Lookey here Description Attackers have hidden information in a very large mass of data in the past, maybe they are still doing it. Download the data here. Solving Download File Cat File | grep picoCTF* You also can grep directly with grep -o "picoCTF{.*}" Feel free to use the getflag script. #!/bin/bash echo "Getting flag for you…" grep -o "picoCTF{.*}"
File types Description This file was found among some files marked confidential but my pdf reader cannot read it, maybe yours can. You can download the file from here. Solving The file Flag.pdf isn’t a pdf file If you check it with file Flag.pdf, you’ll see, that it is a shell archive Flag.pdf: shell archive text If you execute this
Enhance! Description Download this image file and find the flag. Download image file Solving Lets have a look at the svg file It looks like a normal file In the last lines of the file, in the tspan tag, we can see some interessting characters… looks like the end of the flag. id=“tspan3764″>F { 3 n h 4 n c
buffer overflow 1 Description Control the return address Now we’re cooking! You can overflow the buffer and return to the flag function in the program. You can view source here. And connect with it using nc saturn.picoctf.net 51721 Info The links could be different.. the instance will be different (you have to launch your own in CTF) Solving This is
buffer overflow 0 Description Smash the stack Let’s start off simple, can you overflow the correct buffer? The program is available here. You can view source here. And connect with it using: nc saturn.picoctf.net 65445 Solving Download the sourcecode and the program If we check the sourcecode we will see, that a sigsev will give us a flag Playing with
RPS Description Here’s a program that plays rock, paper, scissors against you. I hear something good happens if you win 5 times in a row. Connect to the program with netcat: nc saturn.picoctf.net 53296 The program’s source code with the flag redacted can be downloaded here. Solving Checking the code (as mentioned in the hint of the challenge) In the
flag leak Description Story telling class 1/2 I’m just copying and pasting with this program. What can go wrong? You can view source here. And connect with it using: nc saturn.picoctf.net 51385 Solving This is a format string attack. So if we use some magic to send some format strings to the app, this should get us the flag. Here
Substitution Challenges Because this challenges are all very similar, we will not describe them in own articles 🙂 . Solving Substitutions cypher replace the 26 letters of an alphabet with other letters (one letter matches only one other). If you can find out which letter was replaced with which letter, then you can crack this cypher relatively easily. The best
rail-fence Description A type of transposition cipher is the rail fence cipher, which is described here. Here is one such cipher encrypted using the rail fence with 4 rails. Can you decrypt it? Download the message here. Put the decoded message in the picoCTF flag format, picoCTF{decoded_message}. Solving So – there is everything we need to know in the challenge
diffie-hellman Description Alice and Bob wanted to exchange information secretly. The two of them agreed to use the Diffie-Hellman key exchange algorithm, using p = 13 and g = 5. They both chose numbers secretly where Alice chose 7 and Bob chose 3. Then, Alice sent Bob some encoded text (with both letters and digits) using the generated key as