CompTIA Updated PT0-003 Exam Questions and Answers by tessa

Comprehensive and Detailed Explanation:

A reverse shell that is left on a target to maintain access is a form of persistence/backdoor. The action described — removing the reverse shell at the end of the engagement — is specifically the removal of a persistence mechanism. Post-engagement cleanup requires removal of any artifacts that provide continued access (web shells, scheduled tasks, reverse shells, cron jobs, created accounts, etc.) so the environment is returned to its pre-test state and to prevent later compromise.

Why not the others:

B (Uninstalling tools): Removing tools is also a cleanup activity, but the question explicitly references removing the reverse shell (persistence).

C (Preserving artifacts): Preserving artifacts is the opposite (saving logs/evidence) for incident response — not removing access.

D (Reverting configuration changes): Important, but the best single match for removing a reverse shell is “removing persistence mechanisms.”

PT0-003 mapping: Domain 5 — post-engagement cleanup and returning environment to baseline.

By default, Nmap scans the top 1,000 most commonly used TCP ports unless otherwise specified.

Option A (256) ❌: Incorrect. This refers to the number of hosts in a /24 subnet, not the number of ports scanned.

Option B (1,000) ✅: Correct. Nmap defaults to scanning the 1,000 most common TCP ports unless the -p flag is used to specify a different range.

Option C (1,024) ❌: Incorrect. The first 1,024 ports are well-known ports, but Nmap scans 1,000 by default, not 1,024.

Option D (65,535) ❌: Incorrect. Nmap only scans all ports if the -p- flag is used (e.g., nmap -p- ).

???? Reference: CompTIA PenTest+ PT0-003 Official Guide – Network Scanning with Nmap

To maintain access to a compromised system after rebooting, a penetration tester should create a scheduled task. Scheduled tasks are designed to run automatically at specified times or when certain conditions are met, ensuring persistence across reboots.

Persistence Mechanisms:

Scheduled Task: Creating a scheduled task ensures that a specific program or script runs automatically according to a set schedule or in response to certain events, including system startup. This makes it a reliable method for maintaining access after a system reboot.

Reverse Shell: While establishing a reverse shell provides immediate access, it typically does not survive a system reboot unless coupled with another persistence mechanism.

Process Injection: Injecting a malicious process into another running process can provide stealthy access but may not persist through reboots.

Credential Dumping: Dumping credentials allows for re-access by using stolen credentials, but it does not ensure automatic access upon reboot.

Creating a Scheduled Task:

On Windows, the schtasks command can be used to create scheduled tasks. For example:

schtasks /create /tn "Persistence" /tr "C:\path\to\malicious.exe" /sc onlogon /ru SYSTEM

On Linux, a cron job can be created by editing the crontab:

(crontab -l; echo "@reboot /path/to/malicious.sh") | crontab -

Pentest References:

Maintaining persistence is a key objective in post-exploitation. Scheduled tasks (Windows Task Scheduler) and cron jobs (Linux) are commonly used techniques.

References to real-world scenarios include creating scheduled tasks to execute malware, keyloggers, or reverse shells automatically on system startup.

By creating a scheduled task, the penetration tester ensures that their access method (e.g., reverse shell, malware) is executed automatically whenever the system reboots, providing reliable persistence.

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The smbclient tool is used to access SMB/CIFS resources on a network. It allows penetration testers to connect to shared resources and enumerate users on a network, particularly in Windows environments. While finger and rwho are more common on Unix/Linux systems, smbclient provides better functionality for enumerating users across a network.

Understanding smbclient:

Purpose: smbclient is used to access and manage files and directories on SMB/CIFS servers.

Capabilities: It allows for browsing shared resources, listing directories, downloading and uploading files, and enumerating users.

User Enumeration:

Command: Use smbclient with the -L option to list available shares and users.

Step-by-Step Explanationsmbclient -L //target_ip -U username

Example: Enumerating users on a target system.

smbclient -L //192.168.50.2 -U anonymous

Advantages:

Comprehensive: Provides detailed information about shared resources and users.

Cross-Platform: Can be used on both Linux and Windows systems.

References from Pentesting Literature:

SMB enumeration is a common practice discussed in penetration testing guides for identifying shared resources and users in a network environment.

HTB write-ups frequently mention the use of smbclient for enumerating network shares and users.