Writeup for the wargame Narnia on OverTheWire.
As the web states, all you need is under /narnia. There you will find a bunch
of dangerous binaries (with active SUID) along with the source code:
narnia0@narnia:~$ ls -al /narnia/
total 116
drwxr-xr-x 2 root root 4096 Aug 26 2019 .
drwxr-xr-x 27 root root 4096 Aug 26 2019 ..
-r-sr-x--- 1 narnia1 narnia0 7456 Aug 26 2019 narnia0
-r--r----- 1 narnia0 narnia0 1229 Aug 26 2019 narnia0.c
-r-sr-x--- 1 narnia2 narnia1 7296 Aug 26 2019 narnia1
-r--r----- 1 narnia1 narnia1 1021 Aug 26 2019 narnia1.c
-r-sr-x--- 1 narnia3 narnia2 5048 Aug 26 2019 narnia2
-r--r----- 1 narnia2 narnia2 1022 Aug 26 2019 narnia2.c
-r-sr-x--- 1 narnia4 narnia3 5676 Aug 26 2019 narnia3
-r--r----- 1 narnia3 narnia3 1699 Aug 26 2019 narnia3.c
-r-sr-x--- 1 narnia5 narnia4 5224 Aug 26 2019 narnia4
-r--r----- 1 narnia4 narnia4 1080 Aug 26 2019 narnia4.c
-r-sr-x--- 1 narnia6 narnia5 5588 Aug 26 2019 narnia5
-r--r----- 1 narnia5 narnia5 1262 Aug 26 2019 narnia5.c
-r-sr-x--- 1 narnia7 narnia6 5948 Aug 26 2019 narnia6
-r--r----- 1 narnia6 narnia6 1602 Aug 26 2019 narnia6.c
-r-sr-x--- 1 narnia8 narnia7 6532 Aug 26 2019 narnia7
-r--r----- 1 narnia7 narnia7 1964 Aug 26 2019 narnia7.c
-r-sr-x--- 1 narnia9 narnia8 5132 Aug 26 2019 narnia8
-r--r----- 1 narnia8 narnia8 1269 Aug 26 2019 narnia8.cSo we are expected to exploit these binaries to gain access to the next levels. I recommend you to download the source code and have it open while you do the challenges, as all of them are about auditing C code.