CTFlearn

Base 2 2 the 6

Category: Cryptography

Description

There are so many different ways of encoding and decoding information nowadays… One of them will work! Q1RGe0ZsYWdneVdhZ2d5UmFnZ3l9

Solution

The title is the answer. 2⁶ = 64, so we’ll try to decode it with Base64 using CyberChef or any other decoder. We get our flag

CTF{FlaggyWaggyRaggy}

Basic Injection

Category: Web

Description

See if you can leak the whole database using what you know about SQL Injections. link.

Solution

To solve this, simply input OR 1=1; # or ' OR 1=1;-- (with a space after double dash). This leaks the database and gives us the answer

Name: fl4g__giv3r
Data: CTFlearn{th4t_is_why_you_n33d_to_sanitiz3_inputs} 

Binwalk

Category: Forensics

Description

Here is a file with another file hidden inside it. Can you extract it? https://mega.nz/#!qbpUTYiK!-deNdQJxsQS8bTSMxeUOtpEclCI-zpK7tbJiKV0tXYY

Solution

Downloaded file is an image. Running binwalk --dd='.*' command on the image extracts all files hidden in the .jpeg. One of them is a PNG, containing the flag

ABCTF{b1nw4lk_is_us3ful}

Character Encoding

Category: Cryptography

Description

In the computing industry, standards are established to facilitate information interchanges among American coders. Unfortunately, I’ve made communication a little bit more difficult. Can you figure this one out? 41 42 43 54 46 7B 34 35 43 31 31 5F 31 35 5F 55 35 33 46 55 4C 7D

Solution

Decode the values using CyberChef or any other hex decoder and you get the flag

ABCTF{45C11_15_U53FUL}

Forensics 101

Category: Forensics

Description

Think the flag is somewhere in there. Would you help me find it? https://mega.nz/#!OHohCbTa!wbg60PARf4u6E6juuvK9-aDRe_bgEL937VO01EImM7c

Solution

The downloaded file is a .jpg Minions meme. Running strings command on the file (or opening it with any text editor) reveals our flag

flag{wow!_data_is_cool}

So many 64s

Category: Cryptography

Description

Help! My friend stole my flashdrive that had the flag on it. When he gave it back the flag was changed! Can you help me decrypt it? https://mega.nz/#!OHhUyIqA!H9WxSdG1O7eVcCm0dffggNB0-dBemSpBAXiZ0OXJnLk

Solution

We download a .txt file containing a long string. Each Base64 decode makes the string shorter, so we can try to decode it manually, feeding the output into input using tools like CyberChef or write a simple script to automate the work.

import base64
message = open("flag.txt").read()

# decode if possible, if not - we decoded what we could, just print the message
while True:
    try:
        message = base64.b64decode(message)
    except Exception:
        break

print(bytes.decode(message))

We get our flag

ABCTF{pr3tty_b4s1c_r1ght?}

Taking LS

Category: Forensics

Description

Just take the Ls. Check out this zip file and I be the flag will remain hidden. https://mega.nz/#!mCgBjZgB!_FtmAm8s_mpsHr7KWv8GYUzhbThNn0I8cHMBi4fJQp8

Solution

Downloaded file is a .zip archive. Unzip and we can find a folder called The Flag. Enter it, run ls -la command to find .ThePassword directory. Enter again and view ThePassword.txt with help of cat or similar command

Nice Job!  The Password is "Im The Flag".

Wrapping the password into our flag format we get

CTFlearn{Im The Flag}

Where Can My Robot Go?

Category: Miscellaneous

Description

Where do robots find what pages are on a website? Hint: What does disallow tell a robot?

Solution

According to Google, robots.txt is a file that blocks search engines from indexing pages and assets on your site. With that knowledge, let’s visit https://ctflearn.com/robots.txt. We can see that page 70r3hnanldfspufdsoifnlds.html is hidden from indexing. Visiting the page gives us our flag

CTFlearn{r0b0ts_4r3_th3_futur3}

Wikipedia

Category: Miscellaneous

Description

Not much to go off here, but it’s all you need: Wikipedia and 128.125.52.138

Solution

As the description says, visit the English version of Wikipedia and search for 128.125.52.138. We see one entry. Inspecting the diff link we notice

In a certain CTF competition, the flag to a certain problem is "cNi76bV2IVERlh97hP".

Wrap it in standard flag format and submit to get the points.

CTFlearn{cNi76bV2IVERlh97hP}