New Info Sec Website Alert! – White Hat Academy

Hello All,

It’s been a LONG time since I have blogged. What can I say? Life happens.

Anyway, I have enrolled into a program called White Hat Academy.

This website is great for n00bs as there are lessons to learn about different topics such as bash scripting, stenography, forensics, and mobile.

After completing the lessons there is a Capture the Flag (CTF) challenge that will incorporate what you have learned.

Check it out (https://whitehat.academy/) and enroll today!

OverTheWire: Natas Level 7 – #appsec #webapp #websecurity #wargames

Another day, another challenge…

In today’s blog post we will solve level 7 from the Natas wargame challenge.

Let’s begin.

Going to the following link, and entering username “natas7” and password “7z3hEENjQtflzgnT29q7wAvMNfZdh0i9” we see the following:

Natas7_WarGame_1

Natas7_WarGame_2

Hmm… we see a Home and About links. Let’s click the links and see what happens.

Natas7_WarGame_3

Natas7_WarGame_4

After clicking the links we see there’s not much that’s showing on the screen.

Let’s view the source and see if there are any hints there.

Doing a right click, view page source we see:

Natas7_WarGame_5

Hmm… we see a comment that says, “password for webuser natas8 is in /etc/natas_webpass/natas8”

How can we use this information?

Looking at the above screenshots of Home and About – we notice that at the end of the URL it’s referencing a page. For instance for the home page it’s “page=Home” and for About it’s “page=About”. Let’s try to change the page name to the hint that was provided to us.

Changing the URL to: http://natas7.natas.labs.overthewire.org/index.php?page=/etc/natas_webpass/natas8, we see…

Natas7_WarGame_6

the flag!

PicoCTF 2017 – A Thing Called A Stack #ctf #picoctf #appsec #infosec #reverseengineering

Another day, another challenge.

In today’s blog post we’re going to solve the “A Thing Called A Stack” challenge from PicoCTF.

Let’s get started.

Clicking on the challenge, we see the following:

PicoCTF_A_Thing_Called_A_Stack_1

OK, so we’re given a file, and we need to determine the difference between the value of esp at the end of the code, and the location of the saved return address.

Looking at the hints we see the following:

PicoCTF_A_Thing_Called_A_Stack_2

We’ve encountered two different questions. Where is the return address saved, and what commands actually affect the stack.

DISCLAIMER: I haven’t worked with assembly in probably 8 years. So, what did I do? Go to YouTube.

Entering – “Assembly tutorial” I found a GREAT crash course on explaining assembly.

I have linked the video here.

Opening the file (Notepad++ is great!)

We see the following:

PicoCTF_A_Thing_Called_A_Stack_3

Using the YouTube tutorial, let’s decode the assembly code.

First we’re pushing the ebp (base pointer) onto the stack.

Next, we move the esp (stack pointer) to be at the same location to the base pointer.

Next, we push edi, esi, and ebx onto the stack. Note these instructions don’t change the stack. This solves question #2 in the hints section.

Next, we add 180 (0xb4 hex) to the stack to hold local variables.

Next, we’re going to store the local variable x = 0, to address 180 + 4 = 184

Next, we’re going to store the local variable y = 1,  to address 184 + 4 = 188

Next, we’re going to store the local variable z = 2, to address 188 + 4 = 192

Next, we’re going to store the local variable a = 3, to address 192 + 4 = 196

So now the esp (stack pointer) is now at 196.

Let’s convert 196 to hexadecimal.

Doing this we get the following: 0xc4

Entering this into the challenge, we see that solved the challenge and acquired 60 points!

PicoCTF 2017 – Special Agent User #appsec #infosec #forensics

Another day, another challenge.

Today’s blog post we will solving the “Special Agent User” challenge in the PicoCTF.

Let’s get started.

Clicking on the challenge we see:

PicoCTF_Special_Agent_1

We have another pcap (packet capture file) and we need to find the User Agent. OK. Sounds plausible. Let’s look at the hints.

PicoCTF_Special_Agent_2

There’s a link that discuss more about user-agents. Let’s go to that link.

Opening that link we see the following:

PicoCTF_Special_Agent_3

The web page explains the different components of the User-String. This will be useful.

Opening the packet capture file we notice the usual stuff UDP, and ICMP packets. And like with the first “Digital Camouflage” challenge we can ignore this.

User-Agent strings are found in HTTP requests. We need to look at packet captures for just HTTP requests.

Doing this we see a packet that’s piqued our interest…

PicoCTF_Special_Agent_4

On packet 80 (GET / HTTP/1.1) we’ll do a right click, Follow, HTTP stream.

Doing this we have the following:

PicoCTF_Special_Agent_5

Looking at the last entry in the user agent, we can see that the packet is using Firefox 25. Entering that as the flag, we’ve acquired 50 points!

PicoCTF 2017 – computeAES #infosec #appsec #crypto #ctf

Another day, another challenge.

Today’s blog post will explore solving the “computeAES” challenge in PicoCTF.

Let’s get started.

Clicking on the challenge we see the following:

PicoCTF_computeAES_1

Clicking on the clue link we see the following:

PicoCTF_computeAES_2

Going back to the challenge and clicking the hints we see:

PicoCTF_computeAES_3

Let’s use the hint of using online tools to solve this challenge.

Doing a Google search for “convert base64 to hex” we get the following link.

Going to this link we put in our base64 input to get the hex equivalent.

Doing this for the key and the input we get the following:

Key = 4f9b95cd8b6e04dbfabf08e886c955e3

Input = b75874a9b70e851405e44e3a6ec34b8a67db708e9e82b28fe0b1ed291de54f851d5a386cb0cf11412053ed2ffcadc472

Doing another Google search for “AES calc hex” we get the following link.

Entering the hex value of the key and input we get the following:

PicoCTF_computeAES_4

We found the flag! Copying the flag and removing the extra space we’ve acquired 50 points!

PicoCTF 2017 – Yarn #appsec #infosec #ctf

Another day, another challenge…

Today’s blog post we will solve the, “Yarn” challenge from PicoCTF.

Let’s get started.

Clicking on the challenge we see:

PicoCTF_Yarn_1

OK, we need to find a flag inside of a file, but we do not know what the file is.

Let’s look at the hints and see if that provides any clues.

PicoCTF_Yarn_2

Looking at the hints we’re provided with two questions. Possibly answering these questions will leads us to the flag.

Answer question #1 – “what does the string command use to determine if something is a string?” We decide to do a Google search to answer just that.

Doing this Google search we’re provided with the following link.

Reading the article we determine that the strings command prints the printable characters from a file.

Doing that we’re provided with the following screenshot:

PicoCTF_Yarn_3

We’ve answered question #1. Let’s answer question #2.

Question #2 – is there a way to change the length that the strings command look for?

Going back to the link we see that there is a way we can specify that there is a way to determine the length of strings we want to print.

How do we use this?

By adding the “-n <length you want to use>”

Doing this we get the following:

PicoCTF_Yarn_4

Scrolling down we see:

PicoCTF_Yarn_5

Hmm… I think we found the flag! “Submit_me_for_I_am_the_flag”

Putting this string as the flag we have acquired 55 points!