PicoCTF 2019: All Answers- Part 1

1. 2Warm- 50 points

Can you convert the number 42 (base 10) to binary (base 2)?
Hint: Submit your answer in our competition’s flag format. For example, if your answer was ‘11111’, you would submit ‘picoCTF{11111}’ as the flag.

Answer: picoCTF{101010}

2. vault-door-training- 50 points

Your mission is to enter Dr. Evil’s laboratory and retrieve the blueprints for his Doomsday Project. The laboratory is protected by a series of locked vault doors. Each door is controlled by a computer and requires a password to open. Unfortunately, our undercover agents have not been able to obtain the secret passwords for the vault doors, but one of our junior agents obtained the source code for each vault’s computer! You will need to read the source code for each level to figure out what the password is for that vault door. As a warmup, we have created a replica vault in our training facility.
The source code for the training vault is here:

import java.util.*;

class VaultDoorTraining {
public static void main(String args[]) {
VaultDoorTraining vaultDoor = new VaultDoorTraining();
Scanner scanner = new Scanner(System.in);
System.out.print(“Enter vault password: “);
String userInput = scanner.next();
String input = userInput.substring(“picoCTF{“.length(),userInput.length()-1);
if (vaultDoor.checkPassword(input)) {
System.out.println(“Access granted.”);
} else {
System.out.println(“Access denied!”);
}
}

// The password is below. Is it safe to put the password in the source code?
// What if somebody stole our source code? Then they would know what our
// password is. Hmm… I will think of some ways to improve the security
// on the other doors.
//
// -Minion #9567
public boolean checkPassword(String password) {
return password.equals(“w4rm1ng_Up_w1tH_jAv4_be8d9806f18”);
}
}
Hint: The password is revealed in the program’s source code.
Answer: w4rm1ng_Up_w1tH_jAv4_be8d9806f18

3. Warmed Up- 50 points

What is 0x3D (base 16) in decimal (base 10)?
Hint: Submit your answer in our flag format. For example, if your answer was ‘22’, you would submit ‘picoCTF{22}’ as the flag.

Answer: picoCTF{61}

4. Insp3ct0r- 50 points

Kishor Balan tipped us off that the following code may need inspection: https://jupiter.challenges.picoctf.org/problem/44924/ (link) or http://jupiter.challenges.picoctf.org:44924
Hints: 1. How do you inspect web code on a browser?
2. There’s 3 parts

Answer: picoCTF{tru3_d3t3ct1ve_0r_ju5t_lucky?f10be399}

5. Glory of the Garden- 50 points

This garden contains more than it seems.

Hint: What is a hex editor?

Answer: picoCTF{more_than_m33ts_the_3y3eBdBd2cc}

6. The Numbers- 50 points

The numbers… what do they mean?

Hint: The flag is in the format PICOCTF{}

Answer: PICOCTF{THENUMBERSMASON}

7. Lets Warm Up- 50 points

If I told you a word started with 0x70 in hexadecimal, what would it start with in ASCII?
Hint: Submit your answer in our flag format. For example, if your answer was ‘hello’, you would submit ‘picoCTF{hello}’ as the flag.

Answer: picoCTF{p}

8. EASY 1- 100 points

The one time pad can be cryptographically secure, but not when you know the key. Can you solve this? We’ve given you the encrypted flag, key, and a table to help UFJKXQZQUNB with the key of SOLVECRYPTO. Can you use this table to solve it?.
Hint: 1. Submit your answer in our flag format. For example, if your answer was ‘hello’, you would submit ‘picoCTF{HELLO}’ as the flag.
2. Please use all caps for the message.

Answer: picoCTF{CRYPTOISFUN}

9. strings it- 100 points

Can you find the flag in file without running it?
Hint: strings

Answer: picoCTF{5tRIng5_1T_d66c7bb7}

10. where are the robots- 100 points

Can you find the robots? https://jupiter.challenges.picoctf.org/problem/60915/ (link) or http://jupiter.challenges.picoctf.org:60915
Hint: What part of the website could tell you where the creator doesn’t want you to look?

Answer: picoCTF{ca1cu1at1ng_Mach1n3s_8028f}

11. what’s a net cat?- 100 points

Using netcat (nc) is going to be pretty important. Can you connect to jupiter.challenges.picoctf.org at port 25103 to get the flag?

Hint: nc tutorial

Answer: picoCTF{nEtCat_Mast3ry_d0c64587}

12. logon- 100 points

The factory is hiding things from all of its users. Can you login as logon and find what they’ve been looking at? https://jupiter.challenges.picoctf.org/problem/13594/ (link) or http://jupiter.challenges.picoctf.org:13594
Hint: Hmm it doesn’t seem to check anyone’s password, except for logon’s?

