Maria most likely used fileless malware, because the scenario explicitly describes malicious activity that does not write a payload executable to disk and instead executes entirely in memory using PowerShell and process injection. In CEH-aligned malware classifications, fileless malware is characterized by leveraging legitimate system tools (often called "living off the land" utilities) such as PowerShell, WMI, cmd.exe, or scripting engines to execute attacker-controlled code without creating traditional malware files on the filesystem. Since many legacy antivirus solutions depend heavily on signature-based scanning of files on disk, purely memory- resident execution can reduce or eliminate typical AV detections and leave minimal artifacts in standard AV logs.
The description also mentions that after a reboot the system returns to normal, which strongly supports fileless behavior: if the attacker did not establish persistence (for example via registry run keys, scheduled tasks, services, or WMI event subscriptions), then the in-memory code and injected instructions would be cleared when memory is reset. The "abnormal spikes in resource usage" are consistent with malicious scripts running inside a trusted process context, where attackers may inject or reflectively load code to blend into normal operating activity and evade straightforward monitoring.
Why the other options are incorrect: a rootkit primarily focuses on stealth through deep system-level hiding (often kernel/driver-level) and is commonly associated with persistent concealment rather than "no disk footprint" PowerShell-only execution. A trojan is typically a malicious program masquerading as legitimate software and usually involves a delivered executable or application. Ransomware is defined by encrypting data and extorting payment, which is not described here.
Thus, the technique most consistent with the test is fileless malware executed via PowerShell and memory- only injection.

The correct answer is RSA. CEH cryptography coverage describes RSA as a widely used asymmetric algorithm that supports encryption and digital signatures and is commonly deployed in public-key infrastructures. The question states that the transaction data is hashed, the hash is signed with the sender's private key, and the recipient verifies the signature with the matching public key. That is the classic RSA signature model presented in CEH materials. The additional clue is that the same algorithm is said to support encryption, digital signatures, and secure communications use cases. Diffie-Hellman is mainly a key exchange mechanism and is not used for digital signatures in the way described here. DSA is designed for digital signatures, but not for general encryption. ElGamal can support encryption and signatures, but CEH exam framing most strongly associates this full combination of encryption plus digital-signature verification with RSA. CEH references repeatedly emphasize RSA as the standard asymmetric cryptosystem for confidentiality, authentication, integrity, and nonrepudiation in enterprise communications. Because the described implementation combines hashing, private-key signing, and public-key verification within a broad asymmetric framework, RSA is the most accurate answer.

The scenario points to a JavaScript-based keylogger because the data capture occurs entirely within a web page and does not require installing software on the victim's machine. In CEH-aligned social engineering and web attack concepts, phishing pages commonly include client-side scripts that capture form inputs in real time. When a user types credentials into a fake login form, JavaScript event handlers can record keystrokes or the final field values and transmit them to an attacker-controlled endpoint. This explains why Tyler's
"payload" works without local privilege, without dropping executables, and without triggering traditional antivirus focused on file-based malware. The key detail is that "captured keystrokes came exclusively from a web-based form embedded in the fake login page," which matches browser-based capture rather than OS- level logging.
The other options imply deeper system access than the prompt describes. A keyboard keylogger typically operates at the operating-system level by intercepting keyboard input system-wide, which usually requires running code on the host and is more likely to be detected by endpoint protections. A hypervisor-based keylogger is a highly advanced technique that relies on virtualization-layer control and is not consistent with a simple phishing web page. An application keylogger usually targets specific processes on the endpoint (such as browsers or email clients), again requiring execution on the local machine.
From a defensive viewpoint emphasized in CEH, mitigations include user awareness training to spot phishing pages, enforcing MFA to reduce the value of stolen credentials, using anti-phishing protections and URL filtering, monitoring for lookalike domains, and deploying browser and email security controls that detect credential-harvesting pages and suspicious form-post destinations.

The scenario emphasizes that Daniel "begins capturing and reviewing live network traffic" to identify unauthorized session behaviors. In CEH-aligned network analysis practice, the most direct method to confirm session hijacking when you already have a packet capture is manual packet analysis using packet sniffing tools. By inspecting live traffic, Daniel can correlate sessions, verify whether multiple sources are reusing the same session identifiers, identify abnormal TCP sequence and acknowledgment behavior, and detect patterns such as duplicated cookies/tokens, replayed requests, inconsistent client IP or user-agent shifts, or sudden session reuse across hosts. This approach provides evidentiary detail beyond an alert and allows validation before escalation.
An IDS can be helpful, but it is a detection system that generates alerts based on signatures or anomalies; it does not inherently "confirm" the issue unless it provides clear supporting evidence, and the question specifically frames Daniel's action as hands-on traffic review. Checking for predictable session tokens is a preventive and diagnostic step for weak session management design, but it does not directly confirm an in- progress hijacking event from observed network behavior. Monitoring for ACK storms can indicate certain TCP-level hijacking/desynchronization conditions, but it is narrower and may not apply to application-layer session hijacking, which is far more common in enterprise environments and would be validated by inspecting session identifiers and request flows in the capture.
Therefore, given the described workflow and the need to confirm unauthorized session activity from live traffic, CEH methodology aligns best with manual packet analysis using sniffing tools.

SMTP enumeration is the correct classification because the scenario explicitly references the SMTP commands VRFY, EXPN, and RCPT, which are well-known techniques for discovering valid user accounts and email routing information on mail servers. In CEH-aligned enumeration methodology, attackers and testers use these commands to determine whether specific usernames or mailbox addresses exist. VRFY is used to verify a user, EXPN can expand a mailing list or alias into individual recipients, and RCPT TO is commonly tested during an SMTP conversation to see whether a recipient address is accepted or rejected.
When a server provides detailed responses, it can leak account validity and internal addressing formats, enabling targeted phishing, password spraying against known usernames, and broader social engineering campaigns.
Although the assessment also identifies Telnet, FTP with anonymous access, TFTP, and SMB shares, those findings represent additional exposed services and misconfigurations rather than the named enumeration classification in the answer choices. LDAP enumeration would focus on directory queries against services such as LDAP or Active Directory to extract users and groups. VoIP enumeration would involve SIP endpoints, extensions, and call infrastructure. DNS enumeration would center on zone transfers, record harvesting, and subdomain discovery. The distinguishing clue here is the use of VRFY, EXPN, and RCPT, which is uniquely tied to SMTP behavior and mail server user enumeration, making SMTP Enumeration the best fit.