CompTIA CAS-004 Exam

The SIEM logs indicate suspicious behavior that could be a sign of a compromise, such as the launching of cmd.exe after Outlook.exe, which is atypical user behavior and could indicate that a machine has been compromised to perform lateral movement within the network. Isolating laptop314 from the network would contain the threat and prevent any potential spread to other systems while further investigation takes place.

Using digital certificates for authentication is a secure method to control access to laptops and other devices. A device certificate can serve as an authenticator by providing a means for the device to prove its identity in a cryptographic manner. This certificate-based authentication is commonly used in enterprise environments for strong authentication.

Calculating the Annual Loss Expectancy (ALE) and conducting a cost-benefit analysis is a critical part of risk management. The ALE will help the company understand the potential losses associated with the server failure per year, which can then be weighed against the cost of mitigating the risk (e.g., replacing the server or implementing redundancies). This analysis will inform the decision on the best course of action to manage the risk associated with the aging server.

Input validation is a technique that checks the user input for any errors, malicious data, or unexpected values before processing it by the application. Input validation can prevent many common web application attacks, such as:

SQL injection, which exploits a vulnerability in the application's database query to execute malicious SQL commands.

Cross-site scripting (XSS), which injects malicious JavaScript code into the application's web page to execute on the client-side browser.

Directory traversal, which accesses files or directories outside of the intended scope by manipulating the file path.

In this case, the security engineer should recommend input validation as the best mitigation technique, because it would:

Prevent the exfiltration of a company report by validating the file parameter in the URL and ensuring that it matches a predefined list of allowed files or formats.

Enhance the security of the web application by filtering out any malicious or invalid input from users or attackers.

Be more effective and efficient than other techniques, such as firewall, WAF (Web Application Firewall), or DLP (Data Loss Prevention), which may not be able to detect or block all types of web application attacks.

Based on the SIEM alerts, the security analyst should first disable the jdoe account, as it is likely compromised by an attacker. The alerts show that the jdoe account successfully logged on to the abc-usa-fsl server, which is a file server, and then initiated SMB (445) traffic to the abc-web01 server, which is a web server. This indicates that the attacker may be trying to exfiltrate data from the file server to the web server. Disabling the jdoe account would help stop this unauthorized activity and prevent further damage.

Disabling Administrator on abc-usa-fsl, the local account is compromised, is not the first action to take, as it is not clear from the alerts if the local account is compromised or not. The alert shows that there was a successful logon event for Administrator on abc-usa-fsl, but it does not specify if it was a local or domain account, or if it was authorized or not. Moreover, disabling the local account would not stop the SMB traffic from jdoe to abc-web01.

Shutting down the abc-usa-fsl server, a plaintext credential is being used, is not the first action to take, as it is not clear from the alerts if a plaintext credential is being used or not. The alert shows that there was RDP (3389) traffic from abc-admin1-logon to abc-usa-fsl, but it does not specify if the credential was encrypted or not. Moreover, shutting down the file server would disrupt its normal operations and affect other users.

Shutting down abc-usa-fw01; the remote access VPN vulnerability is exploited, is not the first action to take, as it is not clear from the alerts if the remote access VPN vulnerability is exploited or not. The alert shows that there was FTP (21) traffic from abc-usa-dcl to abc-web01, but it does not specify if it was related to the VPN or not. Moreover, shutting down the firewall would expose the network to other threats and affect other services.Reference:What is SIEM? | Microsoft Security, What is a SIEM Alert? | Cofense