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add posts for picoCTF!
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‎_posts/2025-07-08-picoctf-obedient-cat.md‎

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---
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title: Obedient Cat
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date: 2025-07-08
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categories: [Capture The Flags, picoCTF]
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tags: [ctf, picoctf, misc, writeups]
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description: picoCTF Obedient Cat Challenge
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---
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> Challenge description:
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>
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>This file has a flag in plain sight (aka "in-the-clear").
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{: .prompt-info }
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For this challenge, all you have to do is download the file and look inside it for the flag.
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```terminal
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~/training/picoCTF/obedient-cat
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❯ wget https://mercury.picoctf.net/static/fb851c1858cc762bd4eed569013d7f00/flag
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--2025-07-08 17:38:50-- https://mercury.picoctf.net/static/fb851c1858cc762bd4eed569013d7f00/flag
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Loaded CA certificate '/etc/ssl/certs/ca-certificates.crt'
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Resolving mercury.picoctf.net (mercury.picoctf.net)... 18.189.209.142
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Connecting to mercury.picoctf.net (mercury.picoctf.net)|18.189.209.142|:443... connected.
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HTTP request sent, awaiting response... 200 OK
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Length: 34 [application/octet-stream]
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Saving to: ‘flag’
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flag 100%[====================================>] 34 --.-KB/s in 0s
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2025-07-08 17:38:50 (98.9 MB/s) - ‘flag’ saved [34/34]
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~/training/picoCTF/obedient-cat
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❯ ls
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 flag
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~/training/picoCTF/obedient-cat
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❯ cat flag
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picoCTF{s4n1ty_v3r1f13d_28e8376d}
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```
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FLAG: `picoCTF{s4n1ty_v3r1f13d_28e8376d}`

‎_posts/2025-07-08-picoctf-wave-a-flag.md‎

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---
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title: Wave a flag
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date: 2025-07-08
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categories: [Capture The Flags, picoCTF]
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tags: [ctf, picoctf, misc, writeups]
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description: picoCTF Wave a flag Challenge
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---
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> Challenge description:
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>
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>Can you invoke help flags for a tool or binary? [This program](https://mercury.picoctf.net/static/a14be2648c73e3cda5fc8490a2f476af/warm) has extraordinarily helpful information...
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{: .prompt-info }
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For this challenge we were given a 64-bit binary, so we'll pop it into `Ghidra` to see whats in the `main()` function.
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```c
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void main(int argc,char **argv)
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{
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int iVar1;
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char **argv-local;
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int argc-local;
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if (argc == 1) {
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puts("Hello user! Pass me a -h to learn what I can do!");
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}
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else {
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iVar1 = strcmp(argv[1],"-h");
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if (iVar1 == 0) {
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puts(
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"Oh, help? I actually don\'t do much, but I do have this flag here: picoCTF{b1scu1ts_4nd_g r4vy_755f3544}"
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);
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}
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else {
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printf("I don\'t know what \'%s\' means! I do know what -h means though!\n",argv[1]);
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}
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}
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return;
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}
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```
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And the flag's right there!
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FLAG: `picoCTF{b1scu1ts_4nd_gr4vy_755f3544}`

‎_posts/2025-07-12-picoctf-bases.md‎

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---
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title: Bases
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date: 2025-07-12
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categories: [Capture The Flags, picoCTF]
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tags: [ctf, picoctf, misc, writeups]
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description: picoCTF Bases Challenge
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---
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> Challenge description:
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>
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>What does this `bDNhcm5fdGgzX3IwcDM1` mean? I think it has something to do with bases.
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{: .prompt-info }
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Alrighty, so we've been given a `base64` encoded string, and have to find out what it is. For this, we'll use both `echo` and `base64`.
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`base64` has a decode flag, which is `-d`. It decoded and text passed through to it In order to do that we'll need to use `echo` to pipe the text through. We need to be careful, since `echo` adds a newline to the end of the string, so we'll use the `-n` flag to disable that.
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Our final command looks like this:
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```terminal
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❯ echo "bDNhcm5fdGgzX3IwcDM1" | base64 -d
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l3arn_th3_r0p35
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```
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Add on the flag formatters, and we're all good to go!
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FLAG: `picoCTF{l3arn_th3_r0p35}`

