file-types

Notes

Challenge: File types

A pdf file names Flag.pdf is given. Using file command on it shows that it is "shell archive text"

Command:

file Flag.pdf

Output:

Flag.pdf: shell archive text

I could not read open the pdf file using any pdf viewer. So copied the file and renamed it with .shar extension. For shell archive text files .shar extension is used. Now opening the .shar file in a text editor shows that it is a shell archive text file. It contains shell code.

Running the .sher file generates a file called flag. Running file command it showed that it is a archive file. Renamed it to flag.ar. Extracted the archive using ar command.

Command:

ar -x flag.ar

Get another file called flag. Running file command on it shows that it is a cpio archive file.So renamed it with cpio extension and extracted the archive using cpio command.

Command:

cpio -idv < flag.cpio

It gives another file called flag. Running file command on it shows that it is a bzip2 compressed data.So renamed it with bz2 extension and extracted the archive using bzip2 command.

Command:

bzip2 -d flag.bz2

It gives another file called flag. Running file command on it shows that it is a gzip compressed data.So renamed it with gz extension and extracted the archive using gzip command.

Command:

gzip -d flag.gz

It gives another file called flag. Running file command on it shows that it is a lzip.So renamed it with lz extension and extracted the archive using lzip command.

Command:

lzip -d flag.lz

It gives another file called flag. Running file command on it shows that it is a LZ4 file.So renamed it with lz4 extension and extracted the archive using lz4 command.

Command:

lz4 flag.lz4

It gives another file called flag. Running file command on it shows that it is a LZMA compressed data, non-streamed, size 255 file.So renamed it with lzma extension and extracted the archive using lzma command.

Command:

lzma -d flag.lzma

It gives another file called flag. Running file command on it shows that it is a lzop compressed data - version 1.040, LZO1X-1, os: Unix file.So renamed it with lzo extension and extracted the archive using lzop command.

Command:

lzop -d flag.lzo

It gives another file called flag. Running file command on it shows that it is a lzip.So renamed it with lz extension and extracted the archive using lzip command.

Command:

lzip -d flag.lz

It gives another file called flag. Running file command on it shows that it is a xz.So renamed it with xz extension and extracted the archive using xz command.

Command:

xz -d flag.xz

It gives another file called flag. Running file command on it shows that it is a ASCII text file.This file contains a hax string.Converting the hax to ASCII gives the flag.

Command:

 echo 7069636f4354467b66316c656e406d335f6d406e3170756c407431306e5f6630725f3062326375723137795f33633739633562617d0a | xxd -r -p

The flag:

picoCTF{f1len@m3_m@n1pul@t10n_f0r_0b2cur17y_3c79c5ba}