Noah’s Compression (200)

programming - Virginia TSA Technosphere CTF

Challenge description:

Let’s see if you can extract a flag from a file without any file extensions

Download file: noahscompression

Solution

We can run the file command to see if the header reveals the file type.

$ file noahscompression
noahscompression: ARC archive data, dynamic LZW

Googling ARC archives revealed they could be extracted using the arc utility, which can be installed with aptitude using sudo apt install arc

While the flag file itself still seems to be compressed, the flag itself is in plaintext.

$ arc x noahscompression
Extracting file: flag
$ cat flag
PK
    ��Rxe�lag.txtUT    ��a��aux
                                ��**************************
PK
    ��Rxe���flag.txtUT��aux
                               ��PKN]

Flag

flag{twoofeachcompression}