‎_posts/2025-07-12-picoctf-first-grep.md‎

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---
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title: first grep
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date: 2025-07-12
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categories: [Capture The Flags, picoCTF]
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tags: [ctf, picoctf, misc, writeups]
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description: picoCTF first grep Challenge
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---
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> Challenge description:
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>
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>Can you find the flag in [file](https://jupiter.challenges.picoctf.org/static/495d43ee4a2b9f345a4307d053b4d88d/file)? This would be really tedious to look through manually, something tells me there is a better way.
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>
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{: .prompt-info }
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Okay, so here we've been given a pretty big file, and we need to pull out the flag. Now, we know that the flag starts with `picoCTF`, but how can we find it quickly in a large file? Well, we use `grep`!
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Now, you can use `grep` in one of two ways. We'll cover both here
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## Way #1
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The first way is to only use `grep` by itself. The syntax is `grep [string to search for] [file]`.
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```terminal
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❯ grep pico file
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picoCTF{grep_is_good_to_find_things_dba08a45}
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```
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## Way #2
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Now let's say you don't have a file, or you didn't like the first way for some reason. You can also use `cat` to send the file's contents to `stdout`, and pipe it into `grep`. Piping output to `grep` is useful is you're working with data not in a file, or trying to chain together a command.
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```terminal
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❯ cat file | grep pico
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picoCTF{grep_is_good_to_find_things_dba08a45}
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```
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Either way, you get the flag!
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FLAG: `picoCTF{grep_is_good_to_find_things_dba08a45}`

‎_posts/2025-07-12-picoctf-magikarp-ground-mission.md‎

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---
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title: Magikarp Ground Mission
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date: 2025-07-12
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categories: [Capture The Flags, picoCTF]
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tags: [ctf, picoctf, misc, writeups]
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description: picoCTF Magikarp Ground Mission Challenge
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---
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> Challenge description:
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>
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>Do you know how to move between directories and read files in the shell? Start the container, `ssh` to it, and then `ls` once connected to begin. Login via `ssh` as `ctf-player` with the password, `abcba9f7`
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{: .prompt-info }
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For this challenge, it's pretty darn simple. Once you're in, use `cat` to read the part of the flag, and then use `cat` again to read the instructions for the next part of the flag. After you've done that, `cd` to where the instructions pointed you, and continue from there.
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The process should look something like this:
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```terminal
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ctf-player@pico-chall$ ls
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1of3.flag.txt instructions-to-2of3.txt
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ctf-player@pico-chall$ cat 1of3.flag.txt
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picoCTF{xxsh_
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ctf-player@pico-chall$ cat instructions-to-2of3.txt
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Next, go to the root of all things, more succinctly `/`
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ctf-player@pico-chall$ cd /
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ctf-player@pico-chall$ ls
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2of3.flag.txt boot etc instructions-to-3of3.txt lib64 mnt proc run srv tmp var
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bin dev home lib media opt root sbin sys usr
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ctf-player@pico-chall$ cat 2of3.flag.txt
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0ut_0f_\/\/4t3r_
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ctf-player@pico-chall$ cat instructions-to-3of3.txt
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Lastly, ctf-player, go home... more succinctly `~`
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ctf-player@pico-chall$ cd ~
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ctf-player@pico-chall$ ls
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3of3.flag.txt drop-in
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ctf-player@pico-chall$ cat 3of3.flag.txt
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21cac893}
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```
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FLAG: `picoCTF{xxsh_0ut_0f_\/\/4t3r_21cac893}`

