SMTP Server illegal access failure

2012-02-25 SMTP Server illegal access failure

I took a look in the logs of my ad-hoc SMTP server (running on the main domain) sorescu.eu and I noticed a series of denied authentications.

I did not understand what happened, but I saw the user and the password list encoded in Base64. After I collected all the encoded values, I was curious which credentials were tested. I shall present below the application that I wrote to help me in decoding them, and, the list of passwords used to log in.

Java Base64 decoder code:

Worthy saying, before listing the password list:

the client presented itself as GOD-E49531CFA2A (really?!?);
the client was a bot that was simply dumping plain text to port 25, as it continued sending the mail spam, without even looking that the access was denied;
my SMTP server and relay are the product of one white-night, but this test is a first realistic test of my server;
many more things remain to be implemented in server, including white and black lists, including changing the password with a strong one;

The password series is attached.

Base64Decoder.java

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import javax.xml.bind.DatatypeConverter;

public class Base64 {
	public static void main(String[] args) throws IOException {
		BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
		for (String line = reader.readLine(); line.length() > 0; line = reader.readLine()) {
			String result = new String(DatatypeConverter.parseBase64Binary(line));
			System.out.println(result);
		}
	}
}

passwords.txt

oracle
oracle!@#$
oracle123
oracle1234
master
master!@#$
master123
master1234
server
server!@#$
server123
server1234
sybase
sybase!@#$
sybase123
sybase1234
root
root!@#$
root123
root1234
web
webmaster
webmaster!@#$
webmaster123
webmaster1234
web!@#$
web123
web1234
test
test!@#$
test123
test1234
user
user!@#$
user123
user1234
!@#$
!@#$%
!@#$%^
!@#$%^&
!@#$%^&*
1
111
123
1234
123456
654321
backup
backup!@#$
backup123
backup1234
admin
admin!@#$
admin123
admin1234
asdf
asdfgh
data
data!@#$
data123
data1234