Key Highlights Ready to conquer the Pirate machine...

Key Highlights
Ready to conquer the Pirate machine on HackTheBox? This guide will walk you through everything you need to know. Here are the key takeaways from this challenge:

The Pirate machine features a buffer overflow vulnerability, which is the main focus of the exploit.
You’ll use tools like Ghidra for disassembly and a Python script for the final exploit.
Understanding the while loop and strncmp function in the source code is crucial for finding the vulnerability.
The goal is to bypass security checks and gain access to the admin panel.
This challenge is a great introduction to basic buffer overflow techniques for newcomers.
Introduction
Pirate HackTheBox
Pirate HackTheBox
Welcome to the exciting world of HackTheBox (HTB)! If you’re looking to dive into buffer overflow challenges, the Pirate machine is a fantastic starting point. While labeled as “Hard,” it’s designed to teach fundamental concepts in a hands-on way. To begin the Pirate HTB machine, you first need to connect to the HTB network and start the machine from your dashboard. From there, your first step will be to perform initial scans to understand what you’re up against. This guide will show you how to use tools like Ghidra and Python to analyze the binary, bypass the disabled canary, and exploit a while loop to gain control. Let’s get started on your pirate adventure!

Understanding the Pirate Machine on HackTheBox
The Pirate machine, also known as Space Pirate, is a unique challenge in the HackTheBox universe. Its primary goal is to teach a fundamental buffer overflow technique: redirecting the program’s flow. This involves understanding how a program’s memory can be manipulated when it reads more data than its buffer can handle.

Unlike many other machines, Pirate is very focused. It guides you toward a specific vulnerability within a while loop and a strncmp function. The challenge intentionally has a disabled canary, a security feature that would normally prevent such attacks. This setup creates a perfect learning environment for those new to binary exploitation. We’ll explore its unique features and compare it to other machines.

Initial Foothold
Reconnaissance and Environment Fingerprinting
Initial Port Discovery
The operation begins with a comprehensive port scan. In a professional engagement, speed and accuracy are balanced using tools like Rustscan or Nmap with aggressive service detection.

The scan reveals a classic Active Directory infrastructure:

Port 53 (DNS): Simple DNS Plus.
Port 88 (Kerberos): Essential for ticket-based authentication.
Port 389/636 (LDAP/S): The directory service, providing a wealth of information.
Port 445 (SMB): File sharing and remote administration.
Port 5985 (WinRM): Remote management endpoint.
AD Enumeration: Mapping the Territory
Using the provided credentials for the ‘pentest’ user, we validate the authentication against SMB and LDAP. A critical discovery here is the lack of LDAP signing on the Domain Controller. While SMB signing is required, the unprotected LDAP service presents a significant relay opportunity later in the engagement.

To ensure smooth Kerberos operations, we must handle the significant time skew (common in HTB environments) using tools like faketime. We also generate a specific krb5.conf file to point our tools directly to the pirate.htb KDC.

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From Low-Priv to Machine Account
The Pre-2k Compatibility Flaw
The first major vulnerability is the over-permissive “Pre-Windows 2000 Compatible Access” group. In legacy-hardened environments, this group often includes ‘Authenticated Users.’ This allows any domain user to read sensitive attributes of other objects that should otherwise be restricted.

By running the pre2k module in NetExec, we identify two pre-created computer accounts: M*** and E***. In a common administrative oversight, these accounts are often created with the password set identical to the sAMAccountName (minus the trailing dollar sign).

Obtaining the MS01$ TGT
Using the known password ‘m***’ for the ‘m***’ account, we successfully request a Kerberos Ticket Granting Ticket (TGT). This elevates our status from a low-priv user to a machine account, which often possesses more broad reading rights within the directory.

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Pivoting and Internal Network Discovery
gMSA Password Retrieval
Machine accounts like M*** often have the msDS-AllowedToRetrieveManagedPassword attribute set for specific Group Managed Service Accounts (gMSAs). By leveraging our control over MS01$, we can read the NTLM hash for g****.

Ligolo-ng: Building the Bridge
Upon gaining access to the DC via the gMSA account, we discover a dual-homed network configuration. The host is connected to an internal 192.168.X.X subnet. To explore this further, we deploy Ligolo-ng. Ligolo-ng is preferred over traditional SOCKS proxies due to its performance and ability to handle ICMP and UDP traffic natively through a TUN interface.

Scanning the internal network reveals W**** at 192.168.X.X. Crucially, SMB signing is disabled on W***, making it the perfect target for NTLM relay attacks.