Answers: Set the admin value to true and you will get the flag

picoCTF{the3_c0nsp1r4cy_l1v3s_d1c24fef}

13. Bases- 100 points

What does this bDNhcm5fdGgzX3IwcDM1 mean? I think it has something to do with bases.
Hint: Submit your answer in our flag format. For example, if your answer was ‘hello’, you would submit ‘picoCTF{hello}’ as the flag.

It is a base64 encoding. So we use a base64 decoder
Answer: picoCTF{l3arn_th3_r0p35}

14. Caesar- 100 points

This message is to be decrypted
picoCTF{ynkooejcpdanqxeykjrbdofgkq}

Hint: caesar cipher tutorial

Ceaser-cipher methods use the shift methods. In this case when you shift letter by 22 you will see the message
Answer: picoCTF{crossingtherubiconvfhsjkou}

15. vault-door-1- 100 points

This vault uses some complicated arrays! I hope you can make sense of it, special agent. The source code for this vault is here: VaultDoor1.java
import java.util.*;

class VaultDoor1 {
public static void main(String args[]) {
VaultDoor1 vaultDoor = new VaultDoor1();
Scanner scanner = new Scanner(System.in);
System.out.print(“Enter vault password: “);
String userInput = scanner.next();
String input = userInput.substring(“picoCTF{“.length(),userInput.length()-1);
if (vaultDoor.checkPassword(input)) {
System.out.println(“Access granted.”);
} else {
System.out.println(“Access denied!”);
}
}

// I came up with a more secure way to check the password without putting
// the password itself in the source code. I think this is going to be
// UNHACKABLE!! I hope Dr. Evil agrees…
//
// -Minion #8728
public boolean checkPassword(String password) {
return password.length() == 32 &&
password.charAt(0) == ‘d’ &&
password.charAt(29) == ‘9’ &&
password.charAt(4) == ‘r’ &&
password.charAt(2) == ‘5’ &&
password.charAt(23) == ‘r’ &&
password.charAt(3) == ‘c’ &&
password.charAt(17) == ‘4’ &&
password.charAt(1) == ‘3’ &&
password.charAt(7) == ‘b’ &&
password.charAt(10) == ‘_’ &&
password.charAt(5) == ‘4’ &&
password.charAt(9) == ‘3’ &&
password.charAt(11) == ‘t’ &&
password.charAt(15) == ‘c’ &&
password.charAt(8) == ‘l’ &&
password.charAt(12) == ‘H’ &&
password.charAt(20) == ‘c’ &&
password.charAt(14) == ‘_’ &&
password.charAt(6) == ‘m’ &&
password.charAt(24) == ‘5’ &&
password.charAt(18) == ‘r’ &&
password.charAt(13) == ‘3’ &&
password.charAt(19) == ‘4’ &&
password.charAt(21) == ‘T’ &&
password.charAt(16) == ‘H’ &&
password.charAt(27) == ‘5’ &&
password.charAt(30) == ‘2’ &&
password.charAt(25) == ‘_’ &&
password.charAt(22) == ‘3’ &&
password.charAt(28) == ‘0’ &&
password.charAt(26) == ‘7’ &&
password.charAt(31) == ‘e’;
}
}
Hint: Look up the charAt() method online.

Answer: picoCTF{d35cr4mbl3_tH3_cH4r4cT3r5_75092e}

16. What Lies Within- 150 points

There’s something in the building. Can you retrieve the flag?
Hint: There is data encoded somewhere… there might be an online decoder.

For this I have used online stegnography decoder

Answer: picoCTF{h1d1ng_1n_th3_b1t5}

17. shark on wire 1- 150 points

We found this packet capture. Recover the flag.
Hint: 1. Try using a tool like Wireshark
2. What are streams?

I found the flag under 6th stream
Answer: picoCTF{StaT31355_636f6e6e}

18. extensions- 150 points

This is a really weird text file TXT? Can you find the flag?
Hint: 1. How do operating systems know what kind of file it is? (It’s not just the ending!
2. Make sure to submit the flag as picoCTF{XXXXX}

You just have to change its extension from .txt to .png and thereby you will get the flag
Answer: picoCTF{now_you_know_about_extensions}

19. So Meta- 150 points

Find the flag in this picture.
Hints: 1. What does meta mean in the context of files?
2. Ever heard of metadata?

Answer: picoCTF{s0_m3ta_eb36bf44}

20. Tapping- 200 points

Theres tapping coming in from the wires. What’s it saying nc jupiter.challenges.picoctf.org 9422
Hint: 1. What kind of encoding uses dashes and dots?
2. The flag is in the format PICOCTF{}

. — . .. -.-. — — -.-. — ..-. { — — — — .-. … … — -.-. — — — -.. … — . — — … ..-. ..- -. .. — — -…. — -.. … — — -.. .. — — ….- -…. . — — — — — }

Morse encoding uses dashes and dots. So we paste the code in Morse decoder.

Answer: PICOCTF{M0RS3C0D31SFUN2683824610}

Hacker || Student || CTF Player || Coder || Editor at A&M Publications

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