Review - GIAC Exploit Researcher and Advanced Penetration Tester (GXPN) Review

A few weeks ago I passed the GIAC Exploit Researcher and Advanced Penetration Tester (GXPN) certification exam. This is the exam offered after their SEC660: Advanced Penetration Testing, Exploit Writing, and Ethical Hacking course. Below is my review.

RickdiculouslyEasy: 1 - Walkthrough

It has been a long time since I've last posted anything off of Vulnhub. To be honest, I just haven't had too much time to dive into any of these VM's. However, g0tmi1k released a ton of new VM's so I wanted to check them out. One of which is was RickdiculouslyEasy: 1 made by Luke.

This VM is based off the tv show Rick and Morty. I, myself, am a fan of this show so I had to check it out. It turned out to be quite easy but I still had fun solving it. Below is my walkthrough on capturing all of the flags. 

Elevate from Admin to NT Authority\SYSTEM

Elevate from Admin to NT Authority\SYSTEM

The other day I gained Administrative access to a windows machine. While I was enumerating around, I had the urge to escalate to the most powerful account on a Windows local instance: NT Authority\SYSTEM.

I realized there weren't a lot of posts online about it. I figured I'd give the steps I did in order to accomplish this task.

64Base - Walkthrough

It's been a while since I've been able to work on a vulnhub image. I started looking at recent releases and came across 64base. This VM has a Star Wars theme which is always great. Plus, it was 3mrgnc3's first public VM so I had to check it out!

Protostar - stack4

This is my fifth post on the Protostar series hosted by Exploit Exercises

We start off with understanding what is being asked of us:

About

Stack4 takes a look at overwriting saved EIP and standard buffer overflows.
This level is at /opt/protostar/bin/stack4
Hints

• A variety of introductory papers into buffer overflows may help.
• gdb lets you do “run < input”
• EIP is not directly after the end of buffer, compiler padding can also increase the size.

Source code

#include <stdlib.h>
#include <unistd.h>
#include <stdio.h>
#include <string.h>

void win()
{
  printf("code flow successfully changed\n");
}

int main(int argc, char **argv)
{
  char buffer[64];

  gets(buffer);
}

Nebula - level08

This is my ninth post on the Nebula series hosted by Exploit Exercises

We start off with understanding what is being asked of us:

About

World readable files strike again. Check what that user was up to, and use it to log into flag08 account.
To do this level, log in as the level08 account with the password level08. Files for this level can be found in /home/flag08.

Source code

There is no source code available for this level

Protostar - stack3

This is my fourth post on the Protostar series hosted by Exploit Exercises

We start off with understanding what is being asked of us:

About

Stack3 looks at environment variables, and how they can be set, and overwriting function pointers stored on the stack (as a prelude to overwriting the saved EIP)
Hints

• both gdb and objdump is your friend you determining where the win() function lies in memory.

This level is at /opt/protostar/bin/stack3

Source code

#include <stdlib.h>
#include <unistd.h>
#include <stdio.h>
#include <string.h>

void win()
{
  printf("code flow successfully changed\n");
}

int main(int argc, char **argv)
{
  volatile int (*fp)();
  char buffer[64];

  fp = 0;

  gets(buffer);

  if(fp) {
      printf("calling function pointer, jumping to 0x%08x\n", fp);
      fp();
  }
}

Nebula - level07

This is my eighth post on the Nebula series hosted by Exploit Exercises

We start off with understanding what is being asked of us:

Level07

The flag07 user was writing their very first perl program that allowed them to ping hosts to see if they were reachable from the web server.
To do this level, log in as the level07 account with the password level07. Files for this level can be found in /home/flag07.

Source code

#!/usr/bin/perl

use CGI qw{param};

print "Content-type: text/html\n\n";

sub ping {
  $host = $_[0];

  print("<html><head><title>Ping results</title></head><body><pre>");

  @output = `ping -c 3 $host 2>&1`;
  foreach $line (@output) { print "$line"; }

  print("</pre></body></html>");
  
}

# check if Host set. if not, display normal page, etc

ping(param("Host"));

Protostar - stack2

This is my third post on the Protostar series hosted by Exploit Exercises

We start off with understanding what is being asked of us:

About

Stack2 looks at environment variables, and how they can be set.
This level is at /opt/protostar/bin/stack2

Source code

#include <stdlib.h>
#include <unistd.h>
#include <stdio.h>
#include <string.h>

int main(int argc, char **argv)
{
  volatile int modified;
  char buffer[64];
  char *variable;

  variable = getenv("GREENIE");

  if(variable == NULL) {
      errx(1, "please set the GREENIE environment variable\n");
  }

  modified = 0;

  strcpy(buffer, variable);

  if(modified == 0x0d0a0d0a) {
      printf("you have correctly modified the variable\n");
  } else {
      printf("Try again, you got 0x%08x\n", modified);
  }

}

Nebula - level06

This is my seventh post on the Nebula series hosted by Exploit Exercises

We start off with understanding what is being asked of us:

About

The flag06 account credentials came from a legacy unix system.
To do this level, log in as the level06 account with the password level06. Files for this level can be found in /home/flag06.

Source code

There is no source code available for this level