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STANDCON 2021

Writeup for STANDCON 2021

STANDCON 2021 Writeup

Forensics

Ancient Computing

Points: 1000

Challenge File:

BOOK1.WK1

Read/Convert old Lotus WK1 and WK4 files

Gnumeric

kali@kali:~/Desktop/STANDCON$ sudo apt-get install gnumeric

Flag:

# Round 0.2524130133933795 up to 14th decimal place

STC{0.25241301339338}

Astronaut Document

Points: 1000

Challenge File:

astronaut_document.txt

  • base64 String

    $e = '';
$e .= 'R';
$e .= 'X';
$e .= 'J';
$e .= 'y';
$e .= 'b';
$e .= '3';
$e .= 'I';
$e .= 'g';
$e .= 'Y';
$e .= 'X';
$e .= 'Q';
$e .= 'g';
$e .= 'b';
$e .= '2';
$e .= 'J';
$e .= 'q';
$e .= 'Z';
$e .= 'W';
$e .= 'N';
$e .= '0';
$e .= 'c';
$e .= 'y';
$e .= 'A';
$e .= '3';
$e .= 'L';
$e .= 'D';
$e .= 'k';
$e .= 's';
$e .= 'M';
$e .= 'T';
$e .= 'A';
$e .= 'g';
$e .= 'Y';
$e .= 'W';
$e .= '5';
$e .= 'k';
$e .= 'I';
$e .= 'D';
$e .= 'E';
$e .= 'z';
$e .= 'I';
$e .= 'G';
$e .= 'l';
$e .= 'u';
$e .= 'I';
$e .= 'H';
$e .= 'R';
$e .= 'o';
$e .= 'Z';
$e .= 'S';
$e .= 'B';
$e .= 'k';
$e .= 'b';
$e .= '2';
$e .= 'N';
$e .= '1';
$e .= 'b';
$e .= 'W';
$e .= 'V';
$e .= 'u';
$e .= 'd';
$e .= 'A';
$e .= 'p';
$e .= 'Q';
$e .= 'b';
$e .= 'G';
$e .= 'V';
$e .= 'h';
$e .= 'c';
$e .= '2';
$e .= 'U';
$e .= 'g';
$e .= 'Z';
$e .= 'm';
$e .= 'l';
$e .= '4';
$e .= 'I';
$e .= 'H';
$e .= 'R';
$e .= 'o';
$e .= 'Z';
$e .= 'S';
$e .= 'B';
$e .= 'l';
$e .= 'c';
$e .= 'n';
$e .= 'J';
$e .= 'v';
$e .= 'c';
$e .= 'n';
$e .= 'M';
$e .= 's';
$e .= 'I';
$e .= 'H';
$e .= 'R';
$e .= 'o';
$e .= 'Z';
$e .= 'S';
$e .= 'B';
$e .= 'm';
$e .= 'b';
$e .= '2';
$e .= 'x';
$e .= 's';
$e .= 'b';
$e .= '3';
$e .= 'd';
$e .= 'p';
$e .= 'b';
$e .= 'm';
$e .= 'c';
$e .= 'g';
$e .= 'b';
$e .= 'G';
$e .= 'l';
$e .= 'u';
$e .= 'a';
$e .= 'y';
$e .= 'B';
$e .= 't';
$e .= 'Y';
$e .= 'X';
$e .= 'k';
$e .= 'g';
$e .= 'a';
$e .= 'G';
$e .= 'V';
$e .= 's';
$e .= 'c';
$e .= 'D';
$e .= 'o';
$e .= 'K';
$e .= 'a';
$e .= 'H';
$e .= 'R';
$e .= '0';
$e .= 'c';
$e .= 'H';
$e .= 'M';
$e .= '6';
$e .= 'L';
$e .= 'y';
$e .= '9';
$e .= 'n';
$e .= 'Z';
$e .= 'W';
$e .= '5';
$e .= 'k';
$e .= 'a';
$e .= 'W';
$e .= 'd';
$e .= 'u';
$e .= 'b';
$e .= '3';
$e .= 'V';
$e .= '4';
$e .= 'L';
$e .= 'm';
$e .= 'N';
$e .= 'v';
$e .= 'b';
$e .= 'S';
$e .= '9';
$e .= 'i';
$e .= 'b';
$e .= 'G';
$e .= '9';
$e .= 'n';
$e .= 'L';
$e .= 'z';
$e .= 'I';
$e .= 'w';
$e .= 'M';
$e .= 'T';
$e .= 'Y';
$e .= 'v';
$e .= 'M';
$e .= 'T';
$e .= 'A';
$e .= 'v';
$e .= 'M';
$e .= 'D';
$e .= 'Q';
$e .= 'v';
$e .= 'c';
$e .= 'G';
$e .= 'R';
$e .= 'm';
$e .= 'L';
$e .= 'W';
$e .= 'J';
$e .= 'h';
$e .= 'c';
$e .= '2';
$e .= 'l';
$e .= 'j';
$e .= 'c';
$e .= 'y';
$e .= '5';
$e .= 'o';
$e .= 'd';
$e .= 'G';
$e .= '1';
$e .= 's';
print(decode_base64($e));

