ekoparty 2011 CTF [Bin] [writeup]

During the last week I have been in the ekoparty security conference, held in Buenos Aires, Argentina. My team (Kcho Team) was pleased to win the competition (after a long-stressed battle). Here is the Bin writeup:



After some scanning with Nmap, we realize that the 10 IP's (10.10.1-10.68) had ports: 3030, 2011 and 5050 open. Moreover, in the port 5050 was running an http daemon. After quick dir-scan, we discover an interesting file in /image/bin in the 10 servers (different for different servers):

C2726=i ?@AC@3=6>@
7=28i `2675_`432672hg6`4c3f5c46cfb45e`
4@56i ab`ahbcdhf`ae`ae

Analyzing this springs to mind "ROT 13", but with no luck. After quick scripting, ROT47

is the answer:

rafael: noproblemo  

flag: 1aefd01cbaefa98e1c4b7d4ce473cd61  

code:   2312934597126126

rafael : noproblemo => SSH Login for that server.
1aefd01cbaefa98e1c4b7d4ce473cd61  => Flag to submit for "Bin" challenge.
2312934597126126 => code to use after login. Code can be used one time on each server. Some codes also show flags after succesful login.


writeup by: localh0t (@mattdch)