to apply a patch immediately without going through the normal patch testing cycle. What type of patching procedure is this?

Accepted Answer

Emergency patching. When a critical vulnerability is actively exploited or poses immediate risk, emergency patching procedures are used to expedite deployment without standard testing.

Answer

Rolling patch deployment

Answer

Patch compliance tracking

Answer

Standard patch management

Question 14

A security analyst reviews a Nessus scan result for a web server. The plugin output indicates a critical vulnerability with CVSS v3.1 base score 9.8. The CVSS vector is AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H. Which of the following best describes the attack complexity?

Accepted Answer

Low. In the CVSS vector, AC:L means Attack Complexity is Low, indicating no special conditions are required for exploitation.

Answer

Critical

Answer

Medium

Answer

High

Question 15

During a threat hunting exercise, an analyst creates a hypothesis that a threat actor may be using scheduled tasks for persistence. Which Windows registry key or log source should the analyst examine to confirm the hypothesis?

Accepted Answer

Review the Windows Security Event Log for event ID 4698 (scheduled task creation). Scheduled tasks are stored in the Windows Task Scheduler and can be viewed via schtasks.exe, but the registry also contains persistence mechanisms. However, scheduled tasks are not primarily stored in the registry; they are in %SystemRoot%\Tasks. Alternatively, the analyst can use the Task Scheduler API. But among the options, examining the 'HKLM\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Schedule' is not standard. Actually, the correct answer is to examine the Task Scheduler logs or the tasks folder. However, the question specifies registry key or log source. The best answer is to review the Windows Security Event Log for event ID 4698 (scheduled task creation).

Answer

Check the Run registry keys (HKLM\Software\Microsoft\Windows\CurrentVersion\Run)

Answer

Examine the System event log for driver loading events

Answer

Analyze the application event log for error messages

Question 16

An organization has experienced a data breach involving personal data of EU residents. Under GDPR, what is the maximum time frame within which the organization must notify the supervisory authority?

Accepted Answer

72 hours. GDPR Article 33 requires that data breaches be reported to the relevant supervisory authority within 72 hours of becoming aware of the breach, unless the breach is unlikely to result in a risk to individuals' rights and freedoms.

Answer

24 hours

Answer

7 days

Answer

48 hours

Question 17

An analyst is using AWS GuardDuty and sees a finding that an EC2 instance is communicating with a known command-and-control (C2) IP address. What type of alert is this?

Accepted Answer

Threat intelligence finding. GuardDuty detects threats based on known malicious IPs, so communication with a C2 IP is a security finding indicating a potential compromise.

Answer

CASB alert investigation

Answer

Vulnerability scan result

Answer

Cloud audit log analysis

Question 18

A SOC analyst reviews DNS telemetry and sees a workstation resolving hundreds of algorithmically generated domains at fixed intervals, with most responses returning NXDOMAIN. What evidence should the analyst prioritize to validate command-and-control beaconing? In the evidence source phase, Which evidence source best supports or refutes the detection?

Accepted Answer

Correlate DNS query logs with endpoint process and network connection telemetry. Correlating DNS query logs with endpoint process and network connection telemetry (Option D) provides direct evidence of command-and-control (C2) beaconing by linking the algorithmically generated domain (AGD) queries to a specific process initiating outbound connections. This cross-referencing validates whether the DNS activity is part of a malware's C2 channel, as legitimate applications rarely generate hundreds of NXDOMAIN responses at fixed intervals. The SOC analyst can confirm the detection by identifying the parent process (e.g., a suspicious executable) and matching its network connections to the queried domains.

Answer

Search only for successful HTTP 200 responses

Answer

Delete the host from the SIEM asset inventory

Answer

Block all DNS traffic from the subnet

Question 19

You are a senior incident responder for a large technology company. During a routine threat hunting exercise, you detect unusual network traffic from a Linux web server to an external IP address that is known to be associated with an advanced persistent threat (APT) group. The web server runs a custom PHP application and is not in the DMZ; instead, it's on the internal network serving a management dashboard. You have captured a memory dump of the web server and analyzed it with volatility. The output shows a suspicious process running with the name 'apache2' but with an invalid parent process (PID 1 is 'apache2' itself). Additionally, you find a kernel module loaded called 'hideproc.ko' that is not part of the standard kernel. The network connections show a reverse shell to the external IP. You need to determine the most effective containment and eradication strategy that minimizes data loss and maintains business continuity while preserving evidence for law enforcement involvement.

Accepted Answer

Isolate the web server from the network immediately, capture a full disk and memory image, then reimage the server from a trusted backup or OS image, and restore application data from a known clean backup.. The presence of a kernel rootkit ('hideproc.ko') and a reverse shell indicates deep, persistent compromise that cannot be cleaned by patching or scanning. Isolating the server preserves volatile evidence (memory, disk) for law enforcement, while reimaging from a trusted backup ensures complete removal of the attacker's foothold, minimizing data loss and restoring business continuity.

Answer

Revert the web server to a previous snapshot from before the suspected compromise date, then run a full antivirus scan on the restored system.

Answer

Perform a live forensic analysis of the PHP application logs and database to identify the specific vulnerability used, then apply a hotfix to the application code.

Answer

Block the external IP address at the firewall and block all outbound traffic from the web server except to specific internal IPs, then continue monitoring for other compromised hosts.

Question 20

A hospital's IT department has been receiving reports from nursing staff that the electronic medical record (EMR) system is responding slowly during peak hours. The network team has verified that the local area network is operating normally and there is no bandwidth congestion. The security analyst reviews the firewall logs and observes repeated outbound connections from the EMR server to an external IP address 198.51.100.23 on TCP port 443 at regular 5-minute intervals. Each connection transfers a small amount of data. The analyst also notes that the EMR server's antivirus software is up to date and no malware has been detected. The hospital's security policy requires that all outbound connections from critical servers be explicitly approved. Further investigation reveals that 198.51.100.23 is associated with a hosting provider in a foreign country. The analyst suspects a data exfiltration. Which of the following actions should the analyst take FIRST?

Accepted Answer

Capture and analyze the network traffic between the EMR server and the external IP.. The analyst must first confirm whether the outbound connections are actually exfiltrating data or are legitimate (e.g., software updates, license checks). Capturing and analyzing the network traffic (e.g., using tcpdump or Wireshark) allows the analyst to inspect the payload and determine the nature of the data being sent, which is a standard step in incident response before taking more disruptive actions.

Answer

Install a network-based intrusion detection system to monitor the server.

Answer

Isolate the EMR server from the network and run a full forensic analysis.

Answer

Block all outbound traffic from the EMR server to the internet immediately.