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The W*** Compromise
Coercion and LDAP Relay
Since we control a gMSA account on the DC and W*** has SMB signing disabled, we can perform an NTLM relay. However, to relay to LDAP on the DC, we must use the --remove-mic flag in ntlmrelayx.py to bypass Message Integrity Code checks.

We use a coercion tool (like PetitPotam or PrinterBug) to force W*** to authenticate back to our attacker machine. The authentication is then relayed to the DC’s LDAP service, granting us an interactive LDAP shell in the context of the W*** machine account.

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Shadow Credentials and RBCD
Once inside the LDAP shell, we apply a Shadow Credential attack. By adding a KeyCredential to the msDS-KeyCredentialLink attribute of the W*** object, we can obtain a TGT for the machine account without ever knowing its password.

To escalate to local Administrator on W***, we implement Resource-Based Constrained Delegation (RBCD). We configure W*** to trust itself for delegation. This allows us to perform an S4U2Self/S4U2Proxy transition to impersonate the Domain Administrator specifically for services on W***.

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Domain Administrator – The Final Ascent
The a*** Pivot
During our secret dumping on W***, we recover the clear-text password for the user a***. Following the BloodHound path, we see that a*** has the ForceChangePassword right over a***.

After resetting the password for a***, we find that this administrative user has “WriteSPN” rights over the Domain Controller computer object (D***).

KCD with Protocol Transition & SPN Hijacking
This is the most technical phase of the machine. The goal is to abuse Kerberos Constrained Delegation with Protocol Transition.

The Discovery: a*** is allowed to delegate to the HTTP/W***.pirate.htb service.
The Hijack: Since we have WriteSPN rights on DC01$, we can move the HTTP/WEB01.pirate.htb SPN from the W*** object to the D*** object.
The Abuse: Now, the KDC believes the HTTP service for W*** resides on the DC. Because we have “Protocol Transition” enabled, we can request a service ticket for any user (Administrator) for this SPN.
The Swap: Using getST.py, we request the ticket but use the -altservice flag to rewrite the service to CIFS/DC01.pirate.htb.
Since the ticket is encrypted with the DC’s long-term key, the DC accepts the ticket as valid. We use this ticket to gain a SYSTEM shell on the Domain Controller via psexec.py.

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Overview of Pirate’s Difficulty and Unique Features
Although rated as a Hard machine, the Pirate challenge is considered an excellent entry point for learning about buffer overflow vulnerabilities. Its difficulty lies in understanding the concepts of binary exploitation, but the execution is straightforward once you grasp the basics. CTF participants typically approach the entrypoint for Space Pirate challenges by first running a security check on the binary to identify its protections.

A key feature of Pirate is that protections like the stack canary and Position Independent Executable (PIE) are disabled. The absence of a canary means the program won’t crash if you overwrite parts of the stack, which is exactly what a buffer overflow attack does. This intentional vulnerability makes it an ideal practice ground for pwn challenges.

Your goal is to redirect the program’s execution flow to a part of the code you wouldn’t normally be able to access. By sending a carefully crafted input, you can bypass the authentication checks and execute a command that reveals the flag. It’s a classic pwn exercise in a controlled setting.

How Pirate Compares to Other HackTheBox Machines
Pirate stands out from many other HackTheBox machines because of its focused, educational nature. While other machines might require a broad range of skills—from web exploitation to network analysis and privilege escalation through complex vectors—Pirate hones in on a single, classic vulnerability: a buffer overflow. The exploit is precise and doesn’t involve complex, multi-stage attacks.

Many HTB machines are designed to simulate real-world environments with multiple potential pathways, but Pirate is more like a guided lesson. The path to the admin panel is linear: find the overflow, calculate the right number of bytes for your payload, and craft the exploit. You won’t get lost in rabbit holes, which is common in more sprawling challenges.

For a clearer picture, here’s how Pirate compares to a more typical, multi-layered HTB machine, as often detailed in a writeup:

Feature Pirate (Space Pirate) Typical HTB Machine
Primary Vulnerability Simple Buffer Overflow Web vulnerabilities, misconfigurations, kernel exploits
Security Protections Canary and PIE disabled Multiple protections enabled (ASLR, NX, Canary)
Path to Root Linear and direct exploit Multi-stage, requires enumeration and lateral movement
Required Skillset Focused on binary exploitation (pwn) Broad (web, networking, forensics, reversing)
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Beginner’s Guide to Getting Started with Pirate HTB
Getting started with the Pirate HTB machine might seem daunting, but with the right approach and tools, it’s a manageable and rewarding challenge. Your first step is to set up your environment correctly. This involves having the necessary software ready for analysis and exploitation, such as Ghidra for reverse engineering and a Python environment for scripting.

