Question 595 of 1,013
Fileless Attack Indicators: PowerShell Encoded Command and Memory Execution
A SOC analyst reviews an EDR alert on a finance workstation. The alert shows powershell.exe launched with an encoded command, downloaded a payload into memory, and then spawned rundll32.exe. No new executable was written to disk, but the process later created a scheduled task for persistence. Which two findings most strongly support a fileless attack? Select two.
Quick Answer
The answer is the PowerShell encoded command and the in-memory execution of the payload, as these are the two strongest fileless attack indicators. Fileless attacks rely on living-off-the-land binaries like PowerShell to run malicious code directly in RAM, bypassing traditional disk-based antivirus scans. In this scenario, the encoded command allowed the attacker to obfuscate the script, while downloading and executing the payload entirely in memory avoided writing any malicious executable to disk—a core hallmark of fileless malware. On the Security+ SY0-701 exam, this tests your ability to distinguish fileless techniques from standard malware, which typically leaves a file on disk. A common trap is focusing on the scheduled task, but that is a persistence mechanism, not the attack vector itself. Remember the mnemonic "No Disk, No Risk"—if no new executable hits the disk, suspect fileless execution.
⚠ Common exam trap
Candidates often confuse fileless attacks with any attack that uses PowerShell or scripting, but the key distinction is the absence of writing any executable to disk, which is why options involving disk writes or signature-based quarantine are distractors.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
powershell.exe launched with an encoded command and executed the payload in memory
Executing a PowerShell encoded command that downloads and runs a payload entirely in memory, without writing to disk, is a hallmark of fileless malware. This technique avoids traditional file-based detection by leveraging PowerShell's ability to load and execute scripts directly in memory, bypassing disk-based antivirus scans.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
powershell.exe launched with an encoded command and executed the payload in memory
Why this is correct
Encoded PowerShell is a common fileless technique because the malicious instructions can be hidden inside a command line and run directly in memory. This reduces obvious disk artifacts and can bypass simple file-based detection. In a Security+ scenario, that combination strongly suggests living-off-the-land abuse rather than a traditional dropped executable.
- ✓
rundll32.exe was spawned by a script-based process during the attack chain
Why this is correct
rundll32.exe is a legitimate Windows binary that attackers often abuse to execute code without introducing a custom executable. When it is launched by a scripting process during suspicious activity, it supports a fileless or living-off-the-land pattern. The process chain matters because it shows trusted tools being repurposed for execution.
- ✗
a new portable executable was written to the user's temporary folder before being run
Why it's wrong here
A new executable dropped to disk is more consistent with traditional malware delivery than fileless execution. Fileless attacks try to minimize or avoid creating obvious files on the system. This option describes a disk-based artifact, which weakens the case for a fileless technique.
- ✗
the endpoint antivirus quarantined the payload after a signature match
Why it's wrong here
Antivirus quarantine shows the security tool detected something suspicious, but it does not by itself indicate a fileless attack. A signature match could happen with many malware types. This is a response action, not a behavioral indicator of how the attacker executed code.
- ✗
a USB storage device was inserted shortly before the alert fired
Why it's wrong here
Removable media can be used to deliver malware, but that detail alone does not point to fileless execution. The alert already shows in-memory PowerShell and trusted binary abuse, which are much stronger indicators. USB insertion is possible context, but it is not the key fileless clue here.
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Same concept, more angles
5 more ways this is tested on SY0-701
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 security analyst receives an alert from the email security gateway about a message sent to an employee. The email has an attachment named 'Invoice_Q4_2024.exe'. The employee claims they did not open the attachment, and the email appears to come from a known vendor's domain but the sender address has a slight typo. Which type of attack is most likely being attempted?
medium- ✓ A.Spear phishing
- B.Phishing
- C.Smishing
- D.Vishing
Why A: The email is targeted at a specific employee and impersonates a known vendor to exploit a trusted business relationship. The use of a domain typo (domain spoofing) is a common spear phishing technique to trick the recipient into executing malware. While the lure ('Invoice_Q4_2024.exe') is not highly personalized, the impersonation of a known vendor constitutes targeting a specific organization, making spear phishing more likely than broad, unsolicited phishing.
Variation 2. A SOC analyst reviews an alert on a workstation where PowerShell launched from a scheduled task, downloaded an encoded command from a remote server, and then spawned rundll32.exe. Traditional antivirus did not flag any files on disk, and the activity stops after rebooting the host. Which type of malware behavior best fits this event?
medium- A.Worm behavior that is spreading through SMB shares
- ✓ B.Fileless attack using trusted system tools to run malicious code in memory
- C.Rootkit that is hiding itself by modifying kernel drivers
- D.Trojan that can only run after a user manually opens a malicious attachment
Why B: The attack uses PowerShell to download and execute an encoded command directly in memory, then spawns rundll32.exe—both are trusted Microsoft binaries. No files are written to disk, and the activity ceases after reboot, which are hallmarks of a fileless malware attack that operates entirely in volatile memory.
Variation 3. A SOC analyst reviews an EDR alert on a Windows workstation. PowerShell was launched by a scheduled task, downloaded an encoded command from an external server, and then spawned rundll32.exe. No suspicious executable was written to disk. Which type of threat best fits this activity?
medium- A.Trojan
- ✓ B.Fileless attack
- C.Rootkit
- D.Worm
Why B: The attack is fileless because it executes entirely in memory without writing a malicious executable to disk. PowerShell downloads an encoded command from an external server and spawns rundll32.exe to run code via DLL execution, leveraging living-off-the-land binaries (LOLBins) to evade traditional antivirus and disk-based detection.
Variation 4. An EDR alert shows powershell.exe launching with an encoded command, no new executable written to disk, and a registry run key added for persistence. Outbound HTTPS traffic then begins to a rare external domain. Which type of malware behavior is most likely?
medium- A.Worm behavior, because the malware is automatically spreading across the network.
- ✓ B.Fileless attack, because the malicious activity is using legitimate tools and memory rather than a dropped payload.
- C.Rootkit behavior, because the attacker is hiding from the operating system at a low level.
- D.Spyware, because the malware is using HTTPS traffic to contact an external domain.
Why B: The EDR alert describes a classic fileless attack: PowerShell.exe executes an encoded command in memory, no new executable is written to disk, and persistence is achieved via a registry run key. The outbound HTTPS traffic to a rare domain indicates command-and-control (C2) communication. Fileless malware leverages legitimate system tools (like PowerShell) and runs entirely in memory, bypassing traditional file-based detection.
Variation 5. An EDR alert shows PowerShell launching from a scheduled task, downloading encoded commands, and running them in memory. No suspicious executable is written to disk. What kind of attack is this?
easy- ✓ A.A fileless attack that relies on trusted tools already on the system
- B.A worm that spreads by exploiting a network service
- C.A logic bomb that waits for a specific date or event
- D.A rootkit that changes kernel behavior to hide processes
Why A: This is a fileless attack because PowerShell, a trusted system tool, is used to download and execute encoded commands directly in memory without writing any malicious executable to disk. The attack leverages living-off-the-land binaries (LOLBins) and PowerShell's ability to run scripts in memory, bypassing traditional file-based detection mechanisms.
Last reviewed: Jun 11, 2026
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