RXJyb3IgYXQgb2JqZWN0cyA3LDksMTAgYW5kIDEzIGluIHRoZSBkb2N1bWVudApQbGVhc2UgZml4IHRoZSBlcnJvcnMsIHRoZSBmb2xsb3dpbmcgbGluayBtYXkgaGVscDoKaHR0cHM6Ly9nZW5kaWdub3V4LmNvbS9ibG9nLzIwMTYvMTAvMDQvcGRmLWJhc2ljcy5odG1s

Introduction to PDF syntax

astronaut_document.pdf

Crypto

Space Noise

Points: 1000

Challenge File:

space_noise.pcap

Notice how SYN and PSH act as delimiters while we have URG and RST acting as binary 1 and 0

Notice how SYN and PSH act as delimiters while we have URG and RST acting as binary 1 and 0

import json

MORSE_CODE_DICT = { 'A':'.-', 'B':'-...',
                    'C':'-.-.', 'D':'-..', 'E':'.',
                    'F':'..-.', 'G':'--.', 'H':'....',
                    'I':'..', 'J':'.---', 'K':'-.-',
                    'L':'.-..', 'M':'--', 'N':'-.',
                    'O':'---', 'P':'.--.', 'Q':'--.-',
                    'R':'.-.', 'S':'...', 'T':'-',
                    'U':'..-', 'V':'...-', 'W':'.--',
                    'X':'-..-', 'Y':'-.--', 'Z':'--..',
                    '1':'.----', '2':'..---', '3':'...--',
                    '4':'....-', '5':'.....', '6':'-....',
                    '7':'--...', '8':'---..', '9':'----.',
                    '0':'-----', ', ':'--..--', '.':'.-.-.-',
                    '?':'..--..', '/':'-..-.', '-':'-....-',
                    '(':'-.--.', ')':'-.--.-'}

data = json.loads(open('space_noise.json').read())
result = ''

curr = ''
for packet in data:
    flags = packet['_source']['layers']['tcp']['tcp.flags_tree']

    if flags['tcp.flags.reset'] == '1':
        curr += 'R'

    elif flags['tcp.flags.push'] == '1':

        if not curr:
            continue

        morse_code = ''
        for char in curr:
            if char == 'R':
                morse_code += '.'
            else:
                morse_code += '-'

        print(curr, morse_code)

        for key in MORSE_CODE_DICT:
            if MORSE_CODE_DICT[key] == morse_code:
                result += key

        curr = ''

    elif flags['tcp.flags.urg'] == '1':
        curr += 'U'

print(result)

python3 solve.py
...
5354437B492062656C6965766520746861742074686973204E6174696F6E2073686F756C6420636F6D6D697420697473656C6620746F20616368696576696E672074686520676F616C2C206265666F7265207468697320646563616465206973206F75742C206F66206C616E64696E672061206D616E206F6E20746865204D6F6F6E20616E642072657475726E696E672068696D20736166656C7920746F2045617274682E7D


STC{I believe that this Nation should commit itself to achieving the goal, before this decade is out, of landing a man on the Moon and returning him safely to Earth.}