No special accounts are needed beyond your standard HackTheBox access. The key is to be methodical. Start by downloading the binary and examining it closely before you even think about writing an exploit. The following sections will detail the specific tools you’ll need and offer some essential tips to guide you through your first attempt.

What You’ll Need: Tools, Accounts, and Resources for Pirate HackTheBox
To successfully tackle the Pirate challenge, you’ll need a few key tools and resources. You don’t need any special accounts, just your HackTheBox subscription to access the machine. The most important part is having the right software to analyze the binary and craft your exploit.

Here are the essential tools recommended for this challenge:

A Linux Environment: A distribution like Kali Linux or Parrot OS is ideal, as they come pre-loaded with many security tools.
Ghidra: This powerful, free reverse engineering tool from the NSA is perfect for disassembling the binary and understanding its code.
Python 3: You will use Python, along with the pwntools library, to write the script that sends the exploit payload.
Netcat (nc): A simple utility to connect to the remote port and interact with the running program.
Having these tools set up will make the process much smoother. If you get stuck, don’t hesitate to look at a high-level writeup for hints, but try to solve as much as you can on your own first. The learning is in the struggle!

Essential Tips for First-Time Users on Pirate HTB
If this is your first time attempting a buffer overflow challenge like Pirate, a methodical approach is your best friend. Don’t rush into writing code. The initial enumeration and analysis phase is where you’ll find the clues needed to succeed. Take your time to understand what the program does and how it works.

Here are some essential tips to keep in mind as you begin:

Analyze the Binary First: Before anything else, use checksec to see what security protections are enabled or disabled. This will immediately tell you that a buffer overflow is a likely attack vector.
Be Precise with Your Payload: Buffer overflows are all about precision. You need to calculate the exact number of bytes required to overwrite the buffer and hijack the instruction pointer. A single byte off can cause the exploit to fail.
Read the Code Carefully: In Ghidra, pay close attention to the read function calls. Note the size of the buffer and how many bytes the program reads into it. The discrepancy is your vulnerability.
Remember that this challenge might take a few tries. Remote instances can be unstable, so if your exploit doesn’t work the first time, don’t be discouraged. Wrap your exploit script in a loop to handle potential connection issues and ensure you capture the flag.

Step-by-Step Guide: Pirate HTB Machine
Ready for a walkthrough of the Pirate challenge? This step-by-step guide will break down the process from initial analysis to final flag capture. We’ll start with enumeration to understand the binary, then move on to finding the vulnerability and crafting the buffer overflow exploit. This process is a foundational skill in binary exploitation.

We will use Ghidra to decompile the code and identify the weak points. From there, we’ll calculate the payload and write a simple script to execute the attack. Follow these steps, and you’ll see how a seemingly complex challenge can be broken down into manageable parts.

Step 1: Initial Enumeration and Scanning Techniques
Your journey begins with enumeration. After starting the Pirate machine on HackTheBox and connecting to its IP address, the first thing you should do is download the provided binary file. Once you have it on your local machine, the initial step is to run the checksec command on it. This utility gives you a quick overview of the security protections compiled into the binary.

For the Pirate binary, checksec will reveal that key protections like Canary and Position Independent Executable (PIE) are disabled. This is your biggest clue. A disabled canary means the program won’t detect stack corruption, and disabled PIE means the program’s memory addresses are static, making it much easier to redirect code execution.

Next, run the program to see how it behaves. You’ll encounter a simple menu. Interacting with it doesn’t reveal much, which tells you that the vulnerability isn’t in the user interface logic but deeper within the code itself. This initial enumeration confirms that a buffer overflow is not only possible but the intended path.

Step 2: Discovering Entry Points and Exploiting Vulnerabilities
With the initial analysis done, it’s time to find the entry point for your exploit. This is where a disassembler like Ghidra becomes invaluable. Open the binary in Ghidra and let it analyze the code. Most C programs start their main logic in the main() function, but for this challenge, the interesting code is inside the admin_panel() function.

Navigating to admin_panel(), you will see the program’s logic laid out. Look for where the program accepts user input. You will find a read function call: read(0, local_38, 0x39). This is the smoking gun. The code is reading 0x39 (57) bytes of input into a buffer named local_38, which Ghidra shows has a size of only 40 bytes. This mismatch is the buffer overflow vulnerability.

The goal is to overflow this buffer and overwrite the return address on the stack. By controlling the return address, you can redirect the program’s execution to another part of the code. In this case, you want to jump to the part of the function that contains the system("cat flag*") command, bypassing all the authentication checks that come before it.

