> For the complete documentation index, see [llms.txt](https://codingmace.gitbook.io/masterward/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://codingmace.gitbook.io/masterward/ctf/2019/picoctf/general.md). # General Skills ### Lets Warm Up \[50 pts] > **Description** > > If I told you a word started with 0x70 in hexadecimal, what would it start with in ASCII? **Solution** Searched 0x70 to ASCII in search engine **Flag: picoCTF{p}** ### Warmed Up \[50 pts] > **Description** > > What is 0x3D (base 16) in decimal (base 10)? **Solution** Doing this by math we have 3 \* 16^1 + D (13) \* 16^0 = 61 **Flag: picoCTF{61}** ### 2Warm \[50 pts] > **Description** > > Can you convert the number 42 (base 10) to binary (base 2)? **Solution** 2 ^ 6 = 64 and 2 ^ 5 = 32 which 42 is in that so their are 6 bits for 42. XXXXXX\ 42 / 2 = 21 remainder 0\ 21 / 2 = 10 remainder 1\ 10 / 2 = 5 remainder 0\ 5 / 2 = 2 remainder 1\ 2 / 2 = 1 remainder 0\ 1 / 2 = 0 remainder 1\ So 42 = the remainders above **Flag: picoCTF{101010}** ### what's a net cat? \[100 pts] > **Description** > > Using netcat (nc) is going to be pretty important. Can you connect to `jupiter.challenges.picoctf.org` at port `64287` to get the flag? **Solution** I could do the conventional `nc jupiter.challenges.picoctf.org 64287` into the terminal and get the response, but I wanted to do it in some code since not all problems can be solved through terminal. ```python import sys import socket hostname = "jupiter.challenges.picoctf.org" port = 64287 def netcat(hn , p): sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM) sock.connect((hn, p)) while True: data = sock.recv(1024) if (not data): break print(data) netcat(hostname, port) ``` **Flag: picoCTF{nEtCat\_Mast3ry\_284be8f7}** ### strings it \[100 pts] > **Description** > > Can you find the flag in [file](https://jupiter.challenges.picoctf.org/static/5bd86036f013ac3b9c958499adf3e2e2/strings) without running it? **Solution** It gives the hint to not run the file so you can get the flag with 1 command ```bash $ strings strings | grep "picoCTF" ``` **Flag: picoCTF{5tRIng5\_1T\_827aee91}** ### Bases \[100 pts] > **Description** > > What does this `bDNhcm5fdGgzX3IwcDM1` mean? I think it has something to do with bases. **Solution** Just going to go out on a limb and say it is the most common one of base64 ```python import base64 print(base64.b64decode("bDNhcm5fdGgzX3IwcDM1")) ``` **Flag: picoCTF{l3arn\_th3\_r0p35}** ### First Grep \[100 pts] > **Description** > > 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. **Solution** ```python cat file | grep "picoCTF" ``` **Flag: picoCTF{grep\_is\_good\_to\_find\_things\_dba08a45}** ### Based \[200 pts] > **Description** > > To get truly 1337, you must understand different data encodings, such as hexadecimal or binary. Can you get the flag from this program to prove you are on the way to becoming 1337? Connect with `nc jupiter.challenges.picoctf.org 29221`. **Solution** I connected and the second line was the answer to the first question (Binary). I was then given more numbers which made me choose to write some code for this solution. It was trial and error for most of it but in the end got the solution that it would be decoding in base 2, 8, 16 in that order. ```python import sys import socket import time hostname = "jupiter.challenges.picoctf.org" port = 29221 def known_base(a, base): res ="" for unit in a.split(" "): try: c = chr(int(unit, base)) if not c.isalpha(): raise Exception("Non-ascii") res += c except: pass return res def readData(sock, keyWord): data = "" while True: data += sock.recv(2) if keyWord in data: break return data def cleanData(data): start = data.index("the ") + 4 end = data.index("as a word") return data[start:end].strip() def netcat(hn , p): sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM) sock.connect((hn, p)) data = readData(sock, "Input:") sock.recv(1) enc_data = cleanData(data) myAnswer = known_base(enc_data, 2) print("Data given", enc_data) print("My Answer" , myAnswer) sock.sendall(myAnswer + "\n") time.sleep(.1) data = readData(sock, "Input:") enc_data = cleanData(data) myAnswer = known_base(enc_data, 8) sock.sendall(myAnswer + "\n") print("Data given", enc_data) print("My answer", myAnswer) time.sleep(.1) data = readData(sock, "Input:") enc_data = cleanData(data) print("Data given", enc_data) myAnswer = enc_data.decode('hex') print("My answer", myAnswer) sock.sendall(myAnswer + "\n") print(readData(sock, "}")) netcat(hostname, port) ``` **Flag: picoCTF{learning\_about\_converting\_values\_00a975ff}** ### plumbing \[200 pts] > **Description** > > Sometimes you need to handle process data outside of a file. Can you find a way to keep the output from this program and search for the flag? Connect to `jupiter.challenges.picoctf.org 7480`. **Solution** It says to keep the output so my mind goes to using '>' onto a file and then using grep to search the file ```python $ nc jupiter.challenges.picoctf.org 7480 > output.txt $ cat output.txt | grep "picoCTF" ``` or can combine that all into 1 line ```python nc jupiter.challenges.picoctf.org 7480 | grep "picoCTF" ``` **Flag: picoCTF{digital\_plumb3r\_06e9d954}** ### mus1c \[300 pts] > **Description** > > I wrote you a [song](https://jupiter.challenges.picoctf.org/static/c594d8d915de0129d92b4c41e25a2313/lyrics.txt). Put it in the picoCTF{} flag format. **Solution** I will admit this one would not have been possible without the hint. I looked at the title and was thinking it was an audacity problem but boy was I wrong. \ Hint: Do you think you can master rockstar?