‎_posts/2025-07-12-picoctf-python-wrangling.md‎

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---
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title: Python Wrangling
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date: 2025-07-12
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categories:
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- Capture The Flags
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- picoCTF
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tags:
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- ctf
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- picoctf
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- misc
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- writeups
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description: picoCTF Python Wrangling Challenge
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---
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> Challenge description:
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>
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>Python scripts are invoked kind of like programs in the Terminal... Can you run [this Python script](https://mercury.picoctf.net/static/2ac2139344d2e734d5d638ac928f1a8d/ende.py) using [this password](https://mercury.picoctf.net/static/2ac2139344d2e734d5d638ac928f1a8d/pw.txt) to get [the flag](https://mercury.picoctf.net/static/2ac2139344d2e734d5d638ac928f1a8d/flag.txt.en)?
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>
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{: .prompt-info }
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For this challenge, we are given `ende.py`, `flag.txt.en`, and `pw.txt`
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Let's look at each file we're given.
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```python
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import sys
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import base64
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from cryptography.fernet import Fernet
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usage_msg = "Usage: "+ sys.argv[0] +" (-e/-d) [file]"
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help_msg = usage_msg + "\n" +\
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"Examples:\n" +\
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" To decrypt a file named 'pole.txt', do: " +\
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"'$ python "+ sys.argv[0] +" -d pole.txt'\n"
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if len(sys.argv) < 2 or len(sys.argv) > 4:
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print(usage_msg)
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sys.exit(1)
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if sys.argv[1] == "-e":
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if len(sys.argv) < 4:
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sim_sala_bim = input("Please enter the password:")
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else:
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sim_sala_bim = sys.argv[3]
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ssb_b64 = base64.b64encode(sim_sala_bim.encode())
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c = Fernet(ssb_b64)
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with open(sys.argv[2], "rb") as f:
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data = f.read()
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data_c = c.encrypt(data)
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sys.stdout.write(data_c.decode())
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elif sys.argv[1] == "-d":
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if len(sys.argv) < 4:
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sim_sala_bim = input("Please enter the password:")
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else:
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sim_sala_bim = sys.argv[3]
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ssb_b64 = base64.b64encode(sim_sala_bim.encode())
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c = Fernet(ssb_b64)
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with open(sys.argv[2], "r") as f:
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data = f.read()
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data_c = c.decrypt(data.encode())
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sys.stdout.buffer.write(data_c)
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elif sys.argv[1] == "-h" or sys.argv[1] == "--help":
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print(help_msg)
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sys.exit(1)
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else:
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print("Unrecognized first argument: "+ sys.argv[1])
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print("Please use '-e', '-d', or '-h'.")
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```
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{: file="ende.py" }
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```plaintext
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gAAAAABgUAIV8D5MJdzgLLTkkMlbU84ARVwfX4brMt2rJQCjkpLItytfWVZe1L2dp4K8VrKgRU3axStKJEAqcM0iDaxiYE54Boh8UfAAo1RNifKnlDrFz0gLaznVSFVj2xAUa4V35180
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```
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{: file="flag.txt.en" }
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```plaintext
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68f88f9368f88f9368f88f9368f88f93
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```
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{: file="pw.txt" }
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Hm, looks like a python script, an encoded flag, and the password to decrypt said flag. Let's run the python script and see what the usage looks like.
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```terminal
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❯ python ende.py
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Usage: ende.py (-e/-d) [file]
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```
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Okay, so since we want to decrypt, lets use the `-d` flag, along with the `flag.txt.en` file.
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```terminal
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❯ python ende.py -d flag.txt.en
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Please enter the password:
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```
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Alrighty, and let's throw the password in that we got from the `pw.txt` file.
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```terminal
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❯ python ende.py -d flag.txt.en
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Please enter the password:68f88f9368f88f9368f88f9368f88f93
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picoCTF{4p0110_1n_7h3_h0us3_68f88f93}
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```
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FLAG: `picoCTF{4p0110_1n_7h3_h0us3_68f88f93}`

‎_posts/2025-07-12-picoctf-whats-a-net-cat.md‎

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---
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title: what's a net cat?
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date: 2025-07-12
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categories: [Capture The Flags, picoCTF]
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tags: [ctf, picoctf, misc, writeups]
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description: picoCTF what's a net cat? Challenge
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---
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> Challenge description:
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>
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>Using netcat (nc) is going to be pretty important. Can you connect to `jupiter.challenges.picoctf.org` at port `25103` to get the flag?
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{: .prompt-info }
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`Netcat` is a nifty tool that lets you read/write data via network connections. It's definitely something important to learn on your cybersecurity journey.
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In order to use it in its most basic sense, your command will look something like this:
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```terminal
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nc [domain/IP address] [port]
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```
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So, if we need to connect to `jupiter.challenges.pictoctf.org` on port `25103`, It should look as such:
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```terminal
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❯ nc jupiter.challenges.picoctf.org 25103
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You're on your way to becoming the net cat master
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picoCTF{nEtCat_Mast3ry_d0c64587}
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```
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FLAG: `picoCTF{nEtCat_Mast3ry_d0c64587}`

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