Question 253 of 509

Attacks and Exploits →hardMultiple ChoiceObjective-mapped

Quick Answer

The answer is to create a PostgreSQL function using a trusted language like Python or Perl that executes arbitrary system commands, then run it. This technique is effective because the CREATEFUNC privilege allows a database user to define user-defined functions, and when combined with a trusted procedural language such as plpythonu or plperl, those functions can execute operating system commands with the privileges of the database service account—typically the 'postgres' superuser. On the CompTIA PenTest+ PT0-002 exam, this scenario tests your understanding of database privilege escalation vectors beyond simple SQL injection, often appearing in the "Attacks and Exploits" domain. A common trap is assuming you need a superuser role to run system commands, but CREATEFUNC with a trusted language bypasses that restriction entirely. Memory tip: think "CREATE a FUNC to FUNCtion as the superuser."

PT0-002 Attacks and Exploits Practice Question

This PT0-002 practice question tests your understanding of attacks and exploits. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.

During an internal penetration test, a tester gains a shell as the 'www-data' user on a Linux server. The server runs a PHP web application that connects to a PostgreSQL database using credentials stored in a config file. The tester discovers that the PostgreSQL server trusts all local connections (no password required) and that the web application's database user has the 'CREATEFUNC' privilege. Which technique is most effective for escalating privileges to database administrator (superuser) and executing system commands as the database service account?

Question 1hardmultiple choice

Full question →

A
Use the stored credentials to log in as the web application user and run SELECT * FROM pg_shadow; to extract password hashes of other users.
Why wrong: While password hashes may be extracted, this does not immediately provide superuser privileges or command execution.
B
Create a PostgreSQL function using a trusted language like Python or Perl that executes arbitrary system commands, then run it.
This technique leverages CREATEFUNC to run shell commands as the database service account, enabling privilege escalation.
C
Exploit a kernel vulnerability to gain root access and then dump the database files.
Why wrong: Kernel exploits are possible but less direct and riskier; the PostgreSQL functional method is more reliable given the privileges.
D
Use the 'sudo' command to switch to the postgres user if the www-data user has sudo privileges.
Why wrong: The scenario does not indicate that www-data has sudo privileges, and this is not a reliable escalation path.

Full breakdown with real-world context →

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

✓

Create a PostgreSQL function using a trusted language like Python or Perl that executes arbitrary system commands, then run it.

Option B is correct because the 'CREATEFUNC' privilege allows the web application database user to create user-defined functions in PostgreSQL. By creating a function in a trusted language (e.g., Python, Perl, or C) that executes arbitrary system commands, the tester can run those commands with the privileges of the database service account (e.g., 'postgres'), effectively escalating to superuser-level control and executing system commands without needing a password.

Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

✗
Use the stored credentials to log in as the web application user and run SELECT * FROM pg_shadow; to extract password hashes of other users.
Why it's wrong here
While password hashes may be extracted, this does not immediately provide superuser privileges or command execution.
✓
Create a PostgreSQL function using a trusted language like Python or Perl that executes arbitrary system commands, then run it.
Why this is correct
This technique leverages CREATEFUNC to run shell commands as the database service account, enabling privilege escalation.
Related concept
Read the scenario before looking for a memorised answer.
✗
Exploit a kernel vulnerability to gain root access and then dump the database files.
Why it's wrong here
Kernel exploits are possible but less direct and riskier; the PostgreSQL functional method is more reliable given the privileges.
✗
Use the 'sudo' command to switch to the postgres user if the www-data user has sudo privileges.
Why it's wrong here
The scenario does not indicate that www-data has sudo privileges, and this is not a reliable escalation path.

Common exam traps

Common exam trap: answer the scenario, not the keyword

The trap here is that candidates may overlook the direct power of 'CREATEFUNC' in PostgreSQL and instead focus on password extraction (Option A) or generic kernel exploits (Option C), missing that database-level function creation is the most efficient and immediate escalation path.

Trap categories for this question

Command / output trap
While password hashes may be extracted, this does not immediately provide superuser privileges or command execution.
Scenario analysis trap
The scenario does not indicate that www-data has sudo privileges, and this is not a reliable escalation path.

Detailed technical explanation

How to think about this question

PostgreSQL's 'CREATEFUNC' privilege, combined with a trusted language like 'plpythonu' or 'plperl', allows execution of arbitrary code within the database server process. The function runs with the permissions of the PostgreSQL service account (e.g., 'postgres'), which often has full system access. In real-world scenarios, this technique is a common privilege escalation vector when database users have excessive privileges, as it bypasses the need for password cracking or kernel exploits.

KKey Concepts to Remember

Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.

TExam Day Tips

Watch for words such as best, first, most likely and least administrative effort.
Review why wrong options are wrong, not only why the correct option is correct.

Key takeaway

Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.

Real-world example

How this comes up in practice

A security team runs a vulnerability scan on a web application and discovers an unpatched SQL injection flaw. The team prioritises remediation by CVSS score — critical flaws are patched within 24 hours, high within 7 days. Questions like this test whether you understand vulnerability management processes, scanning tools, and remediation prioritisation.

What to study next

Got this wrong? Here's your next step.

Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.

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FAQ

Questions learners often ask

What does this PT0-002 question test?

Attacks and Exploits — This question tests Attacks and Exploits — Read the scenario before looking for a memorised answer..

What is the correct answer to this question?

The correct answer is: Create a PostgreSQL function using a trusted language like Python or Perl that executes arbitrary system commands, then run it. — Option B is correct because the 'CREATEFUNC' privilege allows the web application database user to create user-defined functions in PostgreSQL. By creating a function in a trusted language (e.g., Python, Perl, or C) that executes arbitrary system commands, the tester can run those commands with the privileges of the database service account (e.g., 'postgres'), effectively escalating to superuser-level control and executing system commands without needing a password.

What should I do if I get this PT0-002 question wrong?

Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.

What is the key concept behind this question?

Read the scenario before looking for a memorised answer.

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