Base64

We are given the following string:

bmMze3dvd19iYXNlNjRfZXJfdmlsZHRfbm9rfQ==

We can decode the base64 in a shell with the base64 command:

$ echo "bmMze3dvd19iYXNlNjRfZXJfdmlsZHRfbm9rfQ==" | base64 -d
nc3{wow_base64_er_vildt_nok}

We have now got the flag

Regler

We are asked to read the ctf rules, when we do so we find the flag at the bottom:

nc3{Tak_fordi_du_kiggede_paa_reglerne}

Strings

We are given a file called strings that is 16 KB and a ELF executable:

$ ls -lh
-rw-r--r-- 1 osiriz osiriz  16K  1 dec 19:29  strings

$ file strings
strings: ELF 64-bit LSB pie executable, x86-64, version 1 (SYSV),
dynamically linked, interpreter /lib64/ld-linux-x86-64.so.2,
BuildID[sha1]=0b230c84c7a83f5633a1087dfd516d9a2f815ea8,
for GNU/Linux 3.2.0, not stripped

Running the file doesn’t give us the flag though:

$ ./strings
Flaget findes ikke ved at eksekvere mig!
Men flaget er da 28 tegn langt.

But if we run strings command on the file we are able to find the flag:

$ strings ./strings | grep "nc3{"
nc3{strings finder flaget!}