Port Scanner 7

Sendmail is certainly the buggiest daemon on earth; it has the highest number of known exploits amongst all the daemons. So this probably should get us through. Let us telnet to Port 25 and find out whether an exploitable version of Sendmail is running.




C:\windows> telnet xxx.bol.net.in 25



220 xxx.bol.net.in ESMTP Sendmail 8.9.1 (1.1.20.3/27Jun00-0346PM) Thu, 29 Jun 2000 14:18:12 0530 (IST)



When you telnet to Port 25, then the first thing that you come across would be a something like the above welcome daemon banner. A daemon banner is a Hacker’s best friend. It reveals important information about the host, which proves to be invaluable in breaking into it. It basically tells you which daemon or service is running on that port and also the version of that particular service. Like for example, in this case, the Sendmail daemon banner tells us that ESMTP Sendmail 8.9.1 is running and it also gives us other information about the host at which this service is running.



Anyway, getting back to the topic, this banner reveals a big vulnerability existing in the host computer. It tells us that xxx.bol.net.in is running an old, vulnerable version of Sendmail. The latest version is Sendmail 8.9.4 (correct me if I am wrong.), so this particular version of Sendmail wouldn’t be without any bugs.



So then what you do is visit PacketStorm or search at your favorite Hacking stuff related search engine for a C program which demonstrates how to exploit version 8.9.4 of Sendmail. Now, all this might sound a bit too simple, well it certainly isn’t, read on for more info.



Now, there are a couple of things that you need to keep in mind while getting this done. Say, you have found out that the victim runs Sendmail 8.9.4, now you cannot simply break in by running any exploit for this version. By that what, I mean to say is that, an exploit, which is coded to be executed on a Linux platform, will not work if you try to compile and run it on a Windows platform. So basically before you execute the ‘kewl’ exploit program that you downloaded, you should find out which platform it is meant for and if you are not running that platform, then you will need to get your gray cells working.

Jai Shree Raam