\ I searched that on google and of course a lot of writeups came up, but a result after that was a [website ](https://codewithrockstar.com/)to look into. Taking out input > Pico's a CTFFFFFFF my mind is waitin It's waitin\ > Put my mind of Pico into This my flag is not found put This into my flag put my flag into Pico\ > shout Pico shout Pico shout Pico\ > My song's something put Pico into This\ > Knock This down, down, down put This into CTF\ > shout CTF my lyric is nothing Put This without my song into my lyric Knock my lyric down, down, down\ > shout my lyric\ > Put my lyric into This Put my song with This into my lyric Knock my lyric down\ > shout my lyric\ > Build my lyric up, up ,up\ > shout my lyric shout Pico shout It\ > Pico CTF is fun security is important Fun is fun Put security with fun into Pico CTF Build Fun up shout fun times Pico CTF put fun times Pico CTF into my song\ > build it up\ > shout it shout it\ > build it up, up shout it shout Pico When put in both boxes Rock outputs > 114\ > 114\ > 114\ > 111\ > 99\ > 107\ > 110\ > 114\ > 110\ > 48\ > 49\ > 49\ > 51\ > 114 Which can be solved by the [website ](https://gchq.github.io/CyberChef/#recipe=From_Decimal\('Line%20feed',false\))to get the flag. **Flag: picoCTF{rrrocknrn0113r}** ### flag\_shop \[300 pts] \[Not Solved] > **Description** > > There's a flag shop selling stuff, can you buy a flag? [Source](https://jupiter.challenges.picoctf.org/static/64e724ad327f83ad833d9c6baa072b1f/store.c). Connect with `nc jupiter.challenges.picoctf.org 4906`. **Solution** a **Flag:** ### 1\_wanna\_b3\_a\_r0ck5tar \[350 pts] > **Description** > > I wrote you another [song](https://jupiter.challenges.picoctf.org/static/b99c57e4274172bf3c93534b6d59632d/lyrics.txt). Put the flag in the picoCTF{} flag format **Solution - Not Accepting Flag** This time I know it will be dealing with rockstar so I was like let's get it and actually downloaded the code trying to understand it more. I did all the installs and ran the file lyrics ```python Rocknroll is right Silence is wrong A guitar is a six-string Tommy's been down Music is a billboard-burning razzmatazz! Listen to the music If the music is a guitar Say "Keep on rocking!" Listen to the rhythm If the rhythm without Music is nothing Tommy is rockin guitar Shout Tommy Music is amazing sensation Jamming is awesome presence Scream Music Scream Jamming! Tommy is playing rock Scream Tommy! They are dazzled audiences Shout it! Rock is electric heaven Scream it! Tommy is jukebox god Say it! Break it down Shout "Bring on the rock!" Else Whisper "That ain't it, Chief" Break it down ``` Turned into code of this ```python Rocknroll = True Silence = False a_guitar = 10 Tommy = 44 Music = 170 the_music = input() if the_music == a_guitar: print("Keep on rocking!") the_rhythm = input() if the_rhythm - Music == False: Tommy = 66 print(Tommy!) Music = 79 Jamming = 78 print(Music!) print(Jamming!) Tommy = 74 print(Tommy!) They are dazzled audiences print(it!) Rock = 86 print(it!) Tommy = 73 print(it!) break print("Bring on the rock!") Else print("That ain't it, Chief") break ``` I noticed it didn't look right at all. At this point, I could have just said let me take the numbers and convert myself `66 79 78 74 86 73` == BONJVI, but why was it not working.\ 1\. I removed the ! from print statements\ 2\. Removed line 19 as it didn't mean anything and 20 as it wasn't assigned\ 3\. Matched types on lines 7 and 10 (Had to do manually in code)\ 4\. Removed 25 - 28 as they aren't useful in our evaluation\ 5\. Replaced 22 with Rock and 24 with Tommy Final Results: \ Lyrics > Rocknroll is right\ > Silence is wrong\ > A guitar is a six-string\ > Tommy's been down\ > Music is a billboard-burning razzmatazz!\ > Listen to the music\ > If the music is a guitar\ > Say "Keep on rocking!"\ > Listen to the rhythm\ > If the rhythm without Music is nothing\ > Tommy is rockin guitar\ > Shout Tommy\ > Music is amazing sensation\ > Jamming is awesome presence\ > Scream Music\ > Scream Jamming\ > Tommy is playing rock\ > Scream Tommy\ > Rock is electric heaven\ > Scream Rock\ > Tommy is jukebox god\ > Say Tommy Final Code ```python Rocknroll = True Silence = False a_guitar = 10 Tommy = 44 Music = 170 the_music = input() if int(the_music) == a_guitar: print("Keep on rocking!") the_rhythm = input() if int(the_rhythm) - Music == 0: Tommy = 66 print(Tommy) Music = 79 Jamming = 78 print(Music) print(Jamming) Tommy = 74 print(Tommy) Rock = 86 print(Rock) Tommy = 73 print(Tommy) ``` Output with input being 10 and 170 ```python 10 Keep on rocking! 170 66 79 78 74 86 73 ``` **Flag: picoCTF{BONJVI}** --- # Agent Instructions This documentation is published with GitBook. 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