Binary RE

In Plain Text

We got a file called “challenge”. By using strings challenge command, we can see the flag.

Local Picture



Local Picture

When connecting to, we can see as follows:

Local Picture

If we type anything in the box and press “START ONE NOW”, we will connect to, and seems like it is other’s todolist, by changing the number in the URL such as, we can more todolist.

I used OWASP ZAP fuzzer to look for string matching flag or MCA in the content of the website from number 0 to 1000, and got MCA{al3x4_5et_a_r3minder} in the website

Grab Bag


In this challenge, we are given the following picture.

Local Picture

By using Stegsolve, we can get the flag MCA{g1jVx4a2zcpoZx2q}.

Local Picture


Clean Room

When we ssh to ctf@, the commands we can use are restricted. By commanding echo $SHELL, it shows that we are using the restricted bash - rbash.

I used ssh ctf@ -t bash to make myself log in and got bash, and finally got the flag MCA{ieHaisoh4eif2ae} in a directory called root.