Heya,

this is probably the same piece of malware that has been discussed on f-d recently. The username/password combination guest and test are hardcoded into a little statically linked binary which is commonly used together with a SYN scanner.

Chances are good these attempts are coming from a compromised box - you may want to look into that if it is in your realms.

If you need more info, I disassembled them both and made a quick analysis, check the f-d archives.

Cheers, J.