Step 3: Buffer Overflow Exploitation in Pirate HackTheBox
Now you can exploit the buffer overflow you discovered. Since there is no canary to worry about, the process is a classic pwn exercise. Your task is to craft a payload that fills the buffer, overwrites any variables between the buffer and the return address, and finally replaces the return address with the address of your target instruction.

First, you need to determine the exact offset to the return address. This usually involves some trial and error with a pattern of unique characters (a “De Bruijn pattern”) and a debugger, but for this challenge, the offset is 56 bytes. You will send 56 “junk” bytes (like ‘A’s) to fill the buffer and overwrite the stack up to the return address.

After the 56 bytes of padding, you need to provide the new return address. Using Ghidra, find the memory address of the instruction right before system("cat flag*") is called. In this case, it’s e.sym.admin_panel + 297. You’ll append this address to your payload, making sure to pack it in the correct format (64-bit little-endian, using p64() from pwntools). When the function attempts to return, it will jump to your chosen address, execute the command, and give you the flag.

Step 4: Privilege Escalation and Capturing the Flags
In the context of the Pirate challenge, “privilege escalation” isn’t about gaining root on the system but about elevating your access within the program itself. The goal is to bypass the normal user flow and access the functionality reserved for the admin panel. Your buffer overflow exploit achieves exactly this by hijacking the program’s control flow.

Once your payload is crafted, you’ll use a Python script with the pwntools library to send it to the server. The script connects to the target IP and port, sends the menu option to trigger the vulnerable input field, and then sends your payload: 56 bytes of padding followed by the target address. This is the standard approach CTF participants use for this entry point.

Because the remote instance can sometimes be unstable, it’s a good practice to wrap your exploit logic in a try-except block inside a while loop. This ensures that if the connection drops or the exploit fails for a transient reason, your script will simply try again until it successfully receives the flag. A successful exploit will print the contents of the flag file, completing the challenge. Congratulations, you’ve captured the flag!

Common Challenges and How to Overcome Them in Pirate HackTheBox
Even with a clear path, the Pirate challenge can present a few hurdles, especially for newcomers to buffer overflow exploits. A common issue is getting the payload exact. A single byte off can mean the difference between success and failure. Another challenge is dealing with the potential instability of the remote server, which can make a perfectly good exploit fail intermittently.

To avoid these pitfalls, precision and persistence are key. Double-check your offset calculations and memory addresses. When things don’t work, don’t assume your logic is wrong right away—it could just be a connection issue. We’ll cover how to troubleshoot your exploit and stay on track.

Troubleshooting Buffer Overflow and Exploitation Issues
When your buffer overflow exploit doesn’t work, it’s time for some troubleshooting. The most common culprit in a pwn challenge like this is an incorrect offset or memory address. Since the stack canary is disabled, the program won’t crash in a helpful way, so you need to be systematic in your debugging.

If you’re struggling to get the exploit right, here are a few things to check:

Verify Your Offset: Are you sure about the 56-byte offset? Test it locally if possible. Send a pattern of characters and see where the program crashes or which value overwrites the instruction pointer.
Check the Target Address: Double-check the address you are jumping to. Make sure it’s the correct address for the instruction that leads to the flag-printing function. An incorrect address will send the program into an invalid memory region.
Endianness Matters: Ensure you are packing the address correctly. For a 64-bit binary, you need to use p64() from pwntools to convert the address into little-endian format.
Sometimes, the issue isn’t your code but the remote environment. If you’re confident in your exploit, try running it multiple times. The server might be flaky, and persistence can pay off.

Avoiding Pitfalls and Staying on Track in the Pirate HTB Writeup
Staying on track during the Pirate HTB challenge means avoiding common pitfalls that can send you down the wrong path. One of the biggest distractions is the “unintended solution” mentioned in some writeups. While there’s a way to pass the strncmp function check directly, it’s not the primary learning objective. Focusing on the buffer overflow is the intended path.

Here are a few tips to avoid getting stuck and to stay focused:

Don’t Overthink the Logic: The vulnerability is a simple buffer overflow. Don’t get bogged down in the complex if statements or the while loop logic that handles menu choices. The weakness is purely in the read function call.
Trust Your Tools: checksec told you the binary was vulnerable. Ghidra showed you where. Trust this initial analysis and focus your efforts there.
Count Your Bytes Carefully: The difference between 0x39 and 40 bytes is the key. Make sure you understand how many bytes you need for padding and how many for the address. Every byte counts.
By keeping your approach simple and methodical, you can avoid these common traps. Concentrate on overflowing the buffer and redirecting execution—that’s the core of this challenge.

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