The archaeological team at ångstromCTF has uncovered an archive from over 100 years ago! Can you read the contents?
Access the file at /problems/2021/archaic/archive.tar.gz on the shell server.
Our flag is sitting in a tarball on the shell server. Let's try to extract it:
team8317@actf:/problems/2021/archaic$ tar zxvf archive.tar.gz
flag.txt
tar: flag.txt: Cannot open: Operation not permitted
tar: Exiting with failure status due to previous errors
It looks like we don't have write access here. Let's try to extract to our home folder instead:
team8317@actf:/problems/2021/archaic$ tar zxvf archive.tar.gz -C /home/team8317/
flag.txt
tar: flag.txt: implausibly old time stamp 1921-04-01 22:45:12
It looks like that worked! Now to open up the flag:
team8317@actf:/problems/2021/archaic$ cat ~/flag.txt
cat: /home/team8317/flag.txt: Permission denied
Alright, we can't open it. But why?
team8317@actf:~$ ls -lah
total 68K
drwx------ 3 team8317 team8317 4.0K Apr 3 12:25 .
drwx--x--x 1180 root root 36K Apr 3 12:24 ..
-rw------- 1 team8317 team8317 348 Apr 3 00:14 .bash_history
-rw-r--r-- 1 team8317 team8317 220 Feb 25 2020 .bash_logout
-rw-r--r-- 1 team8317 team8317 3.7K Feb 25 2020 .bashrc
drwx------ 2 team8317 team8317 4.0K Apr 2 22:48 .cache
-rw-r--r-- 1 team8317 team8317 807 Feb 25 2020 .profile
---------- 1 team8317 team8317 37 Apr 1 1921 flag.txt
It looks like we don't have read access. Let's fix that:
team8317@actf:~$ chmod 777 flag.txt
team8317@actf:~$ cat flag.txt
actf{thou_hast_uncovered_ye_ol_fleg}
And now we can read our flag: actf{thou_hast_uncovered_ye_ol_fleg}.