Substitution Extreme

Points: 1000

Challenge File:

transmission.txt

--- BEGIN INTERCEPTED TRANSMISSION ---

EZWUFROD HOPVGWUEG GIGRGB HZFUGB PZVGEG WURGU AGPV MZERZMGD IO HZRGMGP HZJZPGPQUPV JZRGAU IO GHOG MZPVVGEG. HOPVGWUEG MZEWOHGB IGEO JGRGAHOG IZPVGP HZRGM QXBXE IO UMGEG, IGP DZWURGUGP EOGU OPIXPZHOG IZPVGP HZRGM HOPVGWUEG IO HZRGMGP. HOPVGWUEG GIGRGB HGRGB HGMU WUHGM DZKGPVGP MZEUPVVUR, IGP IODZPGRO HZFGVGO HZFUGB FGPIGEGAG VRXFGR JZMEXWXROMGP AGPV JZJGOPDGP WZEGPGP WZPMOPV IGRGJ WZEIGVGPVGP IGP DZKGPVGP GPMGEGFGPVHG. WZRGFUBGP HOPVGWUEG JZEUWGDGP HGRGB HZFUGB IGEOWGIG ROJG WZRGFUBGP MZEHOFUD IUPOG.

HUJFZE: KODOWZIOG

--- END INTERCEPTED TRANSMISSION ---


REPUBLIK SINGAPURA ADALAH SEBUAH NEGARA PULAU YANG TERLETAK DI SELATAN SEMENANJUNG MELAYU DI ASIA TENGGARA. SINGAPURA TERPISAH DARI MALAYSIA DENGAN SELAT JOHOR DI UTARA, DAN KEPULAUAN RIAU INDONESIA DENGAN SELAT SINGAPURA DI SELATAN. SINGAPURA ADALAH SALAH SATU PUSAT KEWANGAN TERUNGGUL, DAN DIKENALI SEBAGAI SEBUAH BANDARAYA GLOBAL METROPOLITAN YANG MEMAINKAN PERANAN PENTING DALAM PERDAGANGAN DAN KEWANGAN ANTARABANGSA. PELABUHAN SINGAPURA MERUPAKAN SALAH SEBUAH DARIPADA LIMA PELABUHAN TERSIBUK DUNIA. SUMBER: WIKIPEDIA

STC{REPUBLIK SINGAPURA ADALAH SEBUAH NEGARA PULAU}

Pwn

Rocket Science

Points: 1000

Challenge Files:

requirements.txt

rocket_science.py

Misc

Random Encode

Points: 1000

Challenge File:

flag.txt

nc 20.198.209.142 55051
Welcome to my random encryption server! please enter your plaintext..
STC{testing}
2 0 1 S B \ @ ^ R T { % C 8 T ^ { t   Q e i y s K e a f 4 t o R \ w D i B ^ G " b n Y   N g S Z m ( }

STC{hello}
2 0 1 S % } B \ @ T ^ R C { % 8 { h T ^ e   Q l i y K e a l f 4 o R \ o w D B ^ G } 

8 9 2 % S B - T j # c > e C _ w ^ ` o { " r % c x 4 R a k } ) n 7 D v d k 0 z m ) . " ? a 1 2 y ? _ ~ i p w # l z r r / w b [ 3 b + _ : Z d 2 E Z _ i $ k E > c o + R j 5 C a X H b V z ] [ l e - M R x }

STC{ " r % c x 4 R a k } ) n 7 D v d k 0 z m ) . " ? a 1 2 y ? _ ~ i p w # l z r r / w b [ 3 b + _ : Z d 2 E Z _ i $ k E > c o + R j 5 C a X H b V z ] [ l e - M R x }

Mend the lift to Space

Points: 1000

Challenge File:

liftoff.pass

Mendeleeve created the Periodic Table

Periodic Table Cipher - Chemical Element Number Online Translator

52 53 36 92 36 73 20 78 18 84 53 83 90 64 77 21 79 40 86 34 72 20 64 17 71 64 53 73 38 64 86 79 18 87 20 83 84 38 94

Atomic.csv

STC{Ch3m1sTry_l4nGuAg3_0f_ThE_un1v3rsE}

Transmission

Points: 1000

Challenge File:

# Extract MPEG from Space.jpg using dd command

/static/content/standcon-2021/extract.mp4

ffmpeg -i extract.mp4 frames/out-%01d.jpg

jpg.zip

solve.py

solve_v2.py